Diagram of cell structure and function

 Diagram of cell structure and function


A simple diagram of cell
A simple diagram of a cell

In Latin cell means ‘small room’. In Biology, the cell is the basic unit of all living organisms. Cells are the smallest independent component of our body that’s why it is often called a building block of life. In this article, we are going to discuss the structure, function, and detailed diagram of a cell. 



Contents


1  Definition of cell


2  Discovery of cell 


3 Structure of Cell 


4  Function of Cell


5  Types of Cell


6   Cell Division and cell cycle




What is a cell?

The cell is the basic structural, functional, and biological unit of organisms. The size of cells is approximately 0.0001 mm to nearly 150 mm. The study of cells is referred to as cell Biology or cytology. 

Let's see a simple diagram of a cell



Definition of Cell 

“Cell is defined as the structural, functional, and biological unit of living organisms. It is an autonomous self-replicating unit that may exist as a functional independent unit of life, or as a sub-unit in a multicellular organism that performs a particular function in tissues and organs.


Discovery of cell

In 1665 Robert Hooke discovered the cell. Robert Hook observed a piece of a bottle cork under a low magnification compound microscope and noticed some structure similar which remind him of small rooms inherited by monks so he named the structure a cell. He thought-cells as nonliving.


In 1674 Anton van Leeuwenhoek discovered that cell is living organisms. 

Later in 1883, Robert Brown gave the first insight of cell structure. 



Structure of  cell

Cell consist of  three parts

I. Cell Membrane 

II. Nucleus 

III. Cytoplasm


The cytoplasm consists of various cell organelles. 



Diagram of cell structure
Diagram of cell structure




Function of cell

A cell is the building block of life. The main functions of cells are- 


1. Cell provide structure and support of body 

2. Cell helps in growth through mitosis, 

3. Cell helps passive and active transport in the body, 

4. Cell Produce energy of organisms.

5. Cell creates metabolic reactions and helps the body to absorb food

6. Cell takes part in reproduction


Types of cell


Based on the structure of cell there are two types of cells 

  1. Prokaryotic cell 

  2. Eukaryotic cell


Prokaryotic cells-

Prokaryotic cells are simple cells without a nucleus and membrane-bound cellular organelles. 


Characters of Prokaryotic cells -

  1. Prokaryotic cells do not have a nucleus. Genetic materials are present in a small part of the cytoplasm and this is called a nucleoid. 
  2. The size of prokaryotic cells is approximately from 0.1 to 0.5 µm in diameter.
  3. Genetic materials are either DNA or RNA. 
  4. Prokaryotes generally reproduce by binary fission
  5. Prokaryotic cells don’t reproduce sexually. 

Example of prokaryotic cell- Bacteria 


Structure of Prokaryotic cell 

A Prokaryotic cell contains 5 major parts -

I. Plasma membrane-  it is a thin lipid bilayer that keeps cell contains separate from outer environments. 

II. Cell wall - it is a protective layer that gives shape and rigidity to cells. In some cases, the cell wall is enclosed by another thick layer made of sugar it is called a ‘capsule’. 

III. Cytoplasm- it is a jelly-like substance that contains nucleoid and other cellular components. 

IV. DNA or RNA- it varies the genetic materials. They have sigle chromosome. 

V. Ribosomes - it synthesizes protein. 

Some prokaryotic cells contain a long whip-like structure called flagella which helps in locomotion.



Diagram of prokaryotic cell
Diagram of prokaryotic cell



Eukaryotic cells-

Prokaryotic cells are found in all multicellular organisms. They have membrane-bound organisms such as mitochondria, Golgi body, etc., and a proper nucleus with chromosomes. 


For example- all multicellular organisms such as humans, dogs, cows, plants, etc have eucaryotic cells. 


Characters of Eukaryotic cells -

  1. Eucaryotic cells contain a proper nucleus bound by a nuclear membrane. 
  2. The approximate size of Eucaryotic cells varies from 10–100 µm in diameter
  3. Eukaryotic cells reproduce sexually snd asexually. 
  4. Eukaryotic cells contain membrane-bound cell organelles. 
  5. The locomotory organ of Eukaryotic cells is Flagella and cilia. 

Types of eukaryotic cell

There are 4 types of Eukaryotic cells 

  1. Plant Cells 

  2. Animal Cells 

  3. Fungal cells 

  4. Protozoa cells 


Diagram of Eukaryotic cell
Diagram of Eukaryotic cell



Structure of Eukaryotic Cells 


  1. Cell wall - it is a protective layer made of cellulose microfibrils and a network of glycans embedded in the matrix of pectin polysaccharides that surrounds the outside of the cell membrane.  It is rigid and stiff in structure. 

The cell wall provides shape and support to the cells. It also protects cells from mechanical shocks and injuries. 

