structure of cell essay

• History & Society
• Science & Tech
• Biographies
• Animals & Nature
• Geography & Travel
• Arts & Culture
• Games & Quizzes
• On This Day
• One Good Fact
• New Articles
• Lifestyles & Social Issues
• Philosophy & Religion
• Politics, Law & Government
• World History
• Health & Medicine
• Browse Biographies
• Birds, Reptiles & Other Vertebrates
• Bugs, Mollusks & Other Invertebrates
• Environment
• Fossils & Geologic Time
• Entertainment & Pop Culture
• Sports & Recreation
• Visual Arts
• Demystified
• Image Galleries
• Infographics
• Top Questions
• Britannica Kids
• Saving Earth
• Space Next 50
• Student Center
• Introduction & Top Questions
• The structure of biological molecules
• Photosynthesis: the beginning of the food chain
• ATP: fueling chemical reactions
• DNA: the genetic material
• RNA: replicated from DNA
• Intracellular communication
• Intercellular communication
• Membrane lipids
• Membrane proteins
• Membrane fluidity
• Membrane channels
• The glucose transporter
• The anion transporter
• Counter-transport
• Co-transport
• The sodium-potassium pump
• Calcium pumps
• Hydrogen ion pumps
• Endocytosis
• General functions and characteristics
• The vacuole
• The lysosome
• Microbodies
• The smooth endoplasmic reticulum
• The rough endoplasmic reticulum
• The Golgi apparatus
• Secretory vesicles
• Sorting of products by chemical receptors
• Nucleosomes: the subunits of chromatin
• Organization of chromatin fibre
• The nuclear envelope
• The structure of DNA
• Rearrangement and modification of DNA
• RNA synthesis
• Processing of mRNA
• Regulation of RNA synthesis
• Regulation of RNA after synthesis
• Mitochondrial and chloroplastic structure
• Formation of the electron donors NADH and FADH 2
• The electron-transport chain
• The chemiosmotic theory
• Trapping of light
• Fixation of carbon dioxide
• The mitochondrion and chloroplast as independent entities
• The endosymbiont hypothesis
• Actin filaments
• Microtubules
• Intermediate filaments
• Matrix polysaccharides
• Matrix proteins
• Cell-matrix interactions
• Tissue and species recognition
• Adhering junctions
• Tight junctions
• Gap junctions
• Types of chemical signaling
• Signal receptors
• Cellular response
• Mechanical properties of wall layers
• Plasmodesmata
• Oligosaccharides with regulatory functions
• Duplication of the genetic material
• Mitosis and cytokinesis
• Controlled proliferation
• Failure of proliferation control
• The differentiated state
• The process of differentiation
• Errors in differentiation
• The development of genetic information
• The development of metabolism
• Early observations
• The problem of the origin of cells
• The protoplasm concept
• Contribution of other sciences

What is a cell?

What is cell theory, what do cell membranes do.

Our editors will review what you’ve submitted and determine whether to revise the article.

• British Society for Cell Biology - What is a cell?
• MSD Manual - Consumer Version - Cells
• Chemistry LibreTexts - Cell Tutorial
• Roger Williams University Open Publishing - Introduction to Molecular and Cell Biology - Introduction to Cells
• National Center for Biotechnology Information - The Origin and Evolution of Cells
• University of Minnesota Libraries - The Science of Plants - Plant Cells and Tissues
• Biology LibreTexts - Cell Theory
• cell - Children's Encyclopedia (Ages 8-11)
• cell - Student Encyclopedia (Ages 11 and up)
• Table Of Contents

A cell is a mass of cytoplasm that is bound externally by a cell membrane . Usually microscopic in size, cells are the smallest structural units of living matter and compose all living things. Most cells have one or more nuclei and other organelles that carry out a variety of tasks. Some single cells are complete organisms, such as a bacterium or yeast . Others are specialized building blocks of multicellular organisms , such as plants and animals .

Cell theory states that the cell is the fundamental structural and functional unit of living matter. In 1839 German physiologist  Theodor Schwann  and German botanist  Matthias Schleiden  promulgated that cells are the “elementary particles of organisms” in both plants and animals and recognized that some organisms are unicellular and others multicellular. This theory marked a great conceptual advance in biology and resulted in renewed attention to the living processes that go on in cells.

The cell membrane surrounds every living cell and delimits the cell from the surrounding environment. It serves as a barrier to keep the contents of the cell in and unwanted substances out. It also functions as a gate to both actively and passively move essential nutrients into the cell and waste products out of it. Certain proteins in the cell membrane are involved with cell-to-cell communication and help the cell to respond to changes in its environment.

cell , in biology , the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast . Other cells acquire specialized functions as they mature. These cells cooperate with other specialized cells and become the building blocks of large multicellular organisms, such as humans and other animals . Although cells are much larger than atoms , they are still very small. The smallest known cells are a group of tiny bacteria called mycoplasmas ; some of these single-celled organisms are spheres as small as 0.2 μm in diameter (1μm = about 0.000039 inch), with a total mass of 10 −14 gram—equal to that of 8,000,000,000 hydrogen atoms. Cells of humans typically have a mass 400,000 times larger than the mass of a single mycoplasma bacterium, but even human cells are only about 20 μm across. It would require a sheet of about 10,000 human cells to cover the head of a pin, and each human organism is composed of more than 30,000,000,000,000 cells.

This article discusses the cell both as an individual unit and as a contributing part of a larger organism. As an individual unit, the cell is capable of metabolizing its own nutrients , synthesizing many types of molecules, providing its own energy, and replicating itself in order to produce succeeding generations. It can be viewed as an enclosed vessel, within which innumerable chemical reactions take place simultaneously. These reactions are under very precise control so that they contribute to the life and procreation of the cell. In a multicellular organism , cells become specialized to perform different functions through the process of differentiation. In order to do this, each cell keeps in constant communication with its neighbours. As it receives nutrients from and expels wastes into its surroundings, it adheres to and cooperates with other cells. Cooperative assemblies of similar cells form tissues, and a cooperation between tissues in turn forms organs , which carry out the functions necessary to sustain the life of an organism.

Special emphasis is given in this article to animal cells, with some discussion of the energy-synthesizing processes and extracellular components peculiar to plants . (For detailed discussion of the biochemistry of plant cells, see photosynthesis . For a full treatment of the genetic events in the cell nucleus, see heredity .)

The nature and function of cells

A cell is enclosed by a plasma membrane , which forms a selective barrier that allows nutrients to enter and waste products to leave. The interior of the cell is organized into many specialized compartments, or organelles , each surrounded by a separate membrane. One major organelle , the nucleus , contains the genetic information necessary for cell growth and reproduction . Each cell contains only one nucleus, whereas other types of organelles are present in multiple copies in the cellular contents, or cytoplasm . Organelles include mitochondria , which are responsible for the energy transactions necessary for cell survival; lysosomes , which digest unwanted materials within the cell; and the endoplasmic reticulum and the Golgi apparatus , which play important roles in the internal organization of the cell by synthesizing selected molecules and then processing, sorting, and directing them to their proper locations. In addition, plant cells contain chloroplasts , which are responsible for photosynthesis, whereby the energy of sunlight is used to convert molecules of carbon dioxide (CO 2 ) and water (H 2 O) into carbohydrates . Between all these organelles is the space in the cytoplasm called the cytosol . The cytosol contains an organized framework of fibrous molecules that constitute the cytoskeleton , which gives a cell its shape, enables organelles to move within the cell, and provides a mechanism by which the cell itself can move. The cytosol also contains more than 10,000 different kinds of molecules that are involved in cellular biosynthesis , the process of making large biological molecules from small ones.

