what are the end products of photosynthesis used for

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Photosynthesis

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Photosynthesis Definition

Photosynthesis is the biochemical pathway which converts the energy of light into the bonds of glucose molecules. The process of photosynthesis occurs in two steps. In the first step, energy from light is stored in the bonds of adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). These two energy-storing cofactors are then used in the second step of photosynthesis to produce organic molecules by combining carbon molecules derived from carbon dioxide (CO 2 ). The second step of photosynthesis is known as the Calvin Cycle. These organic molecules can then be used by mitochondria to produce ATP, or they can be combined to form glucose, sucrose, and other carbohydrates. The chemical equation for the entire process can be seen below.

Photosynthesis Equation

Above is the overall reaction for photosynthesis. Using the energy from light and the hydrogens and electrons from water, the plant combines the carbons found in carbon dioxide into more complex molecules. While a 3-carbon molecule is the direct result of photosynthesis, glucose is simply two of these molecules combined and is often represented as the direct result of photosynthesis due to glucose being a foundational molecule in many cellular systems. You will also notice that 6 gaseous oxygen molecules are produced, as a by-produce. The plant can use this oxygen in its mitochondria during oxidative phosphorylation . While some of the oxygen is used for this purpose, a large portion is expelled into the atmosphere and allows us to breathe and undergo our own oxidative phosphorylation, on sugar molecules derived from plants. You will also notice that this equation shows water on both sides. That is because 12 water molecules are split during the light reactions, while 6 new molecules are produced during and after the Calvin cycle. While this is the general equation for the entire process, there are many individual reactions which contribute to this pathway.

Stages of Photosynthesis

The light reactions.

The light reactions happen in the thylakoid membranes of the chloroplasts of plant cells. The thylakoids have densely packed protein and enzyme clusters known as photosystems . There are two of these systems, which work in conjunction with each other to remove electrons and hydrogens from water and transfer them to the cofactors ADP and NADP + . These photosystems were named in the order of which they were discovered, which is opposite of how electrons flow through them. As seen in the image below, electrons excited by light energy flow first through photosystem II (PSII), and then through photosystem I (PSI) as they create NADPH. ATP is created by the protein ATP synthase , which uses the build-up of hydrogen atoms to drive the addition of phosphate groups to ADP.

The entire system works as follows. A photosystem is comprised of various proteins that surround and connect a series of pigment molecules . Pigments are molecules that absorb various photons, allowing their electrons to become excited. Chlorophyll a is the main pigment used in these systems, and collects the final energy transfer before releasing an electron. Photosystem II starts this process of electrons by using the light energy to split a water molecule, which releases the hydrogen while siphoning off the electrons. The electrons are then passed through plastoquinone, an enzyme complex that releases more hydrogens into the thylakoid space . The electrons then flow through a cytochrome complex and plastocyanin to reach photosystem I. These three complexes form an electron transport chain , much like the one seen in mitochondria. Photosystem I then uses these electrons to drive the reduction of NADP + to NADPH. The additional ATP made during the light reactions comes from ATP synthase, which uses the large gradient of hydrogen molecules to drive the formation of ATP.

The Calvin Cycle

With its electron carriers NADPH and ATP all loaded up with electrons, the plant is now ready to create storable energy. This happens during the Calvin Cycle , which is very similar to the citric acid cycle seen in mitochondria. However, the citric acid cycle creates ATP other electron carriers from 3-carbon molecules, while the Calvin cycle produces these products with the use of NADPH and ATP. The cycle has 3 phases, as seen in the graphic below.

During the first phase, a carbon is added to a 5-carbon sugar, creating an unstable 6-carbon sugar. In phase two, this sugar is reduced into two stable 3-carbon sugar molecules. Some of these molecules can be used in other metabolic pathways, and are exported. The rest remain to continue cycling through the Calvin cycle. During the third phase, the five-carbon sugar is regenerated to start the process over again. The Calvin cycle occurs in the stroma of a chloroplast. While not considered part of the Calvin cycle, these products can be used to create a variety of sugars and structural molecules.

Products of Photosynthesis

The direct products of the light reactions and the Calvin cycle are 3-phosphoglycerate and G3P, two different forms of a 3-carbon sugar molecule. Two of these molecules combined equals one glucose molecule, the product seen in the photosynthesis equation. While this is the main food source for plants and animals, these 3-carbon skeletons can be combined into many different forms. A structural form worth note is cellulose , and extremely strong fibrous material made essentially of strings of glucose. Besides sugars and sugar-based molecules, oxygen is the other main product of photosynthesis. Oxygen created from photosynthesis fuels every respiring organism on the planet.

Lodish, H., Berk, A., Kaiser, C. A., Krieger, M., Scott, M. P., Bretscher, A., . . . Matsudaira, P. (2008). Molecular Cell Biology 6th. ed . New York: W.H. Freeman and Company. Nelson, D. L., & Cox, M. M. (2008). Principles of Biochemistry . New York: W.H. Freeman and Company.

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Photosynthesis: Reactants and Products

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Photosynthesis

1. Photosynthesis is the process plants use to make their own food.

Like all living things, plants need energy to carry out the processes that keep them alive. They get this energy from food. Humans and most other animals are heterotrophs, meaning we have to consume other organisms—plants, other animals, or some combination of the two—for food. However, plants are autotrophs, meaning they create their own food.

Plants use sunlight to convert water and carbon dioxide into glucose and oxygen in a process called photosynthesis . In biology, this information is often expressed using a chemical equation .

Chemical equations typically show the molecules that enter the reaction (the reactants ) to the left and the molecules that result from the reaction (the products ) to the right, separated by an arrow that indicates a reaction taking place.

[Reactants] → [Products]

You can think of the reactants as the ingredients for preparing a meal and the products as the different dishes in that meal.

With that in mind, let’s take a look at the chemical equation for photosynthesis:

Sunlight + 6 CO 2 + 6 H 2 O → C 6 H 12 O 6 + 6 O 2 CO 2 = carbon dioxide H 2 O = water C 6 H 12 O 6 = glucose O 2 = oxygen * Sometimes, you’ll see sunlight, or a symbol indicating the sun, over the arrow in the equation.

Therefore, to produce one molecule of glucose (and 6 molecules of oxygen gas), a plant needs 6 molecules of carbon dioxide and 6 molecules of water.

2. The reactants of photosynthesis are carbon dioxide and water.

We’ve established that plants need carbon dioxide (CO 2 ) and water (H 2 O) to produce their food, but where do these reactants come from and how do they get where they need to go inside the plant?

Plants take in carbon dioxide from the air through small openings in their leaves called stomata. Some plants (most monocots) have stomata on both sides of their leaves, and others (dicots and a few monocots) only have stomata on the underside, or lower epidermis.

Plants get water from the soil surrounding their roots, and water gets to the leaves by traveling through the xylem, part of the plant’s vascular system. In leaves, the xylem and phloem are contained in the vascular bundle.

Once inside the leaf, the carbon dioxide and water molecules move into the cells of the mesophyll, the layer of ground tissue between the upper and lower epidermis. Within these cells, organelles called chloroplasts use the carbon dioxide and water to carry out photosynthesis.

3. Light energy from the sun initiates photosynthesis in the chloroplasts of plant cells.

Plant cells have special organelles called chloroplasts, which serve as the sites for the reactions that make up photosynthesis. Their thylakoid membranes contain a pigment called chlorophyll, which absorbs photons (light energy) from the sun, initiating the light-dependent reactions that take place within the thylakoids.

During these reactions, water molecules (H 2 O) are broken down. NADPH and ATP—high energy molecules that power the production of glucose—are produced during the light-dependent reactions, as well. Electrons and hydrogen ions from the water are used to build NADPH. Hydrogen ions also power the conversion of ADP to ATP.

4. The products of photosynthesis are glucose and oxygen.

Did you know that oxygen is actually a waste product of photosynthesis? Although the hydrogen atoms from the water molecules are used in the photosynthesis reactions, the oxygen molecules are released as oxygen gas (O 2 ). (This is good news for organisms like humans and plants that use oxygen to carry out cellular respiration!) Oxygen passes out of the leaves through the stomata.

The light-independent reactions of photosynthesis—also known as the Calvin cycle—use enzymes in the stroma, along with the energy-carrying molecules (ATP and NADPH) from the light-dependent reactions, to break down carbon dioxide molecules (CO 2 ) into a form that is used to build glucose.The mitochondria in the plant’s cells use cellular respiration to break glucose down into a usable form of energy (ATP), which fuels all the plant’s activities.

After the light-independent reactions, glucose is often made into larger sugars like sucrose or carbohydrates like starch or cellulose. Sugars leave the leaf through the phloem and can travel to the roots for storage or to other parts of the plant, where they’re used as energy to fuel the plant’s activities.

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What Are the Products of Photosynthesis?

Photosynthesis is a set of chemical reactions that plants and other organisms use to make chemical energy in the form of sugar. Like any chemical reaction, photosynthesis has reactants and products . Overall, the reactants of photosynthesis are carbon dioxide and water, while the products of photosynthesis are oxygen and glucose (a sugar).

