CELL: The Unit Of Life

==The cell is the fundamental structural and functional unit of all living beings. It is the smallest part of the body of an organism which is capable of independent existence and of performing the essential functions of life.==

@@Red Blood cells die after 120 days.@@

@@Most organisms, like humans start life as a single cell called zygote.@@

The first microscope was created by scientist Antony van Leeuwenhoek. These microscopes could zoom up to 200x times and used single biconvex lenses. This was called simple microscopes.

Robert Hooke created the compound microscope. Which could zoom up to 2000 times and uses double biconvex lenses.

Electron microscopes can zoom up to 20,000x.

CELL THEORY

• The cell is the smallest unit of structure of all living things.
• The cell is the unit of function of all living things.
• All cells arise from pre-existing cells.

%%CELLS: HOW MANY?%%

• %%The bigger an organism, greater is thx e number of cells in its body%%
• %%Unicellular: Many small plants and animals are made up of just one single cell. Eg. Bacteria, Yeast, Amoeba%%
• %%Few-Celled: Some very small plants and animals are made up of relatively fewer number of cell, few hundred or few thousands. Eg. Spirogyra, Volvox.%%
• %%Multicellular: Organisms with millions and billions of cells. Eg. Human Beings, Mango Trees.%%

CELLS: HOW SMALL?

Smallest:

• Bacteria: 0.3-5.0 um
• Mycoplasma: 0.15 - 0.3 um
• RBCs: 7 um

Longest:

• Nerve Cells

Largest:

• Ostrich Egg