Specialized organelles are a characteristic of cells of organisms known as eukaryotes . In contrast, cells of organisms known as prokaryotes do not contain organelles and are generally smaller than eukaryotic cells. However, all cells share strong similarities in biochemical function.

The molecules of cells

Cells contain a special collection of molecules that are enclosed by a membrane. These molecules give cells the ability to grow and reproduce . The overall process of cellular reproduction occurs in two steps: cell growth and cell division . During cell growth, the cell ingests certain molecules from its surroundings by selectively carrying them through its cell membrane . Once inside the cell, these molecules are subjected to the action of highly specialized, large, elaborately folded molecules called enzymes . Enzymes act as catalysts by binding to ingested molecules and regulating the rate at which they are chemically altered. These chemical alterations make the molecules more useful to the cell. Unlike the ingested molecules, catalysts are not chemically altered themselves during the reaction, allowing one catalyst to regulate a specific chemical reaction in many molecules.

Biological catalysts create chains of reactions. In other words, a molecule chemically transformed by one catalyst serves as the starting material, or substrate, of a second catalyst and so on. In this way, catalysts use the small molecules brought into the cell from the outside environment to create increasingly complex reaction products. These products are used for cell growth and the replication of genetic material. Once the genetic material has been copied and there are sufficient molecules to support cell division, the cell divides to create two daughter cells. Through many such cycles of cell growth and division, each parent cell can give rise to millions of daughter cells, in the process converting large amounts of inanimate matter into biologically active molecules.

• Biology Article

Cells are the basic, fundamental unit of life. So, if we were to break apart an organism to the cellular level, the smallest independent component that we would find would be the cell.

Explore the cell notes to know what is a cell, cell definition, cell structure, types and functions of cells. These notes have an in-depth description of all the concepts related to cells.

Table of Contents

Cell Definition

What is a cell, characteristics of cells, types of cells, cell structure, cell theory.

• Functions of a Cell

Cells are the fundamental unit of life. They range in size from 0.0001 mm to nearly 150 mm across.

“A cell is defined as the smallest, basic unit of life that is responsible for all of life’s processes.”

Cells are the structural, functional, and biological units of all living beings. A cell can replicate itself independently. Hence, they are known as the building blocks of life . 

Each cell contains a fluid called the cytoplasm, which is enclosed by a membrane. Also present in the cytoplasm are several biomolecules like proteins, nucleic acids and lipids. Moreover, cellular structures called cell organelles are suspended in the cytoplasm.

A cell is the structural and fundamental unit of life. The study of cells from its basic structure to the functions of every cell organelle is called Cell Biology. Robert Hooke was the first Biologist who discovered cells.

All organisms are made up of cells. They may be made up of a single cell (unicellular), or many cells (multicellular).  Mycoplasmas are the smallest known cells. Cells are the building blocks of all living beings. They provide structure to the body and convert the nutrients taken from the food into energy.

Cells are complex and their components perform various functions in an organism. They are of different shapes and sizes, pretty much like bricks of the buildings. Our body is made up of cells of different shapes and sizes.

Cells are the lowest level of organisation in every life form. From organism to organism, the count of cells may vary. Humans have more number of cells compared to that of  bacteria .

Cells comprise several cell organelles that perform specialised functions to carry out life processes. Every organelle has a specific structure. The hereditary material of the organisms is also present in the cells.

Discovery of Cells

Discovery of cells is one of the remarkable advancements in the field of science. It helps us know that all the organisms are made up of cells, and these cells help in carrying out various life processes. The structure and functions of cells helped us to understand life in a better way.

Who discovered cells?

Robert Hooke discovered the cell in 1665. Robert Hooke observed a piece of bottle cork under a compound microscope and noticed minuscule structures that reminded him of small rooms. Consequently, he named these “rooms” as cells. However, his compound microscope had limited magnification, and hence, he could not see any details in the structure. Owing to this limitation, Hooke concluded that these were non-living entities.

Later Anton Van Leeuwenhoek observed cells under another compound microscope with higher magnification. This time, he had noted that the cells exhibited some form of movement (motility). As a result, Leeuwenhoek concluded that these microscopic entities were “alive.” Eventually, after a host of other observations, these entities were named as animalcules.

In 1883, Robert Brown, a Scottish botanist, provided the very first insights into the cell structure. He was able to describe the nucleus present in the cells of orchids.

Following are the various essential characteristics of cells:

• Cells provide structure and support to the body of an organism.
• The cell interior is organised into different individual organelles surrounded by a separate membrane.
• The nucleus (major organelle) holds genetic information necessary for reproduction and cell growth.
• Every cell has one nucleus and membrane-bound organelles in the cytoplasm.
• Mitochondria, a double membrane-bound organelle is mainly responsible for the energy transactions vital for the survival of the cell.
• Lysosomes digest unwanted materials in the cell.
• Endoplasmic reticulum plays a significant role in the internal organisation of the cell by synthesising selective molecules and processing, directing and sorting them to their appropriate locations.

Also Read : Nucleus

Cells are similar to factories with different labourers and departments that work towards a common objective. Various types of cells perform different functions. Based on cellular structure, there are two types of cells:

• Prokaryotes

Explore:   Difference Between Prokaryotic and Eukaryotic Cells

Prokaryotic Cells

Main article: Prokaryotic Cells

• Prokaryotic cells have no nucleus. Instead, some prokaryotes such as bacteria have a region within the cell where the genetic material is freely suspended. This region is called the nucleoid.
• They all are single-celled microorganisms. Examples include archaea, bacteria, and cyanobacteria.
• The cell size ranges from 0.1 to 0.5 µm in diameter.
• The hereditary material can either be DNA or RNA.
• Prokaryotes generally reproduce by binary fission, a form of asexual reproduction. They are also known to use conjugation – which is often seen as the prokaryotic equivalent to sexual reproduction (however, it is NOT sexual reproduction).

Eukaryotic Cells

Main article : Eukaryotic Cells

• Eukaryotic cells are characterised by a true nucleus.
• The size of the cells ranges between 10–100 µm in diameter.
• This broad category involves plants, fungi, protozoans, and animals.
• The plasma membrane is responsible for monitoring the transport of nutrients and electrolytes in and out of the cells. It is also responsible for cell to cell communication.
• They reproduce sexually as well as asexually.
• There are some contrasting features between plant and animal cells. For eg., the plant cell contains chloroplast, central vacuoles, and other plastids, whereas the animal cells do not.

The cell structure comprises individual components with specific functions essential to carry out life’s processes. These components include- cell wall, cell membrane, cytoplasm, nucleus, and cell organelles. Read on to explore more insights on cell structure and function.

Cell Membrane

• The cell membrane supports and protects the cell. It controls the movement of substances in and out of the cells. It separates the cell from the external environment. The cell membrane is present in all the cells.
• The cell membrane is the outer covering of a cell within which all other organelles, such as the cytoplasm and nucleus, are enclosed. It is also referred to as the plasma membrane.
• By structure, it is a porous membrane (with pores) which permits the movement of selective substances in and out of the cell.  Besides this, the cell membrane also protects the cellular component from damage and leakage.
• It forms the wall-like structure between two cells as well as between the cell and its surroundings.
• Plants are immobile, so their cell structures are well-adapted to protect them from external factors. The cell wall helps to reinforce this function.
• The cell wall is the most prominent part of the plant’s cell structure. It is made up of cellulose, hemicellulose and pectin.
• The cell wall is present exclusively in plant cells. It protects the plasma membrane and other cellular components. The cell wall is also the outermost layer of plant cells.
• It is a rigid and stiff structure surrounding the cell membrane.
• It provides shape and support to the cells and protects them from mechanical shocks and injuries.
• The cytoplasm is a thick, clear, jelly-like substance present inside the cell membrane.
• Most of the chemical reactions within a cell take place in this cytoplasm.
• The cell organelles such as endoplasmic reticulum, vacuoles, mitochondria, ribosomes, are suspended in this cytoplasm.
• The nucleus contains the hereditary material of the cell, the DNA.
• It sends signals to the cells to grow, mature, divide and die.
• The nucleus is surrounded by the nuclear envelope that separates the DNA from the rest of the cell.
• The nucleus protects the DNA  and is an integral component of a plant’s cell structure.

