Chapter 1: Fundamental Unit of Life
Introduction
The cell is the fundamental unit of life. It is the basic structural and functional unit of all
living organisms. All living organisms are made up of cells. Some organisms are unicellular
(made of a single cell), while others are multicellular (made of many cells).
Discovery of the Cell
The discovery of the cell was made by Robert Hooke in 1665 when he observed a slice of
cork under a microscope. He saw small box-like structures, which he called 'cells.'
Types of Cells
Cells can be classified into two types:
1. Prokaryotic Cells: These cells do not have a well-defined nucleus. The genetic material is
present in a region called the nucleoid. Example: Bacteria.
2. Eukaryotic Cells: These cells have a well-defined nucleus and other membrane-bound
organelles. Example: Plant and animal cells.
Structure of the Cell
A cell has three main parts:
1. Cell Membrane: It is the outer covering of the cell that controls the movement of
substances in and out of the cell.
2. Cytoplasm: It is the jelly-like substance present inside the cell membrane where various
cell organelles are found.
3. Nucleus: It is the control center of the cell that contains the genetic material (DNA).
Cell Organelles
1. Mitochondria: Known as the powerhouse of the cell, mitochondria produce energy in the
form of ATP through cellular respiration.
2. Endoplasmic Reticulum (ER): It is a network of membranes involved in the synthesis and
transport of proteins and lipids. Rough ER has ribosomes on its surface, while Smooth ER
does not.
Introduction
The cell is the fundamental unit of life. It is the basic structural and functional unit of all
living organisms. All living organisms are made up of cells. Some organisms are unicellular
(made of a single cell), while others are multicellular (made of many cells).
Discovery of the Cell
The discovery of the cell was made by Robert Hooke in 1665 when he observed a slice of
cork under a microscope. He saw small box-like structures, which he called 'cells.'
Types of Cells
Cells can be classified into two types:
1. Prokaryotic Cells: These cells do not have a well-defined nucleus. The genetic material is
present in a region called the nucleoid. Example: Bacteria.
2. Eukaryotic Cells: These cells have a well-defined nucleus and other membrane-bound
organelles. Example: Plant and animal cells.
Structure of the Cell
A cell has three main parts:
1. Cell Membrane: It is the outer covering of the cell that controls the movement of
substances in and out of the cell.
2. Cytoplasm: It is the jelly-like substance present inside the cell membrane where various
cell organelles are found.
3. Nucleus: It is the control center of the cell that contains the genetic material (DNA).
Cell Organelles
1. Mitochondria: Known as the powerhouse of the cell, mitochondria produce energy in the
form of ATP through cellular respiration.
2. Endoplasmic Reticulum (ER): It is a network of membranes involved in the synthesis and
transport of proteins and lipids. Rough ER has ribosomes on its surface, while Smooth ER
does not.
