Tuesday, 17 January 2017

Class 8 Biology ( Cell)

Cell

  • Robert Hooke discovered dead cell in 1665.
  • Anton Van Leeuwenhoek discovered first living cell in 1674.
  • Robert Brown discovered nucleus in 1831.
  • Purkinje gave the term cytoplasm.
  • T.H.Huxley described protoplasm as "physical basis of life" in 1868.
  • Rudolf Virchow stated "omnis cellulae cellua" I.e all cells arise from preexisting cells.
  • The German botanist Scheilden and the German physiologist Schwann in 1838 gave the cell theory.
  • The single celled organisms are called unicellular organisms.
  • Organisms made of more than one cell are called multicellular organisms.
  • Shapes of cells of bacteria are bacilli,spirilla,coccus,vibrio.
  • Pleomorphism is the ability of few cells to change its shape during their life cycle.
  • A small cell is more efficient than a larger one.
  • Cells are measured in microns.
  • Mycoplasma is the smallest cell.
  • Largest cell is ostrich egg.
  • Largest plant cell acetabularia.
  • Longest cell is neuron.
  • Cell membrane gives shape to cells.
  • Cells engulf particles or fluids by endocytosis.
  • Pinocytosis moves liquids into the cell.
  • Phagocytosis moves larger particles into the cell.
  • Cell wall is permeable and is present only in plant cells.
  • Ca and Mg pectates are plant cement.
  • Fruits become soft and juicy as middle lamella dissolves.
  • Cytoplasm present between cell membrane and nucleus.
  • Endoplasmic reticulum is a system of membranes.
  • Protein + Carbohydrate= glycoprotein
  • Golgi Apparatus is middle men of the cell.
  • Ribosome is engine of cell or protein factory.
  • Lysosomes are food processors and digestive bags and suicidal bags.
  • Centrosomes help in cell division.
  • Peroxisomes,Glyoxisomes,Sphaerosomes.
  • Mitochondria is power house of cell.
  • Chloroplast is kitchen of cell.
  • Nucleus carries genetic material

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