Cell Organelles

Cells are composed of various cell organelles that perform certain specific functions to carry out life’s processes. The different cell organelles, along with its principal functions, are as follows:

Cell Theory was proposed by the German scientists,  Theodor Schwann, Matthias Schleiden, and Rudolf Virchow. The cell theory states that:

• All living species on Earth are composed of cells.
• A cell is the basic unit of life.
• All cells arise from pre-existing cells.

A modern version of the cell theory was eventually formulated, and it contains the following postulates:

• Energy flows within the cells.
• Genetic information is passed on from one cell to the other.
• The chemical composition of all the cells is the same.

Functions of Cell

A cell performs major functions essential for the growth and development of an organism. Important functions of cell are as follows:

Provides Support and Structure

All the organisms are made up of cells. They form the structural basis of all the organisms. The cell wall and the cell membrane are the main components that function to provide support and structure to the organism. For eg., the skin is made up of a large number of cells. Xylem present in the vascular plants is made of cells that provide structural support to the plants.

Facilitate Growth Mitosis

In the process of mitosis, the parent cell divides into the daughter cells. Thus, the cells multiply and facilitate the growth in an organism.

Allows Transport of Substances

Various nutrients are imported by the cells to carry out various chemical processes going on inside the cells. The waste produced by the chemical processes is eliminated from the cells by active and passive transport. Small molecules such as oxygen, carbon dioxide, and ethanol diffuse across the cell membrane along the concentration gradient. This is known as passive transport. The larger molecules diffuse across the cell membrane through active transport where the cells require a lot of energy to transport the substances.

Energy Production

Cells require energy to carry out various chemical processes. This energy is produced by the cells through a process called   photosynthesis in plants and respiration in animals.

Aids in Reproduction

A cell aids in reproduction through the processes called mitosis and meiosis. Mitosis is termed as the asexual reproduction where the parent cell divides to form daughter cells. Meiosis causes the daughter cells to be genetically different from the parent cells.

Thus, we can understand why cells are known as the structural and functional unit of life. This is because they are responsible for providing structure to the organisms and perform several functions necessary for carrying out life’s processes.

Also Read:  Difference Between Plant Cell and Animal Cell

To know more about what is a cell, its definition, cell structure, types of cells, the discovery of cells, functions of cells or any other related topics, explore  BYJU’S Biology . Alternatively, download BYJU’S app for a personalised learning experience.

Frequently Asked Questions

1. what is a cell, 2. state the characteristics of cells..

• Cells provide the necessary structural support to an organism.
• The genetic information necessary for reproduction is present within the nucleus.
• Structurally, the cell has cell organelles which are suspended in the cytoplasm.
• Mitochondria is the organelle responsible for fulfilling the cell’s energy requirements.
• Lysosomes digest metabolic wastes and foreign particles in the cell.
• Endoplasmic reticulum synthesises selective molecules and processes them, eventually directing them to their appropriate locations.

3. Highlight the cell structure and its components.

The cell structure comprises several individual components which perform specific functions essential to carry out life processes. The components of the cell are as follows:

• Cell membrane
• Nuclear membrane
• Endoplasmic reticulum
• Golgi Bodies
• Mitochondria
• Chloroplast

4. State the types of cells.

Cells are primarily classified into two types, namely

• Prokaryotic cells
• Eukaryotic cells

5. Elaborate Cell Theory.

Cell Theory was proposed by  Matthias Schleiden, Theodor Schwann, and Rudolf Virchow, who were German scientists. The cell theory states that:

6. What is the function of mitochondria in the cells?

7. what are the functions of the cell.

The essential functions of the cell include:

• The cell provides support and structure to the body.
• It facilitates growth by mitosis.
• It helps in reproduction.
• Provides energy and allows the transport of substances.

8. What is the function of Golgi bodies?

9. who discovered the cell and how, 10. name the cell organelle that contains hydrolytic enzymes capable of breaking down organic matter., 11. which cellular structure regulates the entry and exit of molecules to and from the cell.

Register at BYJU’S for cell related Biology notes. Refer to these notes for reference.

Further Reading:  Cell Biology MCQs

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

Visit BYJU’S for all Biology related queries and study materials

Your result is as below

Request OTP on Voice Call

Leave a Comment Cancel reply

Your Mobile number and Email id will not be published. Required fields are marked *

Post My Comment

Nice note given in this context

Yes, it’s really helpful as it is clear and simple to understand

Nice note was given in this context…

useful details thanks

I love the content of the notes

It is very useful notes

ok thank you

Yes its very useful

these notes are very helpful in my preparation .but i also wants mcqs for cell biology kindly help me

Thank you for helping me 👼👼

THIS HELPS ME SO MUCH IN SCHOOL THANK YOU!!!!!!!!!!!!

Nice note and it helps a lot

Awesome explanation. It was really helpful for my exam preparation

It is very useful

easy to understand

These notes are very beautiful for our helping

This is very beautiful notes for our helping

Nice note in the context for our exam preparation

It is very important notes thanks for helping me

I like this upload more so other too can study as well

Really appreciate this it is well understanding and readable

Awesome points for this topic

Excellent lecture / notes

I really appreciate the notes

Amazing points. It’s also very useful.

wonderful material thanks for sharing

Yep they are, I like them

This is really informative

Perfect notes about cell and their component so thanks very much😊

nice work done on these notes

Nice presentation on cells

I must say very helpful insight . Thank you for your contribution to the community.

These notes are really effective and presentation of cell is nicely designed

Thank You Byjus for explaining topics in detail. By this I can understand the concepts easily 😄

That’s great

Thank you for explaining about cells in very simple and understanding way☺️.

very good presentation

REALLY NICE NOTES IT REALLY HELP ME A LOT IN SCHOOL AND EXTRA ACTIVITIES LIKE SO ON. I REALLY GOT TO CATCH UP ON WHAT I MISSED OUT IN SCIENCE ALTHOUGHT I DON’T LIKE SCIENCE

Thanks, it helped in my holiday homework. 🙂

This notes are very usefull to me Its easy to understand and i get evry point related to any topic thank you byju’s !

Really good that help me and I have taken the app also

very good notes very useful

This is realy usefull i like this

Thank you I got all the points for the project from this Byjus

Very useful during the exam. Should study from this app #learning with Byju’s

This helps me to understand the following chapters

This point really helps me to understand the lesson

Good notes, very useful

splendiferous

Nice very nice

Wow, now I understand

very useful notes

IT HELPS TO KNOW EVERYTHING

Very beautiful and useful notes

Awesome explanation

I am very happy with this website

I am grateful for the notes, It was really informative and readable.

Very good explanation

Great notes

Thanks for your help

Thanks alot Really nice notes

A good, perfect, conceptual notes provided by the world’s no. 1 and most loved learning app that is BYJU’S The Learning App. That notes helps me about the cell after pair the app with this notes and understand perfect. Thank you!

