Cell the Unit of Life

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Chapter-8
Cell: The Unit Of Life
What is a cell?
Cell is the basic or fundamental structural and functional unit of an organism.

What is cell biology?
The branch of biology that deals with the study of cell structure and function is called cell biology.

DISCOVERIES;
Who discovered cell?
Robert Hooke observed a live cell in 1665. He observed the cell(actually the cell walls) in the slice of cork under his compound microscope ,coined the term cell, recorded his observations in micrographic.

What is the contribution of Anton Von Leewenhoek to biology? 1)Obsevation of live cells of baacteria and protozoans called them as animal cules in 1667. 2)Discovery of Electron Microscope. First microscope which perfects the techniques of grinding microscope(bacteria).

What is the contribution of Rudolf Virchow?
Rudolf Virchow in 1885 put forward the theory of cell lineage and stated that cells always develop from pre-existing cells by cell division (Omnis cellula e cellula).

CELL THEORY
Who proposed the cell theory?
Matthias Schleiden a German botanist observed all the plants are composed of different kinds of cells which forms the tissues of the plant in 1838 and Theodere Schwann a British Zoologist studied different types of animal cells that had a outer layer called Plasma Membrane in 1839. Theodere Schwann and Matthias Schleiden formulated the cell theory. Features of cell theory:

1)All organisms are made up of cells and their product.
2)Cell is the structural and functional unit of life.
3)A Cell originates from a pre-existing cell, by the process of cell division. Modern cell theory:
* Also called as the Cell Principle or Modern cell theory. * Modified by Schwann and Rudolf Virchow
Main features of modern cell theory
* Cell contains cell organelles.
* Cell live independently but organelles cannot.
* Cell is capable of not only maintaining itself but is also able to propagate itself. * Life exists in the form of the...
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