Here’s a closer look at the products of photosynthesis and the balanced equation for the reaction.

The reactants for photosynthesis are carbon dioxide and water, while the products are the sugar glucose and oxygen.

Balanced Chemical Equation for Photosynthesis

Photosynthesis actually involves many chemical reactions, but the net balanced equation is that six moles of carbon dioxide react with six moles of water to produce one mole of glucose and six moles of oxygen. Light from the Sun provides the activation energy for the reaction. Sometimes light is listed in the balanced equation as a reactant, but it’s usually omitted.

6 CO 2  + 6 H 2 O → C 6 H 12 O 6  + 6 O 2

Carbon Dioxide + Water + Light → Glucose + Oxygen

Closer Look at the Products of Photosynthesis

Photosynthesis occurs in a series of steps that are classified as light-dependent reactions and light-independent reactions. Adding up the reactants and products of these reactions gives the overall equation for photosynthesis, but it’s good to know the inputs and outputs for each stage.

Light-Dependent Reactions

The light-dependent reactions or light reactions absorb certain wavelengths of light to make adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). The light reactions occur in the chloroplast thylakoid membrane. The overall balanced equation for the light-dependent reactions is:

2 H 2 O + 2 NADP +  + 3 ADP + 3 P i  + light → 2 NADPH + 2 H +  + 3 ATP + O 2

Light-Independent Reactions

While the light reactions use water, the light-independent reactions use carbon dioxide. The light-independent reactions are also called the dark reactions. These reactions do not require darkness, but they don’t depend on light to proceed. In plants, algae, and cyanobacteria, the dark reactions are called the Calvin cycle. Bacteria use different reactions, including the reverse Krebs cycle.

The overall balanced equation for the light-independent reactions (Calvin cycle) in plants is:

3 CO 2  + 9 ATP + 6 NADPH + 6 H +  → C 3 H 6 O 3 -phosphate + 9 ADP + 8 P i  + 6 NADP +  + 3 H 2 O

Finally, the three-carbon product from the Calvin cycle becomes glucose during the process of carbon fixation.

Other Products of Photosynthesis

Glucose is the direct product of photosynthesis, but plants turn most of the sugar into other compounds. These are indirect products. Linking glucose units forms starch and cellulose. Cellulose is a structural material. Plants store starch or link it to fructose (another sugar) to form sucrose (table sugar).

What Is Not a Product of Photosynthesis?

On an exam, you may need to identify which chemical is not a product of photosynthesis. For the overall process, choose any answer except “glucose” or “oxygen.” It’s good to know the overall reactants and products of the light reactions and dark reactions, in case you’re asked about them. The products of the light reactions are ATP , NADPH, protons, and oxygen. The products of the dark reactions are C 3 H 6 O 3 -phosphate, ADP, inorganic phosphate, NADP + , and water.

Where Does Photosynthesis Occur?

In addition to knowing the reactants and products of photosynthesis, you may need to know where photosynthesis occurs in different organisms.

• In plants, photosynthesis occurs in organelles called chloroplasts. Photosynthetic protists also contain chloroplasts. Leaves contain the highest concentration of chloroplasts in plants. Plants obtain carbon dioxide via diffusion through leaf stomata. Water comes from the roots and travels to the leaves via the xylem . Chlorophyll in chloroplasts absorbs solar energy. Oxygen from photosynthesis exits the plant via leaf stomata.
• Photosynthesis occurs in photosynthetic bacteria in the plasma membrane. Chlorophyll or related pigments are embedded in this membrane.
• Bidlack, J.E.; Stern, K.R.; Jansky, S. (2003).  Introductory Plant Biology . New York: McGraw-Hill. ISBN 978-0-07-290941-8.
• Blankenship, R.E. (2014).  Molecular Mechanisms of Photosynthesis  (2nd ed.). John Wiley & Sons. ISBN 978-1-4051-8975-0.
• Reece J.B., et al. (2013).  Campbell Biology . Benjamin Cummings. ISBN 978-0-321-77565-8.

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Photosynthetic Cells

Cells get nutrients from their environment, but where do those nutrients come from? Virtually all organic material on Earth has been produced by cells that convert energy from the Sun into energy-containing macromolecules. This process, called photosynthesis, is essential to the global carbon cycle and organisms that conduct photosynthesis represent the lowest level in most food chains (Figure 1).

What Is Photosynthesis? Why Is it Important?

Most living things depend on photosynthetic cells to manufacture the complex organic molecules they require as a source of energy. Photosynthetic cells are quite diverse and include cells found in green plants, phytoplankton, and cyanobacteria. During the process of photosynthesis, cells use carbon dioxide and energy from the Sun to make sugar molecules and oxygen. These sugar molecules are the basis for more complex molecules made by the photosynthetic cell, such as glucose. Then, via respiration processes, cells use oxygen and glucose to synthesize energy-rich carrier molecules, such as ATP, and carbon dioxide is produced as a waste product. Therefore, the synthesis of glucose and its breakdown by cells are opposing processes.

However, photosynthesis doesn't just drive the carbon cycle — it also creates the oxygen necessary for respiring organisms. Interestingly, although green plants contribute much of the oxygen in the air we breathe, phytoplankton and cyanobacteria in the world's oceans are thought to produce between one-third and one-half of atmospheric oxygen on Earth.

What Cells and Organelles Are Involved in Photosynthesis?

Chlorophyll A is the major pigment used in photosynthesis, but there are several types of chlorophyll and numerous other pigments that respond to light, including red, brown, and blue pigments. These other pigments may help channel light energy to chlorophyll A or protect the cell from photo-damage. For example, the photosynthetic protists called dinoflagellates, which are responsible for the "red tides" that often prompt warnings against eating shellfish, contain a variety of light-sensitive pigments, including both chlorophyll and the red pigments responsible for their dramatic coloration.

What Are the Steps of Photosynthesis?

Photosynthesis consists of both light-dependent reactions and light-independent reactions . In plants, the so-called "light" reactions occur within the chloroplast thylakoids, where the aforementioned chlorophyll pigments reside. When light energy reaches the pigment molecules, it energizes the electrons within them, and these electrons are shunted to an electron transport chain in the thylakoid membrane. Every step in the electron transport chain then brings each electron to a lower energy state and harnesses its energy by producing ATP and NADPH. Meanwhile, each chlorophyll molecule replaces its lost electron with an electron from water; this process essentially splits water molecules to produce oxygen (Figure 5).

Once the light reactions have occurred, the light-independent or "dark" reactions take place in the chloroplast stroma. During this process, also known as carbon fixation, energy from the ATP and NADPH molecules generated by the light reactions drives a chemical pathway that uses the carbon in carbon dioxide (from the atmosphere) to build a three-carbon sugar called glyceraldehyde-3-phosphate (G3P). Cells then use G3P to build a wide variety of other sugars (such as glucose) and organic molecules. Many of these interconversions occur outside the chloroplast, following the transport of G3P from the stroma. The products of these reactions are then transported to other parts of the cell, including the mitochondria, where they are broken down to make more energy carrier molecules to satisfy the metabolic demands of the cell. In plants, some sugar molecules are stored as sucrose or starch.

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Basic products of photosynthesis

Evolution of the process, light intensity and temperature.

• Carbon dioxide
• Internal factors
• Energy efficiency of photosynthesis
• Structural features
• Light absorption and energy transfer
• The pathway of electrons
• Evidence of two light reactions
• Photosystems I and II
• Quantum requirements
• The process of photosynthesis: the conversion of light energy to ATP
• Elucidation of the carbon pathway
• Carboxylation
• Isomerization/condensation/dismutation
• Phosphorylation
• Regulation of the cycle
• Products of carbon reduction
• Photorespiration
• Carbon fixation in C 4 plants
• Carbon fixation via crassulacean acid metabolism (CAM)
• Differences in carbon fixation pathways
• The molecular biology of photosynthesis

• Why is photosynthesis important?
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Little free glucose is produced in plants; instead, glucose units are linked to form starch or are joined with fructose , another sugar , to form sucrose ( see carbohydrate ).

Not only carbohydrates, as was once thought, but also amino acids, proteins, lipids (or fats), pigments , and other organic components of green tissues are synthesized during photosynthesis. Minerals supply the elements (e.g., nitrogen , N; phosphorus , P; sulfur , S) required to form these compounds . Chemical bonds are broken between oxygen (O) and carbon (C), hydrogen (H), nitrogen , and sulfur, and new bonds are formed in products that include gaseous oxygen (O 2 ) and organic compounds. More energy is required to break the bonds between oxygen and other elements (e.g., in water , nitrate, and sulfate) than is released when new bonds form in the products. This difference in bond energy accounts for a large part of the light energy stored as chemical energy in the organic products formed during photosynthesis. Additional energy is stored in making complex molecules from simple ones.