Thanks. It’s very useful

Really excited with the explanation

Wow, really I am understanding very well how you explain the lesson

Comfortable and so understanding points, topics and questions are given in Byjus app

Very helpful

Thanks to you all. it’s very helpful 😍😊😃

The diagram and the keynotes were understandable, and it’s useful

Thanks for this note, it is really helpful to me

Thanks for this note, it’s very helpful and interesting

First of all honestly, cell was a chapter completely beyond my understandings. I studied hard but I was just unable to remember the concepts. I was just confused in words like lysozome n rybozome. SER n RER. But today I mastered this chapter completely with the help of Byju’s. I also tried to learn beyond my consepts. I was like asking the same question to my mentor again n again. But she never got frustrated and also explained me each n every consept. For me Byju’s is best way to learn only for those who really wanna learn. From my side:- Dream it- work hard – make it happen. Best wishes to all of you.

Hi students and teachers I love notes

Very useful

Register with BYJU'S & Download Free PDFs

Register with byju's & watch live videos.

• $ 0.00 0 items

Introduction to cells

All living things are made from one or more cells. A cell is the simplest unit of life and they are responsible for keeping an organism alive and functioning. This introduction to cells is the starting point for the area of biology that studies the various types of cells and how they work.

There is a massive variety of different types of cells but they all have some common characteristics. Almost every different type of cell contains genetic material , a membrane and cytoplasm. Cells also have many other features such as organelles and ribosomes that perform specific functions.

Many different organisms on the tree of life contain only one cell and are known as single-celled or unicellular organisms. Their single cell performs all the necessary functions to keep the organism alive. All species of bacteria and archaea are single-celled organisms. On the other hand, large organisms like humans are made from many trillions of cells that work together to keep the organism alive.

The most basic categorisation of Earth’s organisms is determined by different types of cells. All cells can be divided into one of two classifications: prokaryotic cells and eukaryotic cells. Prokaryotic cells are found in bacteria and archaea. Eukaryotic cells are found in organisms from the domain Eukaryota which includes animals, plants, fungi and protists.

This introduction to cells will take you through the basic structure of cells, the difference between prokaryotic and eukaryotic cells and you will learn about organelles.

STRUCTURE OF A CELL

The genetic material of cells is found as molecules called DNA. The DNA of a cell holds all the information that a cell needs to keep itself alive. A DNA molecule contains a code that can be translated by a cell and tells it how to perform different tasks. A gene is a specific segment of a DNA molecule and each gene tells a cell how to perform one specific task.

The gel-like substance that the genetic material is found in is called the cytoplasm. The cytoplasm fills a cell and gives it it’s shape. The cytoplasm also allows for different materials to move around the cell. All cells have other structures in their cytoplasm that help the cell stay alive.

The cytoplasm of all cells is surrounded by a membrane called the plasma membrane. The plasma membrane separates the cell from the outside world and keeps the contents of the cell together. The plasma membrane provides a barrier that substances have to pass through before they can enter or exit a cell.

EUKARYOTIC CELLS VS. PROKARYOTIC CELLS

The main difference between prokaryotic cells and eukaryotic cells is the presence of a nucleus and organelles. Prokaryotic cells do not have either a nucleus or organelles. The word prokaryotic can be translated to mean ‘before nucleus’.

Eukaryotic cells have both a nucleus and a range of different organelles. The nucleus is a structure found in eukaryotic cells that contains the cell’s DNA. Organelles are cellular ‘factories’ that perform important functions such as building different molecules of life , removing wastes and breaking down sugars.

Having organelles makes eukaryotic cells much more efficient at completing important cellular functions. Because they are more efficient, eukaryotic cells can grow much larger than prokaryotic cells.

For a cellular structure to be considered an organelle it must be surrounded by a membrane just as the nucleus is. Prokaryotic cells contain various structures that help with certain functions, such as ribosomes, but these structures are not encapsulated by membranes and are therefore not considered organelles.

Eukaryotic cells have evolved into multicellular organisms. By specializing into different types of cells, they are able to perform functions even more efficiently and are able to keep large, multicellular organisms alive.

Important organelles include the nucleus, mitochondria, chloroplasts, and the endoplasmic reticulum. Mitochondria are involved in the process of cellular respiration where sugar is broken down and converted into cellular energy.

Chloroplasts are found in the cells of plants and other photosynthetic organisms . Inside chloroplasts are where plant cells are able to use energy from the sun to create sugars from carbon dioxide and water.

The endoplasmic reticulum is a network of membranes that are attached to the membrane of the nucleus. The endoplasmic reticulum is involved with many important tasks such as producing proteins and breaking down fats and carbohydrates.

For more information on cells check out these pages on our website: Cells | Eukaryotic cells | Prokaryotic cells | Animal cells | Plant cells

Last edited: 30 August 2020

eBook - $2.95

Also available from Amazon , Book Depository and all other good bookstores.

What does DNA stand for?

Know the answer? Why not test yourself with our quick 20 question quiz

• COVID-19 Tracker
• Biochemistry
• Anatomy & Physiology
• Microbiology
• Neuroscience
• Animal Kingdom
• NGSS High School
• Latest News
• Editors’ Picks
• Weekly Digest
• Quotes about Biology

Cell Structure

Reviewed by: BD Editors

Cells are the fundamental units of life from which all other living things are made. They contain all the molecules and structures needed for individual cell survival and the survival of the organism as a whole.

Different cells have different subcellular structures, but all eukaryotes contain the same three parts: the nucleus, the cell membrane, and the cytoplasm.

What is the Structure of Cells?

All eukaryotic cells consist of  three basic parts . These are the cell membrane, the nucleus, and the cytoplasm. The cell membrane surrounds the outside of the cell, the nucleus is found in the middle of the cell, and the cytoplasm fills the gap between the two. Buried in the cytoplasm are hundreds or thousands of subcellular structures called  organelles.   

The fluid inside cells is known as the  intracellular fluid (ICF),  while the environment outside of the cell is referred to as the  extracellular fluid (ECF).

The Cell Membrane

The cell membrane (AKA the plasma membrane) is a thin, flexible structure that surrounds the outside of the cell, creating a physical barrier between the cell interior and its external environment. It consists of a semipermeable lipid bilayer that regulates the passage of materials in and out of the cell.

The Cytoplasm

The cytoplasm is a jelly-like goo that fills the interior space of the cell. It cushions and protects the cell organelles and is also where many of the cell’s chemical reactions take place. The cytoplasm is mainly composed of water, but also contains salts and other organic molecules.

The Nucleus

The nucleus contains the cell’s DNA and genetic information. It is separated from the cytoplasm by a double membrane called the nuclear envelope and controls all cellular activities, including cell division, protein production, growth, and metabolism.

Cell Organelles

Organelles are the ‘tiny organs’ of a cell. They are distinct, specialized structures that are adapted to fulfill the essential life functions necessary for cell survival. Some organelles (for example, the mitochondria, ribosomes, and nucleus) are found in almost all cell types. Others (like the chloroplasts and cell wall) are only found in certain cell types, like plants and algae.

Animal Cell Organelles

Animal cell organelles are typically found in both animal and plant cells. They include mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, and lysosomes, as well as the nucleus, cytoplasm, and cell membrane.

Mitochondria

Mitochondria are the site of respiration in cells. They release the energy required to power all other cellular processes.

Ribosomes are where protein production takes place. These organelles ‘read’ the instructions contained in the genetic code and use them to assemble polypeptide chains from amino acids.

The Endoplasmic Reticulum

The ER is a  large, continuous, membrane-bound organelle  whose main functions are to process and transport newly-synthesized materials. The rough ER is studded with ribosomes and is used in the processing and transportation of proteins. The smooth ER has no ribosomes and is mainly involved in lipid and hormone synthesis.

