What is a cell called?

Definition of Cell:

The cell is the structural and functional unit of the body of living organisms and often has the ability to reproduce itself. It is that smallest organized form of various substances in which all those activities take place which collectively we call life. It was discovered by Robert Hooke in 1665 AD. Organisms with a single cell, such as bacteria, protozoa and yeasts, etc., are called unicellular organisms and complex organisms with more than one cell are called multicellular organisms.

Cell Types:

There are two types of cells:

  1. Prokaryotic cell
  2. Eukaryotic cell

1. Prokaryotic Cells

Prokaryotic or pronucleated cells are found in organisms whose cells do not have a membrane-enclosed nucleus. It was the first form of life on earth.

Following are the characteristics of prokaryotic organisms:

  1. Undeveloped and primitive cells are found in these organisms.
  2. Their size is small.
  3. The nucleus is not found.
  4. The nucleus is also not found.
  5. Only one chromosome is found.
  6. Cell organelles are also not found surrounded by cell wall.
  7. Cell division occurs by mitotic division.
  8. Cyanobacteria such as bacteria and blue-green algae are examples of prokaryotic organisms.

2. Eukaryotic Cell

Eukaryote or eukaryote is called all those organisms whose cells (cell) have a nucleus surrounded by nuclear art.

Following are the characteristics of eukaryotic organisms:

  1. Developed and new cells are found in them.
  2. Their size is big.
  3. The nucleus is found.
  4. Nuclear matter is also found.
  5. More than one chromosome is found.
  6. Cell organelles are also found surrounded by cell wall.
  7. Cell division occurs by mitosis and meiosis.

Subcellular component

All cells, whether prokaryotic or eukaryotic, have a membrane that covers, and controls, the cell. So that there is no damage to the cell. Subcellular components of DNA, Genes and RNA are found inside all cells:-

  • Cell membrane
  • Cytoskeleton
  • Genetic material
  • Organelles

Cell membrane

The cell membrane is a semi-permeable living membrane that surrounds the cytoplasm of each living cell. The cell membrane is made up of three layers, out of which the outer and inner layers are made by proteins and the middle layer is made up of lipids or fats. It forms the shape of the cell and protects the organism.

Cell skeleton

The proteinaceous reticulum filament found in the cytoplasm is called the cell skeleton (cytoskeleton). Its function is to provide mechanical support to the cell, to maintain motion, shape.

Genetic material

There are two different types of genetic material:-

  • DNA - Deoxyribonucleic acid
  • RNA - Ribose Nucleic Acid

RNA-Ribose Nucleic Acid
was discovered by Friedrich Mischer. RNA is used to transport information. Molecules are used to link amino acids during protein translation. DNA-Deoxyribo Nucleic Acid was discovered by English scientists James Watson and Francis Crick. Cells use DNA for their long-term information storage.


Just as different parts of the body perform different functions, similarly the structures inside the cell perform specific functions. Hence these structures are called cell organelles. For example, the mitochondria or nematode is called the 'powerhouse' of the cell because most of the chemical energy of the cell is produced in it. There are many types of organelles in a cell. Apart from this, all the substances inside the cell membrane except the nucleus in the cell are called cytoplasm. Therefore we can say that the major cell organelles located inside the cytoplasm are:-

  1. Nucleolus
  2. Cell Nucleus
  3. Ribosome
  4. Vesicle
  5. Endoplasmic reticulum
  6. Golgi apparatus
  7. Cytoskeleton
  8. Mitochondrion
  9. Vacuole
  10. Cytosol
  11. Lysosome
  12. Centriole

1. Nucleus: The nucleus is the largest dense structure located in the nucleus within the cell nucleus of the cells of plants, animals and eukaryotic organisms. It is made up of proteins, DNA and RNA.

2. Cell Nucleus: The nucleus or cell nucleus is a part (or cytoplasm) enclosed by a membrane in most cells of plants, animals and eukaryotic organisms. The fibers of genetic material are organized into chromosomes (chromosomes) using several proteins. The genes present in these chromosomes are the genome of the cell and govern the processes of the cell. The nucleus stores these genes and drives the gene behavior.

3. Ribosomes: Ribosomes are very fine particles located in the cytoplasm of a living cell, which play an important role in the synthesis of proteins. They convert signals from genetic material (DNA or RNA) into protein chains. Ribosomes were discovered by Romanian biologist Jorge Peled in the 1955s.

4. Intent: Intent is naturally formed during the processes of secretion, uptake and transport of material within the plasma membrane.

5. Rough endoplasmic reticulum or endoplasmic reticulum: Endoplasmic reticulum is a membranous organelle located in eukaryotic cells. Its membrane originates from the membrane of the nucleus. It looks like a long tube or round or rectangular bags. The endoplasmic reticulum is mainly the transport system of eukaryotic cells. Apart from this, it also has many other important functions, such as protein folding.

6. Golgi apparatus: Some sac-like organelles are found near the nucleus in the cytoplasm of the cell, these are called Golgi bodies or Golgi bodies or Golgi apparatus. Camillo Golgi was an Italian neuroscientist who detected it in the neuroblasts of the white owl, which is known by its name.

7. Cytoplasm: The proteinaceous reticulum filament found in the cytoplasm is called the cell skeleton (cytoskeleton). Its function is to provide mechanical support to the cell, to maintain motion, shape. 

8. Mitochondria: Irregularly scattered double membrane bonded cell organelles in the cytoplasm of all living plant and animal cells except bacteria and blue green algae are called mitocytes or mitochondria. They appear round, elongated or elliptical when viewed with the help of a microscope inside the cell.

9. Vacuole: A vacuole is a structure found in the cytoplasm of animal and plant cells. Those non-living cellular structures without cytoplasm which are filled with water-like fluid and surrounded by a covering called tonoplast are called vacuoles. Food items are stored in them. The vacuoles of aquatic plants become gaseous and help the plants to swim.

10. Cytoplasm or cytoplasm: The whole substance inside the cell membrane except the nucleus is called cytoplasm. It is found in all cells and resides inside the cell membrane and outside the nuclear membrane. It is a fibrous, jelly-like, semi-liquid substance. It is transparent and sticky. It makes up 70% of the cell. It is composed of water and organic and inorganic solids.

11. Lymphocyte: The organelles that are covered in the cytoplasm of the animal cell are called lysosomes. It helps in intracellular digestion. Christian de Duve first discovered lysosomes in 1958.

12. Asterisk: In cell biology, the centromere is a cylindrical organelle mainly composed of a protein called tubulin. A star center is present in most eukaryotic cells.

Now practice related questions and see what you learnt?

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Cell: Structure and Function FAQs:

Lymphocytes are a type of white blood cell found in our lymph system. These blood cells are associated with the body's blood system and play an important role in cleaning the blood, strengthening the immune system, and helping fight diseases.

There is no division in the nervous tissue in humans. Nerve cells or Neuron transmit information from sensory organs in the form of electrochemical impulses.

The human body is made up of cells and these cells contain chromosomes. A normal human has 46 chromosomes. Chromosomes are considered to be the carriers of the genetic properties of human beings.

Some prokaryotes, such as cyanobacteria, have membrane-bound extensions in their cytoplasm called chromoplasts. Bacterial cells are motile or non-motile. If they are mobile then thin structures like cell wall are found in them.

Lymph cells play an important role among the blood cells, and their main function is to operate the body's immune system. These cells perform functions related to immunity and assist in the defense against microbes, viruses, or other pathogens present in the blood.

  Last update :  Tue 13 Sep 2022
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