Although life and the quality of the atmosphere today depend on photosynthesis, it is likely that green plants evolved long after the first living cells . When Earth was young, electrical storms and solar radiation probably provided the energy for the synthesis of complex molecules from abundant simpler ones, such as water, ammonia , and methane . The first living cells probably evolved from these complex molecules ( see life: Production of polymers ). For example, the accidental joining (condensation) of the amino acid glycine and the fatty acid acetate may have formed complex organic molecules known as porphyrins . These molecules, in turn, may have evolved further into coloured molecules called pigments —e.g., chlorophylls of green plants, bacteriochlorophyll of photosynthetic bacteria, hemin (the red pigment of blood), and cytochromes , a group of pigment molecules essential in both photosynthesis and cellular respiration .

Primitive coloured cells then had to evolve mechanisms for using the light energy absorbed by their pigments. At first, the energy may have been used immediately to initiate reactions useful to the cell . As the process for utilization of light energy continued to evolve, however, a larger part of the absorbed light energy probably was stored as chemical energy, to be used to maintain life. Green plants, with their ability to use light energy to convert carbon dioxide and water to carbohydrates and oxygen, are the culmination of this evolutionary process.

The first oxygenic (oxygen-producing) cells probably were the blue-green algae (cyanobacteria), which appeared about two billion to three billion years ago. These microscopic organisms are believed to have greatly increased the oxygen content of the atmosphere, making possible the development of aerobic (oxygen-using) organisms. Cyanophytes are prokaryotic cells ; that is, they contain no distinct membrane -enclosed subcellular particles ( organelles ), such as nuclei and chloroplasts . Green plants, by contrast, are composed of eukaryotic cells , in which the photosynthetic apparatus is contained within membrane-bound chloroplasts. The complete genome sequences of cyanobacteria and higher plants provide evidence that the first photosynthetic eukaryotes were likely the red algae that developed when nonphotosynthetic eukaryotic cells engulfed cyanobacteria. Within the host cells, these cyanobacteria evolved into chloroplasts.

There are a number of photosynthetic bacteria that are not oxygenic (e.g., the sulfur bacteria previously discussed). The evolutionary pathway that led to these bacteria diverged from the one that resulted in oxygenic organisms. In addition to the absence of oxygen production, nonoxygenic photosynthesis differs from oxygenic photosynthesis in two other ways: light of longer wavelengths is absorbed and used by pigments called bacteriochlorophylls, and reduced compounds other than water (such as hydrogen sulfide or organic molecules) provide the electrons needed for the reduction of carbon dioxide.

Factors that influence the rate of photosynthesis

The rate of photosynthesis is defined in terms of the rate of oxygen production either per unit mass (or area) of green plant tissues or per unit weight of total chlorophyll . The amount of light, the carbon dioxide supply, temperature , water supply , and the availability of minerals are the most important environmental factors that affect the rate of photosynthesis in land plants. The rate of photosynthesis is also determined by the plant species and its physiological state—e.g., its health , its maturity, and whether it is in flower .

As has been mentioned, the complex mechanism of photosynthesis includes a photochemical, or light-harvesting, stage and an enzymatic, or carbon-assimilating, stage that involves chemical reactions. These stages can be distinguished by studying the rates of photosynthesis at various degrees of light saturation (i.e., intensity) and at different temperatures . Over a range of moderate temperatures and at low to medium light intensities (relative to the normal range of the plant species), the rate of photosynthesis increases as the intensity increases and is relatively independent of temperature. As the light intensity increases to higher levels, however, the rate becomes saturated; light “saturation” is achieved at a specific light intensity, dependent on species and growing conditions. In the light-dependent range before saturation, therefore, the rate of photosynthesis is determined by the rates of photochemical steps. At high light intensities, some of the chemical reactions of the dark stage become rate-limiting. In many land plants, a process called photorespiration occurs, and its influence upon photosynthesis increases with rising temperatures. More specifically, photorespiration competes with photosynthesis and limits further increases in the rate of photosynthesis, especially if the supply of water is limited ( see below Photorespiration ).

5.1 Overview of Photosynthesis

Learning objectives.

• Summarize the process of photosynthesis
• Explain the relevance of photosynthesis to other living things
• Identify the reactants and products of photosynthesis
• Describe the main structures involved in photosynthesis

All living organisms on earth consist of one or more cells. Each cell runs on the chemical energy found mainly in carbohydrate molecules (food), and the majority of these molecules are produced by one process: photosynthesis. Through photosynthesis, certain organisms convert solar energy (sunlight) into chemical energy, which is then used to build carbohydrate molecules. The energy used to hold these molecules together is released when an organism breaks down food. Cells then use this energy to perform work, such as cellular respiration.

The energy that is harnessed from photosynthesis enters the ecosystems of our planet continuously and is transferred from one organism to another. Therefore, directly or indirectly, the process of photosynthesis provides most of the energy required by living things on earth.

Photosynthesis also results in the release of oxygen into the atmosphere. In short, to eat and breathe, humans depend almost entirely on the organisms that carry out photosynthesis.

Link to Learning

Click the following link to learn more about photosynthesis.

Solar Dependence and Food Production

Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” ( auto ) “feeder” ( troph ). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae ( Figure 5.2 ). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs , a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight.

Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” ( hetero ) “feeder” ( troph ), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example ( Figure 5.3 ). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis.

Everyday Connection

Photosynthesis at the grocery store.

Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth. Each aisle contains hundreds, if not thousands, of different products for customers to buy and consume ( Figure 5.4 ).

Although there is a large variety, each item links back to photosynthesis. Meats and dairy products link to photosynthesis because the animals were fed plant-based foods. The breads, cereals, and pastas come largely from grains, which are the seeds of photosynthetic plants. What about desserts and drinks? All of these products contain sugar—the basic carbohydrate molecule produced directly from photosynthesis. The photosynthesis connection applies to every meal and every food a person consumes.

Main Structures and Summary of Photosynthesis

Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants ( Figure 5.5 ). After the process is complete, photosynthesis releases oxygen and produces carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy that living things need to survive.

The complex reactions of photosynthesis can be summarized by the chemical equation shown in Figure 5.6 .

Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex, as in the way that the reaction summarizing cellular respiration represented many individual reactions. Before learning the details of how photoautotrophs turn sunlight into food, it is important to become familiar with the physical structures involved.

In plants, photosynthesis takes place primarily in leaves, which consist of many layers of cells and have differentiated top and bottom sides. The process of photosynthesis occurs not on the surface layers of the leaf, but rather in a middle layer called the mesophyll ( Figure 5.7 ). The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata .

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast . In plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double (inner and outer) membrane. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids . Embedded in the thylakoid membrane are molecules of chlorophyll , a pigment (a molecule that absorbs light) through which the entire process of photosynthesis begins. Chlorophyll is responsible for the green color of plants. The thylakoid membrane encloses an internal space called the thylakoid space. Other types of pigments are also involved in photosynthesis, but chlorophyll is by far the most important. As shown in Figure 5.7 , a stack of thylakoids is called a granum , and the space surrounding the granum is called stroma (not to be confused with stomata, the openings on the leaves).

Visual Connection

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

The Two Parts of Photosynthesis

Photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions , which take place at the thylakoid membrane, chlorophyll absorbs energy from sunlight and then converts it into chemical energy with the use of water. The light-dependent reactions release oxygen from the hydrolysis of water as a byproduct. In the Calvin cycle, which takes place in the stroma, the chemical energy derived from the light-dependent reactions drives both the capture of carbon in carbon dioxide molecules and the subsequent assembly of sugar molecules. The two reactions use carrier molecules to transport the energy from one to the other. The carriers that move energy from the light-dependent reactions to the Calvin cycle reactions can be thought of as “full” because they bring energy. After the energy is released, the “empty” energy carriers return to the light-dependent reactions to obtain more energy. The two-stage, two-location photosynthesis process was discovered by Joan Mary Anderson, whose continuing work over the subsequent decades provided much of our understanding of the process, the membranes, and the chemicals involved.

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What Are the Products of Photosynthesis?

Result of Photosynthesis in Plants

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Photosynthesis is the name given to the set of chemical reactions performed by plants to convert energy from the sun into chemical energy in the form of sugar. Specifically, plants use energy from sunlight to react carbon dioxide and water to produce sugar ( glucose ) and oxygen . Many reactions occur, but the overall chemical reaction for photosynthesis is:

• 6 CO 2 + 6 H 2 O + light → C 6 H 12 O 6 + 6 O 2
• Carbon Dioxide + Water + Light yields Glucose + Oxygen

In a plant, the carbon dioxide enters via leaf stomates by diffusion . Water is absorbed through the roots and is transported to leaves through the xylem. Solar energy is absorbed by chlorophyll in the leaves. The reactions of photosynthesis occur in the chloroplasts of plants. In photosynthetic bacteria, the process takes place where chlorophyll or a related pigment is embedded in the plasma membrane. The oxygen and water produced in photosynthesis exit through the stomata.

Key Takeaways

• In photosynthesis, energy from light is used to convert carbon dioxide and water into glucose and oxygen.
• For 6 carbon dioxide and 6 water molecules, 1 glucose molecule and 6 oxygen molecules are produced.