Golgi Apparatus

Once materials leave the ER, they are sent to the Golgi apparatus where they are packaged and distributed to wherever they are needed. Some materials are incorporated into the plasma membrane, while others pass through the membrane and leave the cell.

Lysosomes are small, spherical organelles that use digestive enzymes to dispose of unwanted materials. They may be used to recycle old or damaged cell parts or invading pathogens, and also play a key role in  apoptosis  (programmed cell death).

Plant Cell Organelles

Some plant cell organelles are not found in animal cells. They include the chloroplasts, vacuole, and plant cell wall.

Chloroplasts

Chloroplasts are the site of photosynthesis, a process in which light energy from the sun is used to convert carbon dioxide and water into glucose. They are filled with a green pigment called chlorophyll, which harvests light energy and gives plants their green color.

The Vacuole

The vacuole is a large, sap-filled bubble that plant cells use to store water, proteins, and other molecules.

Another function of the vacuole is to maintain turgor pressure in plant cells, as this helps them to keep their shape and prevents wilting or bursting.

The Cell Wall

The cell wall surrounds plant cells, protecting and supporting the cell. This structure is mainly made of cellulose and is very strong.

Cite This Article

Subscribe to our newsletter, privacy policy, terms of service, scholarship, latest posts, white blood cell, t cell immunity, satellite cells, embryonic stem cells, popular topics, hydrochloric acid, pituitary gland, natural selection, homeostasis, photosynthesis.

Choose Your Test

• Search Blogs By Category
• College Admissions
• AP and IB Exams
• GPA and Coursework

What Is the Cell Theory? Why Is It Important?

General Education

If you’re studying biology, you’ll likely learn about the cell theory. The cell theory is one of the most important tenets of biology, and practically everything else you learn in science class relates back to it. But what is the cell theory? In this guide, we’ll give you a clear cell theory definition, explain key dates in the history of this theory, and explain why it’s so important to understand. After reading this guide, you’ll know everything you need to know about the cell theory!

Cell Theory Definition

What is the cell theory? It has three main parts:

1. All living things are made up of cells.

2. Cells are the basic building blocks of life.

3. All cells come from preexisting cells created through the process of cell division.

As science evolved, three more components were added to the theory. Some biology classes don’t require you to know these parts of the cell theory because they weren’t part of the original definition, but it’s still useful to be aware of them:

4. Energy flow occurs within cells.

5. Hereditary information is passed from cell to cell.

6. All cells have the same basic chemical composition.

So what does the cell theory actually mean? Let’s break it down. The first part of the cell theory states that all living things are made up of cells. Anything that’s alive, from bacteria to plants to humans, is composed of cells. And what are cells? The literal definition is a cell is a group of organelles surrounded by a thin membrane .

The cell theory definition states that cells are the building blocks of life. Cells both make up all living things and run the processes needed for life. Your hair, skin, organs, etc. are all made up of cells. In fact, each person is estimated to be made up of nearly 40 trillion cells! Each part of a cell has a different function, and your cells are responsible for taking in nutrients, turning nutrients into energy, removing waste, and more. Basically, everything your body does, it does because cells are directing the action!

The third part of the cell theory definition states that all cells come from preexisting cells. This means that cells don’t just appear out of thin air (known as “spontaneous generation”). New cells are always made from current cells. This means that all current life on the planet is descended from the very first cells, which first made an appearance on Earth roughly 3.5 billion years ago. Cells have been replicating themselves continuously ever since.

And what does the newer part of the cell theory state? Part four refers to the fact that, in all living cells, energy is continuously transformed from one type to another. Examples of these processes include photosynthesis (where plant cells convert light energy into chemical energy ) and cellular respiration (where both plant and animal cells convert glucose into energy). Part five refers to DNA and the fact it is passed from parent cell to child cell. Finally, part six of the cell theory tells us that all cells are made up of the same chemicals: water, inorganic ions, and organic molecules.

The History of the Cell Theory

The cell theory and ideas about cells and living things evolved over several centuries. Here are the key dates for the cell theory:

1665: Robert Hooke is the first person to observe cells when he looks at a slice of cork in a microscope.

1665: Francesco Redi disproves spontaneous generation by showing maggots will only grow on uncovered meat, not meat enclosed in a jar. His work later contributes to part three of the cell theory.

1670s: Antonie van Leeuwenhoek, a Dutch scientist, begins his work developing better microscopes that allow scientists to see cells and the organelles they contain more clearly.

1839: German scientists Matthias Schleiden and Theodor Schwann describe the first two parts of the cell theory. Schleiden stated that all plants are made up of cells, while Schwann stated all animals are made up of cells. Schleiden and Schwann are generally credited as the developers of cell theory.

1855: Rudolf Virchow, another German scientist, describes the third part of cell theory, that all cells come from existing cells.

Since then, microscopes have continued to become more and more refined, making it possible to study cells even more closely and allowing scientists to expand on the original cell theory.

How Is the Cell Theory Important for Biology?

You may be surprised by how obvious the cell theory seems. Anyone who’s taken a basic biology class already knows what cells are and that living things are made up of cells. However, that just goes to show how important the cell theory is. It’s one of the fundamental principles of biology, and it’s so important that it has become information many of us take for granted.

Knowing that all living things are made up of cells allows us to understand how organisms are created, grow, and die. That information helps us understand how new life is created, why organisms take the form they do, how cancer spreads, how diseases can be managed, and more. Cells even help us understand fundamental issues such as life and death: an organism whose cells are living is considered alive, while one whose cells are dead is considered dead.

Before the cell theory existed, people had a very different view of biology. Many believed in spontaneous generation, the idea that living organisms can arise from nonliving matter. An example of this would be a piece of rotten meat creating flies because flies often appear around rotten meat. Additionally, before cells and the cell theory were known, it wasn’t understood that humans, as well as all other living organisms, were made up of billions and trillions of tiny building blocks that controlled all our biological processes. Disease, how organisms grow, and death were much more of a mystery compared to what we know today. The cell theory fundamentally changed how we look at life.

Summary: What Is the Cell Theory?

The cell theory is one of the foundational theories of biology. It has three main components:

As our scientific knowledge has increased over time, additional parts have been added to the theory. Schleiden and Schwann, as well as Virchow, are generally seen as the founders of the cell theory, due to their pioneering scientific work in the 1800s. The cell theory is important because it affects nearly every aspect of biology, from our understanding of life and death, to how we manage diseases, and more.

What's Next?

Looking for more cell biology explanations? We have articles on everything from parts of the cell (like nucleotides and the endoplasmic reticulum ) to how mitosis works and how it's different from meiosis .

Are there other science topics you want to review? Then you're in luck!   Our guides will teach you loads of useful topics, including  how to convert Celsius to Fahrenheit  and what the density of water is .

What are the most important science classes to take in high school?  Check out our guide to learn all the high school classes you should be taking.

Are you learning about trig identities in your math classes? Learn all the trig identities that you must know by reading our guide!

Trending Now

How to Get Into Harvard and the Ivy League

How to Get a Perfect 4.0 GPA

How to Write an Amazing College Essay

What Exactly Are Colleges Looking For?

ACT vs. SAT: Which Test Should You Take?

When should you take the SAT or ACT?

Get Your Free

Find Your Target SAT Score

Free Complete Official SAT Practice Tests

How to Get a Perfect SAT Score, by an Expert Full Scorer

Score 800 on SAT Math

Score 800 on SAT Reading and Writing

How to Improve Your Low SAT Score

Score 600 on SAT Math

Score 600 on SAT Reading and Writing

Find Your Target ACT Score

Complete Official Free ACT Practice Tests

How to Get a Perfect ACT Score, by a 36 Full Scorer

Get a 36 on ACT English

Get a 36 on ACT Math

Get a 36 on ACT Reading

Get a 36 on ACT Science

How to Improve Your Low ACT Score

Get a 24 on ACT English

Get a 24 on ACT Math

Get a 24 on ACT Reading

Get a 24 on ACT Science

Stay Informed

Get the latest articles and test prep tips!

