Mind map

Membranes: Bio110-2016

cara brand Biology English

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Components of a membrane
- cholesterol: a saturated fat. When conc. inc. in a membrane, fluidity dec
- phospholipids: fatty acid lipids which assemble via hydrophobid interactions. Can move within the plane of the membrane
  - Saturated v. Unsaturated fatty acid tails: Saturated fatty acid tails are very straight and can pack together tightly. When conc. inc. of sat. fat. acids, fluidity dec.
  - Long tails have more opportunity for hydrophobic interactions and therefore can pack more tightly. When length of fat. acids inc, fluidity dec
- Proteins: must have hydrophobic "interiors" made of alpha helices to pass through membrane
  - Made on the Rough Endoplasmic Reticulum
Movement through a membrane
- Passive transport: requires no E to move molecules down a conc. gradient
  - Diffusion: random movement of molecules
  - Facilitated Diffusion: uses a protein to move molecules
    - Osmosis: movement of Water through a membrane with Aquaporins
      - Hypertonic Solution
      - Isotonic Solution
      - Hypotonic Solution
      - KIDNEY FUNCTION
        Nephrons
        Glomerulus: where small mol. from blood are forced into glomerulus tubules via blood pressure. Cells not held together here
        Bowman's Capsule. Cells held together via tight junctions
        Proximal Convoluted Tubules
        Salt and nutrients ACTIVELY pumped out
        As salt conc. dec, water conc. inc. inside tube (hypertonic). Therefore water flows out, down gradient
        No ADH receptors
        Loop of Henle
        Distal Convoluted Tubules Water conc. regulated
        Salt and nutrients continue to be pumped out
        Water transport is regulated. If water is not needed, then no aquaporin and water becomes waste (dilute urine). If water needed by the body, aquaporins are present and water is reabsorbed (conc. urine)
        Cells have ADH receptors. When ADH present, aquaporins present on membrane. When ADH absent, no aquaporins
        Collecting Duct
        Water transport further regulated
        Descending loop. At the bottom, osmotic pressure VERY high. Water still leaves due to very high U/P ratio (osmotic pressure)
        In mammal for further conc. of urine
        Ascending loop: Only salts move out of the tube
    - Carrier Proteins: eg Glucose.
    - Channel Proteins: eg aquporins, always open
      - AQUAPORINS
    - Gated-channel proteins: responds to a stimulus/ligand
- Active transport: eg: Na/K pump. requires energy to move molecules AGAINST a conc. gradient. Uses ATP as energy
- Vesicles