Actually, plants reserve very little of the glucose for immediate use. Glucose molecules are combined by dehydration synthesis to form cellulose, which is used as a structural material. Dehydration synthesis is also used to convert glucose to starch, which plants use to store energy.

Intermediate Products of Photosynthesis

The overall chemical equation is a summary of a series of chemical reactions. These reactions occur in two stages. The light reactions require light (as you might imagine), while the dark reactions are controlled by enzymes. They don't require darkness to occur -- they simply don't depend on light.

The light reactions absorb light and harness the energy to power electron transfers. Most photosynthetic organisms capture visible light, although there are some that use infrared light. Products of these reactions are adenosine triphosphate ( ATP ) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). In plant cells, the light-dependent reactions occur in the chloroplast thylakoid membrane. The overall reaction for the light-dependent reactions is:

• 2 H 2 O + 2 NADP +  + 3 ADP + 3 P i  + light → 2 NADPH + 2 H +  + 3 ATP + O 2

In the dark stage, ATP and NADPH ultimately reduce carbon dioxide and other molecules. Carbon dioxide from the air is "fixed" into a biologically usable form, glucose. In plants, algae, and cyanobacteria, the dark reactions are termed the Calvin cycle. Bacteria may use different reactions, including a reverse Krebs cycle . The overall reaction for the light-independent reaction of a plant (Calvin cycle) is:

• 3 CO 2  + 9 ATP + 6 NADPH + 6 H +  → C 3 H 6 O 3 -phosphate + 9 ADP + 8 P i  + 6 NADP +  + 3 H 2 O

During carbon fixation, the three-carbon product of the Calvin cycle is converted into the final carbohydrate product.

Factors That Affect the Rate of Photosynthesis

Like any chemical reaction, the availability of the reactants determines the amount of products that can be made. Limiting the availability of carbon dioxide or water slows the production of glucose and oxygen. Also, the rate of the reactions is affected by temperature and the availability of minerals that may be needed in the intermediate reactions.

The overall health of the plant (or other photosynthetic organism) also plays a role. The rate of metabolic reactions is determined in part by the maturity of the organism and whether it's flowering or bearing fruit.

What Is Not a Product of Photosynthesis?

If you're asked about photosynthesis on a test, you may be asked to identify the products of the reaction. That's pretty easy, right? Another form of the question is to ask what is not a product of photosynthesis. Unfortunately, this won't be an open-ended question, which you could easily answer with "iron" or "a car" or "your mom." Usually this is a multiple choice question, listing molecules which are reactants or products of photosynthesis. The answer is any choice except glucose or oxygen. The question may also be phrased to answer what is not a product of the light reactions or the dark reactions. So, it's a good idea to know the overall reactants and products for the photosynthesis general equation, the light reactions, and the dark reactions.

• Bidlack, J.E.; Stern, K.R.; Jansky, S. (2003). Introductory Plant Biology . New York: McGraw-Hill. ISBN 978-0-07-290941-8.
• Blankenship, R.E. (2014). Molecular Mechanisms of Photosynthesis (2nd ed.). John Wiley & Sons. ISBN 978-1-4051-8975-0.
• Reece J.B., et al. (2013). Campbell Biology . Benjamin Cummings. ISBN 978-0-321-77565-8.
• Examples of Chemical Reactions in Everyday Life
• A to Z Chemistry Dictionary
• Phases of the Bacterial Growth Curve
• Photosynthesis Basics - Study Guide
• Photosynthesis Vocabulary Terms and Definitions
• The Photosynthesis Formula: Turning Sunlight into Energy
• Calvin Cycle Steps and Diagram
• 10 Fascinating Photosynthesis Facts
• Chloroplast Function in Photosynthesis
• Chlorophyll Definition and Role in Photosynthesis
• What Is the Primary Function of the Calvin Cycle?
• The Balanced Chemical Equation for Photosynthesis
• All About Photosynthetic Organisms
• Thylakoid Definition and Function
• Simple Chemical Reactions
• An Introduction to Types of Respiration

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show/hide words to know

ATP: adenosine triphosphate. ATP is the energy-carrying molecule of all cells...... more

Cellulose: the structural material found in the cell wall in most plants. Cellulose is used to make many products, including paper and cloth...  more

Electron transport chain: cell process that uses electrons to generate chemical energy...  more

Ion: an atom or molecule that does not have the same number of electrons as it has protons. This gives the atom or molecule a negative or positive charge...  more

Light-dependent reaction: the first part of photosynthesis where (sun)light energy is captured and stored by a plant...  more

Molecule: a chemical structure that has two or more atoms held together by a chemical bond. Water is a molecule of two hydrogen atoms and one oxygen atom (H2O)...  more

Protein: a type of molecule found in the cells of living things, made up of special building blocks called amino acids.

Starch: made by all green plants and used to store energy for later use...  more

Thylakoid: the disk-shaped parts of a plant cell where light-dependent reactions occur...  more

In with One Energy and out with Another

The light-dependent reactions take place in the thylakoid membrane, inside chloroplasts. Since they are light 'dependent' reactions, you can guess that these reactions need light to work. Remember that the purpose of this first part of photosynthesis is to convert sunlight energy into other forms of energy?

The light-dependent reactions of photosynthesis require sunlight. Image by Mell27.

Plants cannot use light energy directly to make sugars. Instead, the plant changes the light energy into a form it can use: chemical energy. Chemical energy is all around us. For example, cars need the chemical energy from gasoline to run. The chemical energy that plants use are stored in ATP and NADPH. ATP and NADPH are two kinds of energy-carrying molecules. These two molecules are not only in plants, as animals use them as well.

A Recipe for Energy

Plants need water to make NADPH. This water is broken apart to release electrons (negatively charged subatomic particles). When water is broken it also creates oxygen, a gas that we all breathe.

The electrons must travel through special proteins stuck in the thylakoid membrane. They go through the first special protein (the photosystem II protein) and down the electron transport chain. Then they pass through a second special protein (photosystem I protein).

Photosystem I and Photosystem II

Wait a second... first electrons go through the second photosystem and second they go through the first? That seems really confusing. Why would they name the photosystems that way?

Water molecules are broken down to release electrons. These electrons then move down a gradient, storing energy in ATP in the process. Image by Jina Lee.

Photosystem I and II don't align with the route electrons take through the transport chain because they weren't discovered in that order. Photosystem I was discovered first. Later, photosystem II was discovered and found to be earlier in the electron transport chain. But it was too late, the name stuck. Electrons first travel through photosystem II and then photosystem I.

The Electron Transport Chain

While at photosystem II and I, the electrons gather energy from sunlight. How do they do that? Chlorophyll, which is present in the photosystems, soaks up light energy. The energized electrons are then used to make NADPH. The electron transport chain is a series of molecules that accept or donate electrons easily. By moving step-by-step through these, electrons are moved in a specific direction across a membrane. The movement of hydrogen ions are coupled with this. This means that when electrons are moved, hydrogen ions move too. ATP is created when hydrogen ions are pumped into the inner space (lumen) of the thylakoid. Hydrogen ions have a positive charge. Like in magnets, the same charges repel, so the hydrogen ions want to get away from each other. They escape the thylakoid through a membrane protein called ATP synthase. By moving through the protein they give it power, like water moving through a dam. When hydrogen ions move through the protein and down the electron transport chain, ATP is created. This is how plants turn to sunlight into chemical energy that they can use.

The Calvin Cycle: Building Life from Thin Air

How does something like air become the wood of a tree? The answer lies in what makes up the air.

How can the air surrounding a tree be turned into tree material? Through a complex set of reactions that use the carbon from the air to make other materials. Image by André Karwath.

The air holds different elements like oxygen, carbon, and nitrogen. These elements make up molecules like carbon dioxide (CO2). Carbon dioxide is made out of one carbon atom and two oxygen atoms. Plants take the carbon atom from carbon dioxide and use it to build sugars. This is done using the Calvin cycle. The Calvin cycle occurs inside chloroplasts, but outside the thylakoids (where ATP was created). The ATP and NADPH from the light-dependent reactions are used in the Calvin cycle. Parts of the Calvin cycle are sometimes called light-independent reactions. But don't let the name fool you... those reactions do require sunlight to work. The protein RuBisCO also helps in the process to change carbon from the air into sugars. RuBisCO works slowly, so plants need a lot of it. In fact, RuBisCO is the most abundant protein in the world! The products of the Calvin cycle are used to make the simple sugar glucose. Glucose is used to build more complex sugars like starch and cellulose. Starch stores energy for the plant and cellulose is the stuff of which plants are made.

Images via Wikimedia Commons. Seedling image by Bff.

Read more about: Snacking on Sunlight

View citation, bibliographic details:.