Christine graduated from Michigan State University with degrees in Environmental Biology and Geography and received her Master's from Duke University. In high school she scored in the 99th percentile on the SAT and was named a National Merit Finalist. She has taught English and biology in several countries.

Ask a Question Below

Have any questions about this article or other topics? Ask below and we'll reply!

• BiologyDiscussion.com
• Follow Us On:
• Google Plus
• Publish Now

Essay on Nucleus: Structure, Position and Functions

ADVERTISEMENTS:

In this essay we will discuss about:- 1. Definition of Nucleus 2. Number of Nucleus 3. Position 4. Shape 5. Biochemical Analysis 6. Structure 7. Functions.

• Essay on the Functions of Nucleus

Essay # 1. Definition of Nucleus:

Nucleus (L. nucleus- kernel) is a specialized double membrane bound protoplasmic body which contains all the genetic information for controlling cellular metabolism and transmission to the posterity.

A nucleus in the non-dividing or metabolic phase is called interphase nucleus. Like other cellular structures, living unstained nucleus does not show much internal differentiation. For detailed study of nucleus, the cells must be properly killed, fixed and stained.

Nucleus is the largest cell organelle. Though first observed by Leeuwenhoek in red blood cor­puscles of fish, nucleus was first studied in orchid root cells by Robert Brown in 1831.

A nucleus is present in all living eukaryotic cells with the excep­tion of mature sieve cells of vascular plants and red blood corpuscles of mammals. Even here a nucleus is present during the early stages of their development. Presence of hereditary information in the nucleus was proved by the work of Joachim Hammerling (1953) on single celled alga Acetabularia (Fig. 8.51).

Essay # 2. Number of Nucleus:

Commonly cells are uninucleate, that is, they possess a single nucleus. The protistan Paramecium caudatum has two nuclei (bi- nucleate), macronucleus for controlling metabolic activities of the organism and micronucleus pos­sessing hereditary information.

Multinucleate or polynucleate condition is found in some cells of bone marrow, striated muscles, latex vessels, sev­eral fungi and algae. Multinucleate animal or protistan cells are called syncytial cells (e.g., epider­mis of Ascaris) while in plants and fungi they are called coenocytic cells (e.g., Rhizopus, Vaucheria). Acellular slime moulds have a multinucleate proto­plasmic body called Plasmodium.

Essay # 3. Position of Nucleus:

Nucleus is usually found in the re­gion of maximum metabolic activity in the cyto­plasm. Commonly it is situated in the geometric centre of the cell. In plant cells it is pushed to peripheral position on one side due to the develop­ment of a large central vacuole. Nucleus is periph­eral in fat-storing cells or adipocytes, and basal in glandular cells. It is suspended in central vacuole by cytoplasmic strands in Spirogyra.

Essay # 4. Shape of Nucleus:

The nuclei are generally rounded in outline. They appear oval or elliptical in plant cells having large central vacuoles. Disc-shaped nuclei occur in the cells of squamous epithelium, lobed in white blood corpuscles and irregularly branched in silk spinning cells of insects.

Essay # 5. Biochemical Analysis of Nucleus:

DNA- 9-12%. RNA- 5%. Lipids- 3%. Basic Proteins- 15%. Acid proteins, neutral proteins and enzymes- 65%. Traces of minerals like Calcium, Mag­nesium, Potassium and Sodium (Phosphorus is a constituent of DNA, RNA and acid pro­teins).

Essay # 6. Structure of Nucleus:

A typical interphase nucleus is 5-25 pm in diameter. It is differentiated into five parts— nuclear envelope, nucleoplasm, nuclear matrix, chromatin and nucleolus (Fig. 8.53).

a. Nuclear Envelope (= Karyotheca):

It bounds the nucleus on the outside. The nuclear envelope separates the nucleus from the cytoplasm. It is made up of two lipoprotein and trilaminar membranes, each of which is 60-90A thick. The inner membrane is smooth.

The outer membrane may be smooth or its cytoplasmic surface may bear ribosomes like the rough endoplasmic reticulum. The two membranes of the nuclear envelope are separated by an electron transparent perinuclear space. The space is 100—500 A in width. The outer membrane is often connected to endoplasmic reticulum.

Nuclear envelope contains a large number of pores or perforations (Fig. 8.52). In some cases 10% of the envelope is occupied by pores. The two membranes of the envelope become continuous in the region of pores.

Nuclear pores have complex structure. They may have diaphragm, septum, plug of electron dense material or nucleoplasmin, blebs or annuli. Annuli are circular structures around the pores. The pores and their annuli form a pore complex called annulated pore.

An annulated nuclear pore may possess 9 cylinders, one central and eight peripheral. Instead, there may be a network of granules and filaments. The nuclear pores control the passage of substances to the inside or outside of the nucleus, e.g., RNAs, ribosomes, proteins.

b. Nucleoplasm (Nuclear Sap, Karyolymph, Strasburger, 1882):

It is a transparent, semifluid and colloidal substance which fills the nucleus. It contains nucleosides and a number of enzymes (e.g., DNA polymerase, RNA polymerase, nucleoside phosphorylase) which are required for the synthesis and functioning of DNA, RNA, nucleoproteins, etc. Some of the proteins present in nucleoplasm are essential for spindle formation.

c. Nuclear Matrix:

It is a network of fine fibrils of acid proteins that function as scaffold for chromatin. On the periphery, below the nuclear envelope, nuclear matrix forms a dense fibrous layer called nuclear lamina. Terminal ends of chromatin fibres or telomeres are embedded in nuclear or fibrous lamina. Nuclear matrix consists of two types of inter­mediate filaments, lamin A and lamin B.

Nuclear matrix and nuclear lamina form:

(i) Scaffold for chromatin,

(ii) Attachment sites to telomeric parts,

(iii) Mechanical strength to nuclear envelope, and

(iv) Components of nuclear pore complex.

d. Chromatin:

It is hereditary DNA-protein fibrillar complex which is named so be­cause of its ability to get stained with certain basic dyes. Chromatin occurs in the form of fine overlapping and coiled fibres which appear to produce a network called chromatin reticulum.

Chromatin fibres are distributed throughout the nucleoplasm. They are differentiated into two regions— euchromatin and heterochro­matin, Heitz (1928). Euchromatin is narrow (10-30nm thick) lightly stained and diffused fibrous part which forms the bulk of chromatin.

Heterochromatin is wider (100 nm thick), darkly stained and condensed granular part which is attached here and there on the euchro­matin. Depending upon the size of granules formed by heterochromatin they are called chromocentres, karyosomes or false nucleoli.

The whole of chromatin is not functional. Generally only a portion of euchromatin which is associated with acid proteins takes part in transcription or formation of RNAs. During prophase of nuclear division, the chromatin fibres condense to form a definite number of thread-like structures called chromosomes.

e. Nucleolus (plural-nucleoli):

It was first discovered by Fontana in 1781, described by Wagner in 1840 and provided with its present name by Bowman in 1840. Nucleolus is a naked, round or slightly irregular structure which is attached to the chromatin at a specific region called nucleolar organizer region (NOR).

Commonly 1-4 nucleoli are found in a nucleus. Up to 1600 nucleoli are reported in the oocytes of Xenopus. A covering membrane is absent around nucleolus. Calcium seems to be essential for maintaining its configuration. Nucleolus has four components— amorphous matrix, granular part, fibrillar portion and chromatin (Fig. 8.54).

