The Fundamental Unit of Life

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What is a Cell?

The smallest structural and functional unit/building block of a living organism is known as a cell. It is membrane-bound and consists of cytoplasm, genetic material, organelles and other components. Cells also contain nucleic acids, proteins, carbohydrates, and lipids.

A collection of cells performing certain functions is called a tissue. Bodily functions are regulated by tissues and organs. On the whole, the entire process of cell development and tissue development is interrelated.

Types of Cell

A plant has a variety of cells including root cells, stem cells, and leaf cells. The functions of human cells are multifarious as well, they have distinct functions to perform.

Cell Structure

Prokaryotic and eukaryotic cells are pretty much similar in structure. Their structural resemblance includes the presence of plasma membrane, cytoplasm, and ribosomes in them.

Cell Theory

We all know that living organisms are made up of cells. As per the cell theory, cells come from pre-existing cells. They are the structural unit of all living organisms. Cells are the ‘basic unit of reproduction’ as well.

Discovery of Cell

Cell was discovered by Robert Hooke in 1665. He observed them while viewing a slice of bottle cork under a microscope. “Cell” means a “small room” in Latina. However, it was the observations of Anton Van Leewenhoek which proved that cells were living organisms.


A cell is made up of organelles. Mitochondria, being the most important organelle, is responsible for transporting energy to the cell. It is called the powerhouse of the cell. The endoplasmic reticulum functions as an active transporting system.

The ‘packaging system’ of the cell is called golgi apparatus. Lysosomes are the digestive enzymes and ribosomes are responsible for synthesizing proteins for the cells. The organelles are protected by a jelly-like substance known as the cytoplasm.

Cell Organelles and Their Functions

They are the multiple subunits of the cell. Cell organelles have their own distinct characteristics and specific functions to perform as well.    

Plasma Membrane

Plasma membrane functions as a protective layer. It also monitors the movement of substances which come in and out of the cell.


Ribosomes supply protein to the cells by making use of RNA and amino acids.


Being the powerhouse of the cell, mitochondria is an active respiratory agent.


Vacuoles remove the waste products from the cell. They maintain the pH balance of the cell as well. 


Cytoskeleton is responsible for maintaining the shape and elasticity of the cells. They also anchor the nucleus.


  • Being the main site for ‘photosynthesis’, chloroplasts are responsible for producing food.
  • Chromoplasts protect chlorophyll in plants, they absorb light energy as well.
  • The necessary nutrients of an expired cell are protected by gerontoplasts. 
  • Leucoplasts act as storage agents for lipids, proteins and starch.

Endoplasmic Reticulum

It is divided into smooth endoplasmic reticulum and rough endoplasmic reticulum. Functions of smooth endoplasmic reticulum comprise producing enzymes in the liver, transporting vesicles, synthesizing hormones in the brain cell and contracting muscle cells. Meanwhile, the functions of rough endoplasmic reticulum include supplying proteins, producing insulin and antibodies.  

Golgi Apparatus

Manufacturing, transporting, and storing products from the endoplasmic reticulum is the primary responsibility of golgi apparatus. 


  • A cell is the fundamental unit of human life.
  • Robert Hooke discovered cells.
  • Different organelles of a cell perform different functions.
  • Cells are structured by cytoplasm, plasma membrane and ribosomes.
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