Membrane EXAM 2

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  1. cell membrane
    • phospholipid bilayer
    • Phospholipids are amphipathic molecules (hydrophophic tail hydrophilic head)
    • Membranes also contain proteins and carbohydrates
  2. fluid mosaic model
    • lipids and proteins can move relative to each other within the membrane
    • Not completely rigid
  3. integral membrane proteins
    Transmembrane proteins - one or more regions that are physically embedded in the hydrophobic region of the phospholipid bilayer

    Lipid-anchored protein - covalent attachment of a lipid to an amino acid side chain within a protein
  4. Peripheral protein
    • Noncovalently bound to regions of
    • integral membrane proteins that project out from the membrane, or they are bound to the polar head groups of phospholipids
  5. semi fluid membrane
    • Fluidity - individual molecules remain in close association yet have the ability to
    • readily move within the membrane

    Semifluid- most lipids can rotate freely around their long axes and move laterally within the membrane leaflet

    • “Flipflop” of lipids from one leaflet to the opposite leaflet does not occur spontaneously
    • -Flippase requires ATP to transport lipids
    • from one leaflet to another
  6. factors affecting fluidity
    • cholesterol
    • double chains in tails
    • legnth of tails
  7. glycolsylation
    Process of covalently attaching a carbohydrate to a protein or lipid

    -Glycolipid – carbohydrate to lipid

    -Glycoprotein – carbohydrate to protein
  8. function of glycolsylation
    Serve as recognition signals for other cellular proteins

    Play a role in cell surface recognition

    protective by coating with glycocalyx
  9. freeze fracture electron microscopy
    Can provide significant three-dimensional detail about membrane protein form and shape
  10. synthesis of membrane parts
    cytosol and endomembrane system work together to synthesize lipids next to smooth ER
  11. transfer of lipids and other membranes
    Lipids in ER membrane can diffuse laterally to nuclear envelope

    Transported via vessicles to Golgi, lysosomes, vacuoles, or plasma membrane

    Lipid exchange proteins – extract lipid from one membrane for insertion in another
  12. passive transport
    • no ATP
    • high to low
    • no protein
  13. facilitated diffusion
    • transport protein/carrier molecule
    • no ATP
  14. active transport
    • needs ATP
    • against gradient (low to high)
    • primary - pump
    • secondary - preexisting pump
  15. gradients
    Transmembrane gradient - Concentration of a solute is higher on one side of a membrane than the other

    Ion electrochemical gradient -Both an electrical gradient and chemical gradient
  16. tonicity
    • hypertonic
    • hypertonic
    • isotonic
  17. osmosis
    movement of water
  18. transport protein
    provide a passageway for the movement of ions and hydrophilic molecules across membranes

    • classes based on manner of movement
    • -Channels (gated)
    • -Transporters (think wheelbarrow/enzyme active site)
  19. exocytosis
    material from inside shipped out via vesicles
  20. endocytosis
    • bring things into the cell
    • Receptor-mediated endocytosis
    • Pinocytosis (fluids)
    • Phagocytosis (food)
Card Set
Membrane EXAM 2
biology exam 2
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