(i) Amorphous Matrix:

It is the homoge­neous ground substance of the nucleolus. Matrix is formed of protein.

(ii) Granular Portion:

It consists of gran­ules of the size of 150-200 A which lie scattered in the amorphous matrix. The granules are formed of protein and RNA in the ratio of 2:1. They are believed to be precursors of ribosomes.

(iii) Fibrillar Portion (Nucleolonema):

It is formed of a large number of small fibrils that are 50—so A long. The fibrils are made up of both protein and RNA and are believed to be precursors of granules.

(iv) Chromatin Portion:

It is that part of chromatin which is associated with nucleolus. Depending upon its position nucleolar chromatin is of two types— perinucleolar and intra-nucleolar. The perinucleolar chromatin lies around the periphery of the nucleolus. It gives rise to ingrowths or trabeculae which produce the intra-nucleolar chromatin.

(i) Nucleolus is the principal site for the development of ribosomal RNAs.

(ii) It is the centre for the formation of ribosome components,

(iii) Nucleolus stores nucleoproteins. The same are synthesised in the cytoplasm (over the ribosomes) and transferred to nucleolus,

(iv) It is essential for spindle formation during nuclear division.

Essay # 7. Functions of Nucleus:

Nucleus is an essential and integral part of the eukaryote cell. It stores genetic information in its DNA molecules which can be passed on to daughter cells. It also controls cellular activities.

i. Chromatin:

Nucleus contains hereditary material called chromatin. Chromatin is DNA- protein complex. It is made of a number of fine fibres that condense to form chromosomes. Number of chromosomes is fixed for a species. They bear genes.

ii. Genetic Information:

Chromatin part of nucleus possesses all the genetic information that is required for growth and development of the organism, its reproduction, metabolism and behaviour.

iii. Cellular Activities:

Nucleus controls cell metabolism and other activities through the formation of RNAs (mRNA, rRNA, tRNA) which control synthesis of particular type of enzymes.

iv. Ribosomes:

Ribosomes are formed in nucleolus part of the nucleus.

v. Variations:

All variations are caused by changes in genetic material present in the nucleus.

vi. Cell Growth and Maintenance:

With the help of RNAs, nucleus directs the synthesis of some structural proteins and chemicals required for cell growth and maintenance.

vii. Cell Differentiation:

It directs cell differentiation by allowing certain particular sets of genes to operate.

viii. Cell Replication:

Replication of nucleus is essential for cell replication.

Related Articles:

• Structure of Nucleus (With Diagram) | Botany
• Nucleus of the Controlling Centre of Cell (With Diagram)

Biology , Cell , Cell Organelles , Essay , Essay on Nucleus

• Anybody can ask a question
• Anybody can answer
• The best answers are voted up and rise to the top

Forum Categories

• Animal Kingdom
• Biodiversity
• Biological Classification
• Biology An Introduction 11
• Biology An Introduction
• Biology in Human Welfare 175
• Biomolecules
• Biotechnology 43
• Body Fluids and Circulation
• Breathing and Exchange of Gases
• Cell- Structure and Function
• Chemical Coordination
• Digestion and Absorption
• Diversity in the Living World 125
• Environmental Issues
• Excretory System
• Flowering Plants
• Food Production
• Genetics and Evolution 110
• Human Health and Diseases
• Human Physiology 242
• Human Reproduction
• Immune System
• Living World
• Locomotion and Movement
• Microbes in Human Welfare
• Mineral Nutrition
• Molecualr Basis of Inheritance
• Neural Coordination
• Organisms and Population
• Photosynthesis
• Plant Growth and Development
• Plant Kingdom
• Plant Physiology 261
• Principles and Processes
• Principles of Inheritance and Variation
• Reproduction 245
• Reproduction in Animals
• Reproduction in Flowering Plants
• Reproduction in Organisms
• Reproductive Health
• Respiration
• Structural Organisation in Animals
• Transport in Plants
• Trending 14

Privacy Overview

Have a language expert improve your writing

Run a free plagiarism check in 10 minutes, generate accurate citations for free.

• Knowledge Base
• Example of a great essay | Explanations, tips & tricks

Example of a Great Essay | Explanations, Tips & Tricks

Published on February 9, 2015 by Shane Bryson . Revised on July 23, 2023 by Shona McCombes.

This example guides you through the structure of an essay. It shows how to build an effective introduction , focused paragraphs , clear transitions between ideas, and a strong conclusion .

Each paragraph addresses a single central point, introduced by a topic sentence , and each point is directly related to the thesis statement .

As you read, hover over the highlighted parts to learn what they do and why they work.

Instantly correct all language mistakes in your text

Upload your document to correct all your mistakes in minutes

Table of contents

Other interesting articles, frequently asked questions about writing an essay, an appeal to the senses: the development of the braille system in nineteenth-century france.

The invention of Braille was a major turning point in the history of disability. The writing system of raised dots used by visually impaired people was developed by Louis Braille in nineteenth-century France. In a society that did not value disabled people in general, blindness was particularly stigmatized, and lack of access to reading and writing was a significant barrier to social participation. The idea of tactile reading was not entirely new, but existing methods based on sighted systems were difficult to learn and use. As the first writing system designed for blind people’s needs, Braille was a groundbreaking new accessibility tool. It not only provided practical benefits, but also helped change the cultural status of blindness. This essay begins by discussing the situation of blind people in nineteenth-century Europe. It then describes the invention of Braille and the gradual process of its acceptance within blind education. Subsequently, it explores the wide-ranging effects of this invention on blind people’s social and cultural lives.

Lack of access to reading and writing put blind people at a serious disadvantage in nineteenth-century society. Text was one of the primary methods through which people engaged with culture, communicated with others, and accessed information; without a well-developed reading system that did not rely on sight, blind people were excluded from social participation (Weygand, 2009). While disabled people in general suffered from discrimination, blindness was widely viewed as the worst disability, and it was commonly believed that blind people were incapable of pursuing a profession or improving themselves through culture (Weygand, 2009). This demonstrates the importance of reading and writing to social status at the time: without access to text, it was considered impossible to fully participate in society. Blind people were excluded from the sighted world, but also entirely dependent on sighted people for information and education.

In France, debates about how to deal with disability led to the adoption of different strategies over time. While people with temporary difficulties were able to access public welfare, the most common response to people with long-term disabilities, such as hearing or vision loss, was to group them together in institutions (Tombs, 1996). At first, a joint institute for the blind and deaf was created, and although the partnership was motivated more by financial considerations than by the well-being of the residents, the institute aimed to help people develop skills valuable to society (Weygand, 2009). Eventually blind institutions were separated from deaf institutions, and the focus shifted towards education of the blind, as was the case for the Royal Institute for Blind Youth, which Louis Braille attended (Jimenez et al, 2009). The growing acknowledgement of the uniqueness of different disabilities led to more targeted education strategies, fostering an environment in which the benefits of a specifically blind education could be more widely recognized.

Several different systems of tactile reading can be seen as forerunners to the method Louis Braille developed, but these systems were all developed based on the sighted system. The Royal Institute for Blind Youth in Paris taught the students to read embossed roman letters, a method created by the school’s founder, Valentin Hauy (Jimenez et al., 2009). Reading this way proved to be a rather arduous task, as the letters were difficult to distinguish by touch. The embossed letter method was based on the reading system of sighted people, with minimal adaptation for those with vision loss. As a result, this method did not gain significant success among blind students.

