What is the Structure of a cell

Structure of a cell by entiregrade
Structure of a cell by entiregrade

A cell is a basic functional and structural unit of life.
It forms the body of a living organism.

The composition of animal cells makes the body of an animal and also the composition of plant cells make a body of plants.

The diagram of plant and animal cell shows some
differences but there are many similarities between them.

Structure of cell shows that a cell has mainly three parts these are as follows,

A. Cell membrane and cell wall

B. Cytoplasm


A. Cell membrane and cell wall

The cell membrane is very thin and elastic.

It represents the outermost layer of the cell.

It encloses protoplasm of the cell.

In a plant cell, cell membrane lies inner to the cell wall and it protects the cell.

The cell membrane allows suitable materials into the cell from outside.

Plant cells have additional layers outside the cell membrane called a cell wall.

In an animal cell, there is no cell wall.

The cell wall is a non-living and rigid layer which determines the fixed shape of a plant cell.

The cell wall protects the plant cell from injury.

Due to the presence of the cell wall, we can easily distinguish plant cell from an animal cell.

B. Cytoplasm

The cytoplasm is a part of protoplasm.

Protoplasm is a living substance and it consists of nucleoplasm and cytoplasm.

The cytoplasm consists of different organelles like centrosome, vacuole, mitochondria and plastids.

a. Centrosome

It is present in animal cells only and it is single in number.

It has two dot-like structures surrounded by tubules.

It is very important for cell division.

b. Vacuole

It is present in animal cells and plant cells both.

It is bigger in plant cells and smaller in animal cells.

It is made up of thin tonoplast layer, which surrounds water and water-soluble substances.

The vacuole is the storehouse of a cell because it concerns the storage of food and excretion.

c. Mitochondria

The rod-like granular structures present in animal and plant cells both (singular mitochondrion) are mitochondria.

Mitochondria help in respiration and produce energy, which is stored in special molecules, So they are considered as a powerhouse of a cell.

d. Plastids

Plastids are only present in plant cells.

On the basis of structure, function and pigments,
plastids are of three types.
They are chloroplast, chromoplast and leucoplast.

The chloroplast is present in the green parts such as leaves of a plant due to the presence of chlorophyll pigment.

It helps in photosynthesis, So it is the kitchen of a cell.

Chromoplast is present in flowers and fruits, and it gives attractive colours to them.

Chromoplast also helps in pollination and dispersal of seeds.

Leucoplast is present in the colourless part of plants like roots.

Leucoplast stores food for the plant in the form of protein, carbohydrates and fats.

e. Ribosomes

They are membrane-less cell organelles.

They are either attached to the membrane of the endoplasmic reticulum or in the cytoplasm.

They are also known as protein factories of cells because they help in protein synthesis.

f. Endoplasmic reticulum

It is a network membrane found throughout the cell.

It gives support to the cell and acts as a manufacturing and packaging system.

g. Golgi complex

They are flattened networks of sac-like structures present in the cytoplasm of the cell.

Golgi complex help in the secretion of various chemical substances.

h. Lysosomes

Lysosomes contain a variety of enzymes.

They are formed from the vesicles produced by the endoplasmic reticulum and Golgi complex.

They help in digesting food, non-functional old and worn-out cells and bacteria after infection.

They also breakdown the cell when it dies.

Lysosomes are also known as suicidal bags of the cell.
This is because of the breakdown of complex molecules and pieces of cells and leads to the death of the cell.

C. Nucleus

The mass of the nuclear membrane, nucleoplasm, nucleolus and chromatin fibres together form a nucleus.

The nucleus is located somewhere in the middle of the cell.

In animal cells, the nucleus is spherical in shape, but in a plant cell, it often becomes flattened.

The nucleoplasm is a liquid substance in which nucleolus and chromatin fibres are present.

The nucleolus may be one in number and did not bound.

Chromatin fibres are very fine thread-like structures.

The nucleus functions as the brain of the cell because it controls all the activities of the cell.

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