• Article: Photosynthesis
• Author(s): Heather Kropp, Angela Halasey
• Publisher: Arizona State University School of Life Sciences Ask A Biologist
• Site name: ASU - Ask A Biologist
• Date published: May 25, 2017
• Date accessed: June 12, 2024
• Link: https://askabiologist.asu.edu/photosynthesis

Heather Kropp, Angela Halasey. (2017, May 25). Photosynthesis. ASU - Ask A Biologist. Retrieved June 12, 2024 from https://askabiologist.asu.edu/photosynthesis

Chicago Manual of Style

Heather Kropp, Angela Halasey. "Photosynthesis". ASU - Ask A Biologist. 25 May, 2017. https://askabiologist.asu.edu/photosynthesis

MLA 2017 Style

Heather Kropp, Angela Halasey. "Photosynthesis". ASU - Ask A Biologist. 25 May 2017. ASU - Ask A Biologist, Web. 12 Jun 2024. https://askabiologist.asu.edu/photosynthesis

Plants need chemical energy to grow and survive. But how do they convert energy in sunlight into chemical energy?

Snacking on Sunlight

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6.6: Photosynthesis

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What you’ll learn to do: Identify the basic components and steps of photosynthesis

No matter how complex or advanced a machine, such as the latest cellular phone, the device cannot function without energy. Living things, similar to machines, have many complex components; they too cannot do anything without energy, which is why humans and all other organisms must “eat” in some form or another. That may be common knowledge, but how many people realize that every bite of every meal ingested depends on the process of photosynthesis?

Learning Objectives

• Summarize the process of photosynthesis
• Describe how the wavelength of light affects its energy and color
• Describe the light-dependent reactions that take place during photosynthesis
• Describe the steps and processes in the Calvin Cycle

An Overview of Photosynthesis

All living organisms on earth consist of one or more cells. Each cell runs on the chemical energy found mainly in carbohydrate molecules (food), and the majority of these molecules are produced by one process: photosynthesis. Through photosynthesis, certain organisms convert solar energy (sunlight) into chemical energy, which is then used to build carbohydrate molecules. The energy used to hold these molecules together is released when an organism breaks down food. Cells then use this energy to perform work, such as cellular respiration.

The energy that is harnessed from photosynthesis enters the ecosystems of our planet continuously and is transferred from one organism to another. Therefore, directly or indirectly, the process of photosynthesis provides most of the energy required by living things on earth.

Photosynthesis also results in the release of oxygen into the atmosphere. In short, to eat and breathe, humans depend almost entirely on the organisms that carry out photosynthesis.

Learn more about photosynthesis

Solar Dependence and Food Production

Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” ( auto ) “feeder” ( troph ). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae (Figure 2). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs, a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight.

Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” ( hetero ) “feeder” ( troph ), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example (Figure 3). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis.

Photosynthesis is a multi-step process that requires sunlight, carbon dioxide (which is low in energy), and water as substrates (Figure 4). After the process is complete, it releases oxygen and produces glyceraldehyde-3-phosphate (GA3P), simple carbohydrate molecules (which are high in energy) that can subsequently be converted into glucose, sucrose, or any of dozens of other sugar molecules. These sugar molecules contain energy and the energized carbon that all living things need to survive.

The following is the chemical equation for photosynthesis (Figure 5):

Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex. Before learning the details of how photoautotrophs turn sunlight into food, it is important to become familiar with the structures involved.

In plants, photosynthesis generally takes place in leaves, which consist of several layers of cells. The process of photosynthesis occurs in a middle layer called the mesophyll . The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata (singular: stoma), which also play roles in the regulation of gas exchange and water balance. The stomata are typically located on the underside of the leaf, which helps to minimize water loss. Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes.

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast . For plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double membrane envelope (composed of an outer membrane and an inner membrane). Within the chloroplast are stacked, disc-shaped structures called thylakoids . Embedded in the thylakoid membrane is chlorophyll, a pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain. The thylakoid membrane encloses an internal space called the thylakoid lumen . As shown in Figure 6, a stack of thylakoids is called a granum , and the liquid-filled space surrounding the granum is called stroma or “bed” (not to be confused with stoma or “mouth,” an opening on the leaf epidermis).

Practice Question

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

Levels of carbon dioxide (a necessary photosynthetic substrate) will immediately fall. As a result, the rate of photosynthesis will be inhibited.

The Two Parts of Photosynthesis

Photosynthesis takes place in two sequential stages: the light-dependent reactions and the light independent-reactions. In the light-dependent reactions , energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. In the light-independent reactions , the chemical energy harvested during the light-dependent reactions drive the assembly of sugar molecules from carbon dioxide. Therefore, although the light-independent reactions do not use light as a reactant, they require the products of the light-dependent reactions to function. In addition, several enzymes of the light-independent reactions are activated by light. The light-dependent reactions utilize certain molecules to temporarily store the energy: These are referred to as energy carriers. The energy carriers that move energy from light-dependent reactions to light-independent reactions can be thought of as “full” because they are rich in energy. After the energy is released, the “empty” energy carriers return to the light-dependent reaction to obtain more energy. Figure 7 illustrates the components inside the chloroplast where the light-dependent and light-independent reactions take place.

Click the link to learn more about photosynthesis.

Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth. Each aisle (Figure 8) contains hundreds, if not thousands, of different products for customers to buy and consume.

Although there is a large variety, each item links back to photosynthesis. Meats and dairy link because the animals were fed plant-based foods. The breads, cereals, and pastas come largely from starchy grains, which are the seeds of photosynthesis-dependent plants. What about desserts and drinks? All of these products contain sugar—sucrose is a plant product, a disaccharide, a carbohydrate molecule, which is built directly from photosynthesis. Moreover, many items are less obviously derived from plants: for instance, paper goods are generally plant products, and many plastics (abundant as products and packaging) can be derived from algae or from oil, the fossilized remains of photosynthetic organisms. Virtually every spice and flavoring in the spice aisle was produced by a plant as a leaf, root, bark, flower, fruit, or stem. Ultimately, photosynthesis connects to every meal and every food a person consumes.

The process of photosynthesis transformed life on Earth. By harnessing energy from the sun, photosynthesis evolved to allow living things access to enormous amounts of energy. Because of photosynthesis, living things gained access to sufficient energy that allowed them to build new structures and achieve the biodiversity evident today.

Only certain organisms, called photoautotrophs, can perform photosynthesis; they require the presence of chlorophyll, a specialized pigment that absorbs certain portions of the visible spectrum and can capture energy from sunlight. Photosynthesis uses carbon dioxide and water to assemble carbohydrate molecules and release oxygen as a waste product into the atmosphere. Eukaryotic autotrophs, such as plants and algae, have organelles called chloroplasts in which photosynthesis takes place, and starch accumulates. In prokaryotes, such as cyanobacteria, the process is less localized and occurs within folded membranes, extensions of the plasma membrane, and in the cytoplasm.

Light Energy

How can light be used to make food? It is easy to think of light as something that exists and allows living organisms, such as humans, to see, but light is a form of energy. Like all energy, light can travel, change form, and be harnessed to do work. In the case of photosynthesis, light energy is transformed into chemical energy, which autotrophs use to build carbohydrate molecules. However, autotrophs only use a specific component of sunlight (Figure 9).

What Is Light Energy?

The sun emits an enormous amount of electromagnetic radiation (solar energy). Humans can see only a fraction of this energy, which is referred to as “visible light.” The manner in which solar energy travels can be described and measured as waves. Scientists can determine the amount of energy of a wave by measuring its wavelength, the distance between two consecutive, similar points in a series of waves, such as from crest to crest or trough to trough (Figure 10).

Visible light constitutes only one of many types of electromagnetic radiation emitted from the sun. The electromagnetic spectrum is the range of all possible wavelengths of radiation (Figure 11). Each wavelength corresponds to a different amount of energy carried.

Each type of electromagnetic radiation has a characteristic range of wavelengths. The longer the wavelength (or the more stretched out it appears), the less energy is carried. Short, tight waves carry the most energy. This may seem illogical, but think of it in terms of a piece of moving rope. It takes little effort by a person to move a rope in long, wide waves. To make a rope move in short, tight waves, a person would need to apply significantly more energy.

The sun emits (Figure 11) a broad range of electromagnetic radiation, including X-rays and ultraviolet (UV) rays. The higher-energy waves are dangerous to living things; for example, X-rays and UV rays can be harmful to humans.

Absorption of Light

Light energy enters the process of photosynthesis when pigments absorb the light. In plants, pigment molecules absorb only visible light for photosynthesis. The visible light seen by humans as white light actually exists in a rainbow of colors. Certain objects, such as a prism or a drop of water, disperse white light to reveal these colors to the human eye. The visible light portion of the electromagnetic spectrum is perceived by the human eye as a rainbow of colors, with violet and blue having shorter wavelengths and, therefore, higher energy. At the other end of the spectrum toward red, the wavelengths are longer and have lower energy.

Understanding Pigments

Different kinds of pigments exist, and each absorbs only certain wavelengths (colors) of visible light. Pigments reflect the color of the wavelengths that they cannot absorb.

All photosynthetic organisms contain a pigment called chlorophyll a , which humans see as the common green color associated with plants. Chlorophyll a absorbs wavelengths from either end of the visible spectrum (blue and red), but not from green. Because green is reflected, chlorophyll appears green.

