cell biology b1

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  • Cell biology
    • Cells
      • Eukaryotes are complex organisms which include all animal and plant cells.
        • Eukayotes made out of eukaryotic cells
      • Prokaryotes - are small, simple cells, like bacteria. They are single-celled
        • Prokaryotes made of prokaryotic cells.
        • Bacteria dont have a 'true' nucleus, chloroplasts or mitochondria.
          • They have plasmids.
      • Animal and plant cell structures
        • Nucleus - contains genetic material that controls cell activity.
        • Cytoplasm - gel like substance where most chemical reactions happen.
        • Cell membrane - holds cell together and controls what goes in and out.
        • Mitochondria - site of aerobic respiration, this transfers energy needed for cell to work.
        • Ribosomes - where proteins are made in cell.
      • Plant only structures
        • Rigid cell wall - supports and strengthens cell. It is made of cellulose.
        • Vacuole - contains cell sap, sugars and salts.
        • Chloroplasts - where photosynthesis occurs which makes food for plant. Contains chloroplasts.
    • Microscopy
      • Light microscopes
        • Use light and lenses to form image of specimen and magnify it.
          • They let us see individual cells and large subcellular structures like nuclei.
      • Electron microscopes
        • Use electrons to form an image. They have a higher magnification and resolution than light microscopes.
          • Let us see small things like internal structures.
      • Magnification== image size / real size
    • Differentiation
      • When a cell changes to become specialised for it function
        • develop different subcellular structures
        • Sperm speciallised for reprod, nerve cells....
      • Most animal cells only can differentiate as embryos wheres plants can differentiate throughout whole life
      • undifferentiated cells = stem cells
    • chromosomes and mitosis
      • Chromosomes contain genetic info. Nucleus contains genetic material in form of chromosomes.
        • 23 pairs of chromosomes in a human  cell.
      • mitosis
        • dividing of cells. Multicellular organisms use mitosis to grow or replace damaged cells
          • producees 2 genttically identical daughter cells. clones of parent
    • stemcells
      • can turn into any type of cell
        • stem cells are found in 2 places: human embryos or bone marrow
      • May be able to cure many dieassse, e.g. diabetes and parralysis
      • stem cell use controversial as each embryo a potential human life
      • stem cells used in plants. found in meristems
        • stem calls can produce plants quickyl and cheaply, prevent extinction of rare plant species and grow disease resistant crops
    • diffusion
      • the movement of particles from an area of high conc. to an area of lower conc.
      • the bigger the conc gradient, the faster the diffuion rate
      • higher temp = faster diffusion rate as particles have more enrgy so move mroe.
    • osmosis
      • movement of water molecules from an area of high water conc to low water conc through a partiallt permeable membrane
        • water molecules can ppass both ways through membrane during osmosis
    • active transport
      • when substances move agianst a conc gradient, from a lower ocnc to a higher con
      • root hairs take in minerals and water by using active transport
        • essential for plant growth
      • active transport is used in the gut when there is a higher of nutrients in the gut but a lower of nutrients in the blood
    • exchange surfaces
      • Cells can use diffusion to take in substances they need and to get rid of waste products
        • How easy it is for the organism to exchange surface with its environment depends on the organisms surface area to volume ratio.
          • Multi cellular organisms have a small surface area to volume ratio


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