The cell wall is present in some eukaryotic cells such as Plant cells, a fungal cell, etc. 


diagram of a cell wall
Diagram of a cell wall



  1. Cell Membrane - the next layer inside the cell wall is the cell membrane. The structure of a cell membrane and functions are similar in prokaryotic and eukaryotic cells. 

 The cell membrane is also called a plasma membrane. It is made up of a phospholipid bilayer.  Integral proteins are embedded between the two layers. 

The cell membrane controls the movement of cellular substances inside and outside of the cell. it is a porous membrane that controls the cellular transmission. 

Cell Membrane works as a cell wall for those who lack a cell wall. 


diagram of a cell membrane
diagram of a cell membrane



  1. Cytoplasm - It is a fluid-filled space that accommodates all internal cell organelles and other molecules. It is a jelly-like substance. It is a  cytosol and a water-soluble solution containing minerals, ions, and other molecules. 

  1. Endoplasmic Reticulum- Endoplasmic reticulum is a ribosome containing a network of small, tubular structures. It divides the cell surface into two parts. 

There are 2 types of endoplasmic reticulum rough and smooth.

 

  1. Nucleus - Nucleus is a double membrane cell organelles present in the cytoplasm. It contains the genetic information of cells. That’s why it is called the brain of the cell. 

Nucleus contains -

  1. Nuclear envelope- it is the outmost layer of the nucleus. It is a double membrane structure. The outer layer is the endoplasmic reticulum and the inner one is the nuclear pores. 
  2. Nucleoplasm –the fluid of the nucleus which contains chromosome and nucleolus. 
  3. Nucleolus – this is a protein containing membrane-less part of a nucleus that synthesizes RNA. 
  4. Chromatin – it is the part of the nucleus which is organized in the nucleoplasm and contains DNA and histone protein. 


diagram of a cell nucleus
Diagram of a cell nucleus

diagram of a cell nucleus
Diagram of a cell nucleus



  1. Cell Organelles- there are lots of membrane-bound cell organelles present in the eukaryotic cell which perform various functions of a cell. 

Few cell organelles are -


i. Mitochondria- it produces energy and called as ‘powerhouse of the cell.’ it helps in metabolism. 

ii. Golgi Apparatus-  it helps in the formation of glycoproteins and glycolipids.

iii. Ribosomes- it synthesizes protein. 

iv. Lysosomes- it possesses hydrolytic enzymes which help in the digestion of protein, lipids, carbohydrates. It is also called a suicidal bag as it can digest important substances also. 


Plant cells 

Plant cells are eukaryotic cells with some distinct organelles. Pleasance of a cell wall is a specific feature of a plant cell. 


Structure of plant cell

  1. Plant cells are larger than animal cells. They are generally square in shape. 
  2. Plant cells contain a rigid and prominent cell wall that is composed of cellulose, glycoproteins, lignin, pectin and hemicellulose. 
  3. Inside cell wall plant cell contains cell membrane which regulates the fluid transmission in the cell. 
  4. It contains a nucleus and nucleopore. 
  5. Plastid is one of the most important cell organelles of a plant cell. It helps in the photosynthesis and storing of starch. Green plastid is called as chloroplast and other color plastids are known as Leucoplasts. 
  6. The plant cell contains a big vacuole which is called a Central Vacuole. 
  7. Plan cell also contains other cellular organelles present in eukaryotic cells. 

Diagram of plant cell
Diagram of plant cell



Animal cell 

Animal cells are Eukaryotic cells that lack a cell wall and present in the body of animals. 


Structure of animal cell 

  1. Animal cells contain cell membranes. The primary function of the cell membrane is to provide shape and protection to cells. 
  2. It contains a prominent nuclear membrane that surrounds the nucleus. 
  3. It contains a proper membrane-bound nucleus. 
  4. There is a small organelle found in an animal cell near the nucleus. It is called a Centrosome.
  5. Animal cells contain other essential cellular organelles of eukaryotic cells. 

Let's have a look at the labeled diagram of an animal cell to understand it better. 


Diagram of animal cell
Diagram of animal cell



Human cell -

Human cells are actually animal cells i.e. Eukaryotic cells with a proper nucleus and membrane-bound cell organelles. 

There are various types of cells present in the human body. They are -

Blood cells

Skin cells or epidermal cells

Nerve cells or Neurons

Stem cells

Muscle cells

Bone cells

Fat cells etc. 


We will discuss some of these cells in detail later. 


Diagram of human cell
Diagram of human cell




Cell division and cell cycle-

It is the process by which parent cells divide themselves into two or more daughter cells. 

 Cell division is generally two types - Mitosis and Miosis. 


During the cell division of Eukaryotic cells, a series of events that take place are called as cell cycle or cell division cycle. 


We will discuss detailed cell division and cell cycle in some other articles.  



In this article, we discussed the definition, types, structure, and diagram of cells. If there is any question please drop us a mail. 


Stay tuned for other topics. 


Thanks and regards 

Diagram of Team.