Other pigment types include chlorophyll b (which absorbs blue and red-orange light) and the carotenoids. Each type of pigment can be identified by the specific pattern of wavelengths it absorbs from visible light, which is its absorption spectrum.

Many photosynthetic organisms have a mixture of pigments; between them, the organism can absorb energy from a wider range of visible-light wavelengths. Not all photosynthetic organisms have full access to sunlight. Some organisms grow underwater where light intensity decreases with depth, and certain wavelengths are absorbed by the water. Other organisms grow in competition for light. Plants on the rainforest floor must be able to absorb any bit of light that comes through, because the taller trees block most of the sunlight (Figure 12).

The Light-Dependent Reactions of Photosynthesis

The overall purpose of the light-dependent reactions is to convert light energy into chemical energy. This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules.

The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. Photosystems exist in the membranes of thylakoids. A pigment molecule in the photosystem absorbs one photon, a quantity or “packet” of light energy, at a time.

A photon of light energy travels until it reaches a pigment molecule, such as chlorophyll. The photon causes an electron in the chlorophyll to become “excited.” The energy given to the electron then travels from one pigment molecule to another until it reaches a pair of chlorophyll a molecules called the reaction center. This energy then excites an electron in the reaction center causing it to break free and be passed to the primary electron acceptor. The reaction center is therefore said to “donate” an electron to the primary electron acceptor (Figure 13).

To replace the electron in the reaction center, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O 2 ) and hydrogen ions (H + ) in the thylakoid space. Technically, each breaking of a water molecule releases a pair of electrons, and therefore can replace two donated electrons.

The replacing of the electron enables the reaction center to respond to another photon. The oxygen molecules produced as byproducts find their way to the surrounding environment. The hydrogen ions play critical roles in the remainder of the light-dependent reactions.

Keep in mind that the purpose of the light-dependent reactions is to convert solar energy into chemical carriers that will be used in the Calvin cycle. In eukaryotes, two photosystems exist, the first is called photosystem II, which is named for the order of its discovery rather than for the order of function.

After the photon hits, photosystem II transfers the free electron to the first in a series of proteins inside the thylakoid membrane called the electron transport chain. As the electron passes along these proteins, energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space. This is quite analogous to the process that occurs in the mitochondrion in which an electron transport chain pumps hydrogen ions from the mitochondrial stroma across the inner membrane and into the intermembrane space, creating an electrochemical gradient. After the energy is used, the electron is accepted by a pigment molecule in the next photosystem, which is called photosystem I (Figure 14).

Generating an Energy Carrier: ATP

In the light-dependent reactions, energy absorbed by sunlight is stored by two types of energy-carrier molecules: ATP and NADPH. The energy that these molecules carry is stored in a bond that holds a single atom to the molecule. For ATP, it is a phosphate atom, and for NADPH, it is a hydrogen atom. NADH will be discussed further in relation to cellular respiration, which occurs in the mitochondrion, where it carries energy from the citric acid cycle to the electron transport chain. When these molecules release energy into the Calvin cycle, they each lose atoms to become the lower-energy molecules ADP and NADP + .

The buildup of hydrogen ions in the thylakoid space forms an electrochemical gradient because of the difference in the concentration of protons (H + ) and the difference in the charge across the membrane that they create. This potential energy is harvested and stored as chemical energy in ATP through chemiosmosis, the movement of hydrogen ions down their electrochemical gradient through the transmembrane enzyme ATP synthase, just as in the mitochondrion.

The hydrogen ions are allowed to pass through the thylakoid membrane through an embedded protein complex called ATP synthase. This same protein generated ATP from ADP in the mitochondrion. The energy generated by the hydrogen ion stream allows ATP synthase to attach a third phosphate to ADP, which forms a molecule of ATP in a process called photophosphorylation. The flow of hydrogen ions through ATP synthase is called chemiosmosis, because the ions move from an area of high to low concentration through a semi-permeable structure.

Generating Another Energy Carrier: NADPH

The remaining function of the light-dependent reaction is to generate the other energy-carrier molecule, NADPH. As the electron from the electron transport chain arrives at photosystem I, it is re-energized with another photon captured by chlorophyll. The energy from this electron drives the formation of NADPH from NADP + and a hydrogen ion (H + ). Now that the solar energy is stored in energy carriers, it can be used to make a sugar molecule.

In the first part of photosynthesis, the light-dependent reaction, pigment molecules absorb energy from sunlight. The most common and abundant pigment is chlorophyll a . A photon strikes photosystem II to initiate photosynthesis. Energy travels through the electron transport chain, which pumps hydrogen ions into the thylakoid space. This forms an electrochemical gradient. The ions flow through ATP synthase from the thylakoid space into the stroma in a process called chemiosmosis to form molecules of ATP, which are used for the formation of sugar molecules in the second stage of photosynthesis. Photosystem I absorbs a second photon, which results in the formation of an NADPH molecule, another energy carrier for the Calvin cycle reactions.

Describe the pathway of energy in light-dependent reactions.

The energy is present initially as light. A photon of light hits chlorophyll, causing an electron to be energized. The free electron travels through the electron transport chain, and the energy of the electron is used to pump hydrogen ions into the thylakoid space, transferring the energy into the electrochemical gradient. The energy of the electrochemical gradient is used to power ATP synthase, and the energy is transferred into a bond in the ATP molecule. In addition, energy from another photon can be used to create a high-energy bond in the molecule NADPH.

The Calvin Cycle

After the energy from the sun is converted and packaged into ATP and NADPH, the cell has the fuel needed to build food in the form of carbohydrate molecules. The carbohydrate molecules made will have a backbone of carbon atoms. Where does the carbon come from? The carbon atoms used to build carbohydrate molecules comes from carbon dioxide, the gas that animals exhale with each breath. The Calvin cycle is the term used for the reactions of photosynthesis that use the energy stored by the light-dependent reactions to form glucose and other carbohydrate molecules. This process may also be called the light-independent reaction, as it does not directly require sunlight (but it does require the products produced from the light-dependent reactions).

The Innerworkings of the Calvin Cycle

In plants, carbon dioxide (CO 2 ) enters the chloroplast through the stomata and diffuses into the stroma of the chloroplast—the site of the Calvin cycle reactions where sugar is synthesized. The reactions are named after the scientist who discovered them, and reference the fact that the reactions function as a cycle. Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery (Figure 15).

The Calvin cycle reactions (Figure 16) can be organized into three basic stages: fixation, reduction, and regeneration. In the stroma, in addition to CO 2 , two other chemicals are present to initiate the Calvin cycle: an enzyme abbreviated RuBisCO, and the molecule ribulose bisphosphate (RuBP). RuBP has five atoms of carbon and a phosphate group on each end.

RuBisCO catalyzes a reaction between CO 2 and RuBP, which forms a six-carbon compound that is immediately converted into two three-carbon compounds. This process is called carbon fixation, because CO 2 is “fixed” from its inorganic form into organic molecules.

ATP and NADPH use their stored energy to convert the three-carbon compound, 3-PGA, into another three-carbon compound called G3P. This type of reaction is called a reduction reaction, because it involves the gain of electrons. A reduction is the gain of an electron by an atom or molecule. The molecules of ADP and NAD + , resulting from the reduction reaction, return to the light-dependent reactions to be re-energized.

One of the G3P molecules leaves the Calvin cycle to contribute to the formation of the carbohydrate molecule, which is commonly glucose (C 6 H 12 O 6 ). Because the carbohydrate molecule has six carbon atoms, it takes six turns of the Calvin cycle to make one carbohydrate molecule (one for each carbon dioxide molecule fixed). The remaining G3P molecules regenerate RuBP, which enables the system to prepare for the carbon-fixation step. ATP is also used in the regeneration of RuBP.

In summary, it takes six turns of the Calvin cycle to fix six carbon atoms from CO 2 . These six turns require energy input from 12 ATP molecules and 12 NADPH molecules in the reduction step and 6 ATP molecules in the regeneration step.

Check out this animation of the Calvin cycle . Click Stage 1, Stage 2, and then Stage 3 to see G3P and ATP regenerate to form RuBP.

The shared evolutionary history of all photosynthetic organisms is conspicuous, as the basic process has changed little over eras of time. Even between the giant tropical leaves in the rainforest and tiny cyanobacteria, the process and components of photosynthesis that use water as an electron donor remain largely the same. Photosystems function to absorb light and use electron transport chains to convert energy. The Calvin cycle reactions assemble carbohydrate molecules with this energy.

However, as with all biochemical pathways, a variety of conditions leads to varied adaptations that affect the basic pattern. Photosynthesis in dry-climate plants (Figure 17) has evolved with adaptations that conserve water. In the harsh dry heat, every drop of water and precious energy must be used to survive. Two adaptations have evolved in such plants. In one form, a more efficient use of CO 2 allows plants to photosynthesize even when CO 2 is in short supply, as when the stomata are closed on hot days. The other adaptation performs preliminary reactions of the Calvin cycle at night, because opening the stomata at this time conserves water due to cooler temperatures. In addition, this adaptation has allowed plants to carry out low levels of photosynthesis without opening stomata at all, an extreme mechanism to face extremely dry periods.

