Cells

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Cells

  1. 1. CELLS<br />
  2. 2. Defination of cell<br />Cell is a structural and functional uint of life. It is also called fundamental unit of life.<br />
  3. 3. About cell<br />Cells were first discovered by Robert Hooke in 1665. While examinig a thin slice of cork , Robert Hooke saw that the cork resembled the structure of a honeycomb consisting of many little compartments. Cork is asubstance which comes from the bark of a tree. Hooke observed these cork slices through a self-designed microscope.Robert hooke called these boxes cells. Cell is a Latin word for ‘a little room.’<br />
  4. 4. Difference between Prokaryotic and eukaryotic<br />Prokaryotic cell<br />Eukaryotic cell<br />Size of cell is small.<br />Nucleus is absent.<br />It contain single chromosome.<br />Nucleolus is absent.<br />Membarane bound cell organelles are absent.<br />Cell division takes place by fission dr budding.<br />Size of cell is large.<br />Nucleus is present.<br />It contain more than one chromosome.<br />Nucleolus is present.<br />Cell organelles such as plastids, lysosomes etc. are present.<br />Cell division occures by mititic and meiotic.<br />
  5. 5. Cell Theory<br />In 1938, Jakob Matthias Schleiden(1804-1881), a German botanist, first proposed the idea that all plants consist of cells. A year later, in 1839, Theodor Schwann(1810-1882), a German zoologist, independently asserted that all animals and plants are made up of cells. This joint finding forms the basis of the cell theory.<br />The cell theory was refined furtherin 1885, when another German biologist, R. Virchow presented the idea that all cells arise from pre-existing cells. Thus , cell theory comprises some postulates. <br />
  6. 6. Postulates of cell theory<br />All organisms are composed of cells and cell products.<br />All metabolic reactions takes place in the cells. Thus, cells are structural and functional units of life.<br />All cells arise from pre-existing cells only.<br />Every organisms starts its life as a single cell.<br />
  7. 7.
  8. 8. Plant cell<br />In plant cell, Cell wall, plasma membrane, nucleus, chromatin, endoplasmic reticulum, cytoplasm, chloroplast, ribosomes, mitochondria, dictyosome vacuole are present.<br />
  9. 9. Animal cell<br />In animal cell, plasma membarane, cytoplasm, nucleus, chromatin, ribosomes, mitochondrion, endoplasmic reticulum, golgi apparatus, golgi vesicle, present.<br />
  10. 10. Present in both plant and animal cell<br />Plasma membrane, ribosomes, cytoplasm, mitochondrion, endoplasmic reticulum, nucleus, chromatinare present. In plant cell golgi apparatus is known as dictyosome.<br />
  11. 11. Differances between plant cell and animal cell<br />Plant cell<br />Animal cell<br />Size of cell is large.<br />Cell wall is absent.<br />Plastids are present.<br />Plant cell have a big vacuole.<br />Plant cell have many simpler units of golgi apparatus, called dictyosome.<br />Plant cells have centrosomeand centrioles.<br />Size of cell is small.<br />

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