January 27, 2007

ORGANIZATION OF LIFE = CELL

Cell The basic unit of the body is called cell.In the early days, when the lenses or microscopes had how the bodies of

`living not yet been invented, man was not aware of organisms were made? Whether they possess an undivided body, in which different organs (in animal, bones and blood vessels) are arranged systematically ortheir bodies are made up of small identical structural units, as bricks form a building.

The discovery of cell and theoryROBERT HOOK (1665)Robert hook first studied thin slices of cork and lea yes under compound microscope .He noticed in them small box like chambers of the small size, which he named as cell..ROBERT BROWN (1831-1833)Robert brown discovered nucleus mettle cell.MATHIAS SCHLEIDEN (1838)Mathias schleiden a German botanist claimed that all plants were made up of cells.THEODRE SCHWANN (1839)Theodre Schwann ascertaining that animal were also made up of cells which are similar to plant cells.Thus schleiden and Schwann propounded cell theory be all organism are made from cells.J. PURKINJI (1840)

Prepared by: Saira Mobeen COM Student UE, Jauharabad.

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January 27, 2007

J. purkinji used the term protoplasm for the materials found in the cell.

Structure of cellCells are basically of two types.PROKARYOTIC.Prokaryotic cells have no membrane bounded nucleus and subeellularorganelles.EUKARYOTIC.

Eukaryotic cells have a membrane bounded nucleus and organelles. Difference between prokary and eukaryotic cellProkaryotic cell Eukaryotic cell

1. The organisms made of prokaryotic 1.The organisms made of enkaryotic cell are prokaryotic e.g. bacteria and cell are enkaryotic e.g. animal,

Cyamobacteria. Plants, fungi and protests.2.Chromosomes are present in the 2.Chromosomes are present in Cytoplasm. Nucleus.3. Ribosomes are small size. 3. Ribosomes are of large size.4. Cell wall is composed of murein. 4.Cell wall of plant cell is composed of cellulose.5. These cells are simple. 5. These cells are complex.

Prepared by: Saira Mobeen COM Student UE, Jauharabad.

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January 27, 2007

Cell Wall

It is the outer semi rigid and non-living boundary of a plant cell. Thickness of cell wall varies in different cells. Function of cell wall Cell wall provides a definite, shape, protection and support to the cell.Cell MembraneCell membrane or plasma membrane is present in all plants and animal cells. With the help of latest techniques and electron microscopy, different models have been presented to understand the structure of cell membrane.Fluid mosaic model Fluid mosaic model is the most acceptable model. According to this model cell membrane consists of lipid bilayer in which most protein molecules float about.NucleusThe most important a cell is nucleus. Chromosomes are present in nucleus.Number of chromosomes in human being.The number of chromosomes in man’s cell is 46.

CytoplasmCytoplasm is a viscous substance. It contains a variety of organelles and many soluble and insolubles.Function Cytoplasm provides chemicals, site and conditions for various biochemical activities.RibosomesThese are tiny granular structures which are not bounded by membranes. These are formed in the nucleolus and are either freely dispersed

Prepared by: Saira Mobeen COM Student UE, Jauharabad.

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January 27, 2007

in the cytoplasm or attached with endoplasmic reticulum. These are involved in the synthesis of proteins. It is the only organelle which is found in prokaryotic cell.

Endoplasmic ReticulumIt is the net work of channels and cisternac extending throughout the cytoplasm from nuclear membrane to the plasma membrane.

1.Smooth endoplasmic reticulum: It is non granular because ribosomes are not attached on it.These play an important role in lipids formation.2.Rough endoplasmic reticulum: It is granular because ribosomes in the form of small granules are attached on it which are involved in protein synthesis.Endoplasmic reticulum plays an important role in transport of materials form one part of the cell to the other.VacuoleVacuole is a fluid filled structure bounded by a single membrane. Animal cells contain relatively small vacuoles, which are usually more than one in number.

Prepared by: Saira Mobeen COM Student UE, Jauharabad.

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