Photosynthesis in Prokaryotes

The two parts of photosynthesis—the light-dependent reactions and the Calvin cycle—have been described, as they take place in chloroplasts. However, prokaryotes, such as cyanobacteria, lack membrane-bound organelles. Prokaryotic photosynthetic autotrophic organisms have infoldings of the plasma membrane for chlorophyll attachment and photosynthesis (Figure 18). It is here that organisms like cyanobacteria can carry out photosynthesis.

Using the energy carriers formed in the first stage of photosynthesis, the Calvin cycle reactions fix CO 2 from the environment to build carbohydrate molecules. An enzyme, RuBisCO, catalyzes the fixation reaction, by combining CO 2 with RuBP. The resulting six-carbon compound is broken down into two three-carbon compounds, and the energy in ATP and NADPH is used to convert these molecules into G3P. One of the three-carbon molecules of G3P leaves the cycle to become a part of a carbohydrate molecule. The remaining G3P molecules stay in the cycle to be formed back into RuBP, which is ready to react with more CO 2 . Photosynthesis forms a balanced energy cycle with the process of cellular respiration. Plants are capable of both photosynthesis and cellular respiration, since they contain both chloroplasts and mitochondria.

Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?

None of the cycle could take place, because RuBisCO is essential in fixing carbon dioxide. Specifically, RuBisCO catalyzes the reaction between carbon dioxide and RuBP at the start of the cycle.

Now that we’ve learned about the different pieces of photosynthesis, let’s put it all together. This video walks you through the process of photosynthesis as a whole:

Check Your Understanding

Answer the question(s) below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times.

Use this quiz to check your understanding and decide whether to (1) study the previous section further or (2) move on to the next section.

https://assessments.lumenlearning.co...sessments/6880

Contributors and Attributions

• Introduction to Photosynthesis. Authored by : Shelli Carter and Lumen Learning. Provided by : Lumen Learning. License : CC BY: Attribution
• Photosystem figure. Authored by : Adapted by Stephen Snyder. License : CC BY: Attribution . License Terms : Derivative of OpenStax original work
• Concepts of Biology. Provided by : OpenStax CNX. Located at : http://cnx.org/contents/[email protected] . License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/contents/[email protected]
• Biology. Provided by : OpenStax CNX. Located at : http://cnx.org/contents/[email protected] . License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/contents/[email protected]
• Photosynthesis: Crash Course Biology #8. Authored by : CrashCourse. Located at : https://youtu.be/sQK3Yr4Sc_k . License : All Rights Reserved . License Terms : Standard YouTube License

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What Is the End Product of Photosynthesis?

Describe What a Photosystem Does for Photosynthesis

Humans and most other animals need certain things to survive. Oxygen is one of them, and the carbohydrate glucose is another. Fortunately for them, plants (and certain bacteria and algae) produce both of these as the result of a complex process known as photosynthesis.

The Formula

The formula associated with the process of photosynthesis is

6H 2 O + 6CO 2 = C 6 H 12 O 6 + 6O 2 .

This formula tells you is that six molecules of water plus six molecules of carbon dioxide will produce one molecule of glucose plus six molecules of oxygen. This entire process goes through two distinct stages before it is completed. The first stage is a light-dependent process and the second stage is a light-independent process.

Light Dependent

In the light-dependent process, the electrons of the chloroplasts (special organelles used to carry out photosynthesis) are excited into a higher energy state when they are bombarded with light. These excited electrons cause a series of reactions that produce adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). ATP and NADPH are then used to make carbon bonds in the light-independent process. Water molecules present in the light-dependent process are split. Their oxygen molecules are released into the atmosphere.

Light Independent

Recall the splitting of the water molecules in the light-dependent process that released oxygen molecules into the atmosphere. Since water is H 2 0, there is still a hydrogen atom remaining. This hydrogen atom is used in the light-independent process when plants take carbon dioxide from the atmosphere. The carbon dioxide and hydrogen become bound together through a process called carbon fixation, which forms a non-specific carbohydrate.

Photophosphorylation

Photophosphorylation is the process by which light energy produces NADPH. Special pigments found in the plant’s cells known as chlorophyll make this process possible. The two main types of chlorophyll are chlorophyll A and chlorophyll B. In simple terms, the electrons of water molecules present in chlorophyll B become excited by the presence of light. Chlorophyll B takes one of these excited electrons splitting the H 2 O molecule into H + and O -2 . O -2 is converted into O 2 and released into the atmosphere. The excited electron is attached to a primary electron receptor, and through a series of complex reactions forms NADPH. NADPH is the energy carrier used in carbon fixation.

The Calvin Cycle

Plants produce glucose in a process known as the Calvin cycle. The carbon dioxide captured in the light-independent process is processed in this cycle. For every six molecules of carbon dioxide captured and put into the cycle, one molecule of glucose is produced. The chemical that captures the carbon dioxide for use in the Calvin cycle is ribulose biphosphate.

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About the Author

Kelley Boles obtained his B.A. in writing from the University of Central Arkansas in 2005. He has been a freelance writer within his community ever since. His most ambitious project today has been the writing of a comprehensive assembly manual for BBQ smokers manufactured by Royal Oak Enterprises LLC.

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Photosynthesis powers our world, but what fuels this fundamental process?

Palo Alto, CA— It’s hard to overstate the importance of photosynthesis , the biochemical pathway by which plants, algae, and certain bacteria convert the Sun’s energy into the organic material that feeds the entire living biosphere. But there are still aspects of the photosynthetic function that scientists are working to understand. Expanding their knowledge could help improve agriculture and fight climate change.

Photosynthesis provides the foundation for life on Earth by making our atmosphere oxygen rich; it also sequesters carbon pollution from human activity and forms the basis of the food chain.

“On a molecular level, photosynthesis has two components,” explained Carnegie Science algae expert Adrien Burlacot. “There’s the sunlight-powered splitting of water molecules, which produces the energy molecules that are used by all cells, and the fixation of carbon dioxide from the atmosphere into organic material, or biomass, which consumes chemical energy.”

He added: “But there’s a disconnect that has caused decades of debate. This is because the chemical energy needed to power the second half of this process—the transformation of carbon dioxide into biomass—is different than the energy currency created by splitting water molecules. And the processes involved in converting the basic energy molecules into the energy used to synthesize sugars are still mysterious.”

When it comes to photosynthetic efficiency, organisms have wide variation in their capacity to transform sunlight into biomass. While a tree or a grass would typically be able to use between 0.5 and 1 percent of the sun’s energy, microalgae are able to use up to 5 percent of that energy.

“Photosynthesis in plants is very inefficient,” Burlacot added. “Because algae are much better at it, they hold important potential for understanding how to improve this fundamental process that underpins nearly every aspect of life on our planet.”

Part of the secret lies in algae harboring a special biochemical system for concentrating carbon dioxide within the photosynthetic apparatus. For the last couple of years, Burlacot’s lab has been investigating how algae power this carbon-concentrating ability by studying Chlamydomonas , a group of photosynthetic algae that are found around the globe in fresh and saltwater, moist soils, and even at the surface of snow. Recently, they expanded this to examine how the basic energy currency is converted to the chemical energy necessary for the carbon-fixation process itself in algae.

In a paper published in The Plant Cell , Burlacot’s team revealed that three biochemical energy circuits power carbon fixation in Chlamydomonas . Their work demonstrated that all three pathways can sustain high rates of sugar production. However, the three circuits were not all equally efficient.

“Two out of three pathways are wasting twice more energy than the most efficient one,” Burlacot said. “And—interestingly—the two most efficient pathways are not present in crop plants.”

Looking ahead, the group wants to elucidate the contributions of each of the three mechanisms and to build connections between these and similar pathways in other photosynthetic organisms. A big question remains on whether difference in photosynthetic efficiency between species could be related to the energy circuits that they are using.

“We are attempting to understand biochemical and biophysical steps of how algae capture carbon dioxide, which could enable us to improve the efficiency of important crop plants and to enhance carbon capture solutions,” Burlacot concluded. “More work is needed, and we are revealing the full story of how carbon fixation is fueled.”

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MSU Extension Fruit & Nuts

Grand rapids area tree fruit update – june 25, 2024.

Lindsay Brown <[email protected]> , Michigan State University Extension - June 25, 2024

A warm and wet week.

Weather update and IPM impacts

This past week has been exceptionally hot and wet with 2.46 inches of rain. This upcoming week is expected to cool off, but the rainy conditions will continue.

This weather has some integrated pest management (IPM) impacts to note. The high volume of rain has degraded spray residues, and the consistent rain and high winds will limit spray windows this week. However, Wednesday and Thursday (June 26-27) are predicted to be good spraying conditions with both clear skies and low winds.

The warm and wet conditions are ideal for disease growth. This will be especially important for fungal issues like secondary scab, fruit rots and summer diseases in apples. Additionally, between the hail and high wind conditions, this presents a potential for trauma blight, which will be discussed later in this article.

