Cell: the unit of life
Definition: - Cell is the fundamental, Structural and
functional unit of all living beings.
Every cell has its own life. Old and weak cells in the
body continuously die and replace by new one.
RBC die after 120 days.
Most organism including ourselves, start life as
single cell called zygote.
Invention of Microscope
First Microscope: - Antony van Leeuwenhoek
(Dutch scientist)
Compound microscope and discover cell: - Robert
Hooke
Cell Theory
Cell theory given by Matthias Schleiden, Theodor
Schwann and Rudolf Virchow.
Cell theory: -
1. The cell is the smallest unit of structure of all living
things.
2. The cell is the unit of function of all living things.
3. All cells arise from pre- existing cells.
, Cell – How many and small
Greater the organism, greater is the no. of cell in
body.
Single Celled – Made up of one single cell.
Example: - Bacteria and yeast
Few Celled - Made up of a few hundred or few
thousand cells.
Example: - Spirogyra and Volvox.
Multi-celled - Made up of millions and billions of
cells.
Example: - Human beings and mango tree.
Smallest Cell - Bacteria and RBC cells.
Longest Cell – Nerve cells.
Largest Cells – Ostrich egg.
Structure of a cell.
Most parts of a cell have a definite shape, structure
and function called Cell Organelles.
1. Cell wall (only in plant cell): -
Main characteristics Chief Function
Outermost in plant Gives rigidity and
cell. shape
Definition: - Cell is the fundamental, Structural and
functional unit of all living beings.
Every cell has its own life. Old and weak cells in the
body continuously die and replace by new one.
RBC die after 120 days.
Most organism including ourselves, start life as
single cell called zygote.
Invention of Microscope
First Microscope: - Antony van Leeuwenhoek
(Dutch scientist)
Compound microscope and discover cell: - Robert
Hooke
Cell Theory
Cell theory given by Matthias Schleiden, Theodor
Schwann and Rudolf Virchow.
Cell theory: -
1. The cell is the smallest unit of structure of all living
things.
2. The cell is the unit of function of all living things.
3. All cells arise from pre- existing cells.
, Cell – How many and small
Greater the organism, greater is the no. of cell in
body.
Single Celled – Made up of one single cell.
Example: - Bacteria and yeast
Few Celled - Made up of a few hundred or few
thousand cells.
Example: - Spirogyra and Volvox.
Multi-celled - Made up of millions and billions of
cells.
Example: - Human beings and mango tree.
Smallest Cell - Bacteria and RBC cells.
Longest Cell – Nerve cells.
Largest Cells – Ostrich egg.
Structure of a cell.
Most parts of a cell have a definite shape, structure
and function called Cell Organelles.
1. Cell wall (only in plant cell): -
Main characteristics Chief Function
Outermost in plant Gives rigidity and
cell. shape