Louis Braille was bound to be influenced by his school’s founder, but the most influential pre-Braille tactile reading system was Charles Barbier’s night writing. A soldier in Napoleon’s army, Barbier developed a system in 1819 that used 12 dots with a five line musical staff (Kersten, 1997). His intention was to develop a system that would allow the military to communicate at night without the need for light (Herron, 2009). The code developed by Barbier was phonetic (Jimenez et al., 2009); in other words, the code was designed for sighted people and was based on the sounds of words, not on an actual alphabet. Barbier discovered that variants of raised dots within a square were the easiest method of reading by touch (Jimenez et al., 2009). This system proved effective for the transmission of short messages between military personnel, but the symbols were too large for the fingertip, greatly reducing the speed at which a message could be read (Herron, 2009). For this reason, it was unsuitable for daily use and was not widely adopted in the blind community.

Nevertheless, Barbier’s military dot system was more efficient than Hauy’s embossed letters, and it provided the framework within which Louis Braille developed his method. Barbier’s system, with its dashes and dots, could form over 4000 combinations (Jimenez et al., 2009). Compared to the 26 letters of the Latin alphabet, this was an absurdly high number. Braille kept the raised dot form, but developed a more manageable system that would reflect the sighted alphabet. He replaced Barbier’s dashes and dots with just six dots in a rectangular configuration (Jimenez et al., 2009). The result was that the blind population in France had a tactile reading system using dots (like Barbier’s) that was based on the structure of the sighted alphabet (like Hauy’s); crucially, this system was the first developed specifically for the purposes of the blind.

While the Braille system gained immediate popularity with the blind students at the Institute in Paris, it had to gain acceptance among the sighted before its adoption throughout France. This support was necessary because sighted teachers and leaders had ultimate control over the propagation of Braille resources. Many of the teachers at the Royal Institute for Blind Youth resisted learning Braille’s system because they found the tactile method of reading difficult to learn (Bullock & Galst, 2009). This resistance was symptomatic of the prevalent attitude that the blind population had to adapt to the sighted world rather than develop their own tools and methods. Over time, however, with the increasing impetus to make social contribution possible for all, teachers began to appreciate the usefulness of Braille’s system (Bullock & Galst, 2009), realizing that access to reading could help improve the productivity and integration of people with vision loss. It took approximately 30 years, but the French government eventually approved the Braille system, and it was established throughout the country (Bullock & Galst, 2009).

Although Blind people remained marginalized throughout the nineteenth century, the Braille system granted them growing opportunities for social participation. Most obviously, Braille allowed people with vision loss to read the same alphabet used by sighted people (Bullock & Galst, 2009), allowing them to participate in certain cultural experiences previously unavailable to them. Written works, such as books and poetry, had previously been inaccessible to the blind population without the aid of a reader, limiting their autonomy. As books began to be distributed in Braille, this barrier was reduced, enabling people with vision loss to access information autonomously. The closing of the gap between the abilities of blind and the sighted contributed to a gradual shift in blind people’s status, lessening the cultural perception of the blind as essentially different and facilitating greater social integration.

The Braille system also had important cultural effects beyond the sphere of written culture. Its invention later led to the development of a music notation system for the blind, although Louis Braille did not develop this system himself (Jimenez, et al., 2009). This development helped remove a cultural obstacle that had been introduced by the popularization of written musical notation in the early 1500s. While music had previously been an arena in which the blind could participate on equal footing, the transition from memory-based performance to notation-based performance meant that blind musicians were no longer able to compete with sighted musicians (Kersten, 1997). As a result, a tactile musical notation system became necessary for professional equality between blind and sighted musicians (Kersten, 1997).

Braille paved the way for dramatic cultural changes in the way blind people were treated and the opportunities available to them. Louis Braille’s innovation was to reimagine existing reading systems from a blind perspective, and the success of this invention required sighted teachers to adapt to their students’ reality instead of the other way around. In this sense, Braille helped drive broader social changes in the status of blindness. New accessibility tools provide practical advantages to those who need them, but they can also change the perspectives and attitudes of those who do not.

Bullock, J. D., & Galst, J. M. (2009). The Story of Louis Braille. Archives of Ophthalmology , 127(11), 1532. https://​doi.org/10.1001/​archophthalmol.2009.286.

Herron, M. (2009, May 6). Blind visionary. Retrieved from https://​eandt.theiet.org/​content/​articles/2009/05/​blind-visionary/.

Jiménez, J., Olea, J., Torres, J., Alonso, I., Harder, D., & Fischer, K. (2009). Biography of Louis Braille and Invention of the Braille Alphabet. Survey of Ophthalmology , 54(1), 142–149. https://​doi.org/10.1016/​j.survophthal.2008.10.006.

Kersten, F.G. (1997). The history and development of Braille music methodology. The Bulletin of Historical Research in Music Education , 18(2). Retrieved from https://​www.jstor.org/​stable/40214926.

Mellor, C.M. (2006). Louis Braille: A touch of genius . Boston: National Braille Press.

Tombs, R. (1996). France: 1814-1914 . London: Pearson Education Ltd.

Weygand, Z. (2009). The blind in French society from the Middle Ages to the century of Louis Braille . Stanford: Stanford University Press.

If you want to know more about AI tools , college essays , or fallacies make sure to check out some of our other articles with explanations and examples or go directly to our tools!

• Ad hominem fallacy
• Post hoc fallacy
• Appeal to authority fallacy
• False cause fallacy
• Sunk cost fallacy

College essays

• Choosing Essay Topic
• Write a College Essay
• Write a Diversity Essay
• College Essay Format & Structure
• Comparing and Contrasting in an Essay

 (AI) Tools

• Grammar Checker
• Paraphrasing Tool
• Text Summarizer
• AI Detector
• Plagiarism Checker
• Citation Generator

Here's why students love Scribbr's proofreading services

Discover proofreading & editing

An essay is a focused piece of writing that explains, argues, describes, or narrates.

In high school, you may have to write many different types of essays to develop your writing skills.

Academic essays at college level are usually argumentative : you develop a clear thesis about your topic and make a case for your position using evidence, analysis and interpretation.

The structure of an essay is divided into an introduction that presents your topic and thesis statement , a body containing your in-depth analysis and arguments, and a conclusion wrapping up your ideas.

The structure of the body is flexible, but you should always spend some time thinking about how you can organize your essay to best serve your ideas.

Your essay introduction should include three main things, in this order:

• An opening hook to catch the reader’s attention.
• Relevant background information that the reader needs to know.
• A thesis statement that presents your main point or argument.

The length of each part depends on the length and complexity of your essay .

A thesis statement is a sentence that sums up the central point of your paper or essay . Everything else you write should relate to this key idea.

A topic sentence is a sentence that expresses the main point of a paragraph . Everything else in the paragraph should relate to the topic sentence.

At college level, you must properly cite your sources in all essays , research papers , and other academic texts (except exams and in-class exercises).

Add a citation whenever you quote , paraphrase , or summarize information or ideas from a source. You should also give full source details in a bibliography or reference list at the end of your text.

The exact format of your citations depends on which citation style you are instructed to use. The most common styles are APA , MLA , and Chicago .

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the “Cite this Scribbr article” button to automatically add the citation to our free Citation Generator.

Bryson, S. (2023, July 23). Example of a Great Essay | Explanations, Tips & Tricks. Scribbr. Retrieved September 9, 2024, from https://www.scribbr.com/academic-essay/example-essay-structure/

Is this article helpful?

Shane Bryson

Shane finished his master's degree in English literature in 2013 and has been working as a writing tutor and editor since 2009. He began proofreading and editing essays with Scribbr in early summer, 2014.

Other students also liked

How to write an essay introduction | 4 steps & examples, academic paragraph structure | step-by-step guide & examples, how to write topic sentences | 4 steps, examples & purpose, what is your plagiarism score.