In cherries, this weather can exacerbate bacterial canker, cherry leaf spot and American Brown Rot. The volume of rain can also contribute to cracking in cherries as sweet cherry harvest continues this week.

On the insect front, these rain events are likely to cause an increase in Japanese beetle and rose chafer populations in the next week.

Crop update

Sweet cherry harvest is wrapping up in the area this week. Early peach varieties will be ready for harvest as early as next week.

Apples have moved into the cell expansion phase of growth. Please keep in mind that the recent rains and the associated potential runoff will likely have leached fertilizer out of the soils, especially mobile nutrients like nitrogen.

Growing degree day accumulation is now moving between third cover and fourth cover timing.

We typically report GDD accumulation starting at March 1, but this is not a typical year. We reached the required chilling hours on Jan. 15 to move into ecodormancy and start accumulating GDD. This means the heat we received in February mattered for this year’s crop. As such, I will be reporting GDD from Jan. 1 rather than March 1 this season.      

Disease update

We are now at the end of primary apple scab season. This was a tough season to control with consistently windy conditions and unreliably predicted rain events. We are seeing small amounts of secondary scab throughout the region now. Please be sure to thoroughly scout prior to stopping scab controls.

Below is the full report of my primary apple scab trapping for this season. If you are seeing secondary scab, please consider the predicted lesion dates compared to scouting reports to identify any holes in this spring’s spray program.

* = Light infection risk, ** = moderate infection risk, *** = heavy infection risk, no asterisk (*) = no infection risk.

Fire blight

The wind and potential hail from the storm today, June 25, can cause damage to the trees that will allow bacteria to enter and infect. This is called trauma blight. Prompt sprays after the storm will limit the development of disease. Consider streptomycin sprays. Agri-Mycin has a preharvest interval of 50 days, which should not interfere with apple harvest. The heat this week may result in russeting or phytotoxicity if copper sprays are used.

If you have any fire blight infections, please reach out to me at  [email protected] .  The Sundin lab is looking to sample different bacterial isolates throughout the state this year.   

Powdery mildew

The rain this week has reduced powdery mildew’s ability to spread in the air. However, once the rain clears, we will once again have consistent severe risk of powdery mildew development. At this point, the overwintering primary powdery mildew has ceased. However, this is a cyclic disease and if it has established a foothold it will continue to spread all summer long. While some powdery mildew won’t kill trees, it can rapidly get out of control and reduce photosynthesis throughout the canopy.

Start incorporating control measures for bitter rot and black rot now. Mummies and fallen fruit contain inoculum for this season. They are sporulating and infecting at this point in the season. Frogeye leaf spot from black rot is now visible across different blocks in the area. The rain and heat this week will be very beneficial to the spread of these diseases.

Sooty blotch and fly speck

While these two fungal diseases appear later in the growing season, their control window is now. Summer diseases need springtime control.

Cherry leaf spot

Cherry leaf spot is much more widespread than typical years, even in orchards with consistent programs. We are now seeing some early defoliation associated with cherry leaf spot, which can both harm this year’s crop and the overall tree health. Keep in mind that cherry leaf spot lesions look like small, reddish-purple dots (2-3 millimeters across). A key symptom is white, fluffy fungal growth on the underside of the lesions. These lesions can overtake leaves and lead to defoliation. We are especially seeing these symptoms in leaves that also have bacterial canker symptoms. While this disease is primarily thought of in tart cherry production, it can certainly impact sweet cherries too.

Bacterial canker of stone fruits

Bacterial canker of cherry (caused by Pseudomonas sp.) and bacterial canker of peach and plum (caused by Xanthomonas sp.) is popping up across the state this season. Both diseases are associated with shot hole in the leaves, brown dry lesions on the fruit and cankers in the trees. This can also be associated with gummosis production, which is a general stress response by the trees. If you are seeing infections now, consider summer pruning to remove developing cankers, copper sprays at leaf drop and dormant copper next spring.

American brown rot

Cracking from rain or wounding in sweet cherries leads to higher likelihood of American brown rot infection. As fruit get closer to harvest, susceptibility to brown rot increases. Consider if brown rot management is needed. Using Indar may not be effective, even at the highest labeled rate of 12 ounces per acre. Previous research and resistance screening of American brown rot isolates in west central and northwest regions found that most screened fungal isolates had functional resistance to Indar. Find more information about this study . Effective materials for managing American brown rot include Merivon, Miravis and Cevya. Full coverage of all rows will be important to manage this

Insect update

Spotted wing drosophila has high populations this year . The warm and wet conditions this spring following a mild winter are prime for spotted wing drosophila development. Additionally, the high wind conditions and rainfall have presented challenges for getting spotted wing drosophila treatments on this season. Please refer to “ The 2024 outlook for spotted wing drosophila in Michigan cherry orchards ” for more information on spotted wing drosophila and their control.

Please note that this weather is conducive with increased populations of Japanese beetles and rose chafers . We anticipate a spike in their populations in the next week.

Codling moth first emergence of second generation of adults is expected June 28. The larvae for this generation will finish hatching this week. Consider this article on codling moth management .

Obliquebanded leafroller adults are active this week. My date of sustained catch is June 10. As such, egg hatch is expected to begin June 21 with peak egg hatch on June 23. The populations are maintaining this week with the first emergence of second generation adults outside of the seven-day forecast range.

No green fruitworms were caught in my traps this week.

The second generation of oriental fruit moth is emerging with peak adult emergence from June 17–20. Peak egglaying was on June 22.

The second generation of spotted tentiform leafminers is high this week.

Potato leafhoppers are currently in the area in high quantities. Keep an eye out for them in sticky traps and on the undersides of leaves. Look out for V-shaped, burnt leaf margins or cupping of young terminal leaves.

Green apple aphids are present in some blocks this week.

Woolly apple aphid colonies are still active and growing in orchards.

San Jose scale crawlers are active in south Michigan this week. I expect crawlers are active in the area, but I have been catching only parasitoids. Keep in mind that controlling this round of San Jose scale crawlers will be easier than controlling future generations this summer.

European red mites are active in the area with visible bronzing in some blocks. If you have mite damage, be sure to stay on top of irrigation to limit stress in impacted trees.

For more information about regional reports, please visit the Michigan State University Extension website.

This article was published by Michigan State University Extension . For more information, visit https://extension.msu.edu . To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters . To contact an expert in your area, visit https://extension.msu.edu/experts , or call 888-MSUE4MI (888-678-3464).

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The sugarcane scpetc gene improves water-deficit and oxidative stress tolerance in transgenic tobacco plants.

1. Introduction

2. materials and methods, 2.1. gene expression in field-grown sugarcane plants, 2.2. scpetc protein sequence analysis, 2.3. construction of the scpetc overexpression vector, 2.4. plant material and growth conditions, 2.5. transformation of tobacco plants, 2.6. measurement of gas exchange, chlorophyll fluorescence, and p700 parameters, 2.7. quantification of chlorophyll degradation under oxidative stress and water deficit, 2.8. statistical analysis, 3.1. the sugarcane scpetc gene, 3.2. the development of scpetc-overexpressing plants is less affected by water deficit, 3.3. scpetc protects psii and psi activities in response to water deficit, 3.4. effect of water deficit on photosynthesis and water use efficiency, 3.5. scpetc overexpression protects chlorophyll and reduces oxidative stress damage, 4. discussion, 4.1. effect of scpetc on plant development under water deficit, 4.2. photosystems (psi and psii), 4.3. gas exchange, 4.4. water and oxidative stress, 5. conclusions, supplementary materials, author contributions, data availability statement, acknowledgments, conflicts of interest.

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Silva, C.R.L.; de Souza, C.B.; dos Santos, C.M.; Floreste, B.S.; Zani, N.C.; Hoshino-Bezerra, A.A.; Bueno, G.C.; Chagas, E.B.R.; Menossi, M. The Sugarcane ScPetC Gene Improves Water-Deficit and Oxidative Stress Tolerance in Transgenic Tobacco Plants. Agronomy 2024 , 14 , 1371. https://doi.org/10.3390/agronomy14071371

Silva CRL, de Souza CB, dos Santos CM, Floreste BS, Zani NC, Hoshino-Bezerra AA, Bueno GC, Chagas EBR, Menossi M. The Sugarcane ScPetC Gene Improves Water-Deficit and Oxidative Stress Tolerance in Transgenic Tobacco Plants. Agronomy . 2024; 14(7):1371. https://doi.org/10.3390/agronomy14071371

Silva, Carolina Ribeiro Liberato, César Bueno de Souza, Claudiana Moura dos Santos, Bruno Spinassé Floreste, Nicholas Camargo Zani, Andrea Akemi Hoshino-Bezerra, Giane Carolina Bueno, Eder Bedani Ruiz Chagas, and Marcelo Menossi. 2024. "The Sugarcane ScPetC Gene Improves Water-Deficit and Oxidative Stress Tolerance in Transgenic Tobacco Plants" Agronomy 14, no. 7: 1371. https://doi.org/10.3390/agronomy14071371

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