Cells, Tissues and Organs

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  • Created by: rm715
  • Created on: 29-02-16 10:47
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  • Cells, Tissues and Organs
    • Cells
      • Palisade Cells
        • Found in top of leaf closest to surface
        • Carry out photosynthesis and make plant food
        • Packed with chloroplast to absorb sunlight
      • Cilia Cells
        • Lines air passages down to lungs
        • Has tiny hairs called cilia which sweep mucus, dust and bacteria back up the throat to be swallowed
        • Smokers often have a build of mucus as the hairs die and this leads to 'smoker's cough'
      • Egg Cell
        • Contains yolk that acts as food source for the developing embryo when fertilised
        • Carries mother's DNA
        • Much larger than normal animal cells
        • Sperm Cell
          • Long tail to swim to find egg. Enzymes in head.
          • Made in testes of male
          • Carries father's DNA to egg
      • Nerve Cell
        • Elongated with many branches on each side
        • Axis is covered in fat to prevent electrical impulses affecting surrounding tisuse
      • Root hair cell
        • Large surface area to absorb water
        • Thin cell wall to allow water to pass through
        • Absorbs minerals and water from soil
      • Blood cells
        • White blood cells
          • Able to join and change shape
          • Engulfs bacteria and diseases so microbe cannot affect the body
        • Red blood cells
          • Concave, no nuceus and large surface area to make more room for oxygen
          • Carries oxygen from lungs to the body and carbon dioxide to the lungs
    • Enzymes
      • Biological catalysts - speed up biological reactions
      • Proteins made of amino acids
        • DNA codes the amino acids
      • Active site is where subtrates fits in and splits to make products molecules
        • Above an optimum pH or temperature, they become denatured and the active site is destroyed
      • Example: above pH 7 (pH of mouth) , amylase becomes denatured. Reaction rate slows down and sugar is no longer produced
    • Diffusion
      • Movement of particles across a semi permeable membrane from a high concentration to a low concentration to reach an equilibrium
        • Cell membranes allow small dissolved substances to pass through from a high concentration to a low concentration
      • Osmosis
        • Movement of water across a semi-permeable membrane to dilute a high concentration solution
          • Solutions with more water in the cell than outside, are called Hypertonic. Water will move out of the cell
            • A plant sell would be called Turgid. The cell wall keeps the plant supported.
        • Solutions with more water outside the cell than in are called Hypotonic. Water will move into the cell.
          • Solutions with the same concentration of water both inside and outside the cell are called Isotonic. Water will not move
            • Solutions with more water in the cell than outside, are called Hypertonic. Water will move out of the cell
              • A plant sell would be called Turgid. The cell wall keeps the plant supported.
          • A plant cell would be called Flaccid, then would Plasmolyse (shrink)
      • Active Transport
        • The movement of substances against the concentration gradient, travelling from a low concentration to a high concentration
          • Root hair cells use active transport to allow the plant to absorb minerals from a very dilute solution
          • In humans, where there is a low concentration of nutrients in the blood, the glucose and amino acids will diffuse into the blood, against the concentration gradient

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