bio exam 2 ch. 5

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bio exam 2 ch. 5
2013-06-19 10:41:11
chapter bio exam

ch 5, membrane structure and function
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  1. 3 properties of plasma membrane
    • Common: to all cells
    • Separates: cell contents from environment (holds things in)
    • Phospholipid bilayer: barrier of hydrophobic and hydrophilic things
  2. what does the plasma membrane regulate
    endo and exoytosis
  3. 3 components of plasma membrane
    • Lipid component (phospholipid bi-layer)
    • Protein molecules (within the bi-layer)–Integral proteins: proteins partially or wholly embedded in the membrane itself
    • –Peripheral proteins: do not go all the way through the bi-layer; is only on the outer layers
    • Cholesterol–Affects the fluidity of the membrane; lies underneath the membrane giving it support and structure
  4. 3 functions of membrane proteins
    • Channel Proteins: allow passage of particular molecules or ions via a channel (line tunnels in the membrane) passive; no energy required
    • Carrier Proteins: actively carries a molecule thru the membrane energy required; or changes the molecule’s shape; passive, no energy required
    • Cell Recognition Proteins: mostly glycoproteins (have a carbohydrate chain attached to it) identification friend or foe Ex. Histocompatibility complex
  5. 3 types of proteins in plasma membrane
    • Receptor Proteins: lock/ key mechanism. only a molecule with the right physical shape can fit in them; like a lock and key
    • Enzymatic Proteins: catalyze specific reactions (facilitate reactions) in the picture, the protein makes a reaction where the brown thing turns to the purple triangle
    • Junction Proteins: holds cells together; form junctions between cells  (between phospholipid bi-layers of those cells; see picture on 14. phospholipid bi-layers shown are of two different cells)
  6. 3 steps of cell signaling
    • 1. binding of the signaling molecule
    • 2. transduction of the signal
    • 3. response of the cell depending on what type of protein is targeted
  7. permeability of the plasma membrane
    selectively permeable; small non-charged molecules move freely across the membrane flowing down a concentration gradient
  8. concentration gradient
    the way these molecules move across the plasma membrane
  9. diffusion
    • movement of molecules from a higher to lower concentration; down their concentration gradient; until equilibrium is achieved (passive)
    • Diffusion works as a transport mechanism as long as the substance to be transported is small, and the concentration gradient is favorable (high to low concentration).
  10. active transport
    when molecules move against concentration gradient. requires energy
  11. bulk transport
    bulk transport: a way that large particles enter or exit a cell
  12. exocytosis
    exocytosis: moving a particle outside of the cell
  13. endocytosis
    endocytosis: move a particle into the cell
  14. 3 types of endocytosis
    • phagocytosis- large solid material gets engulfed and surrounded by vesicles
    • pinocytosis- liquid or very small particles
    • receptor-mediated endocytosis: pinocytosis using receptor proteins to recognize compatible molecules and bring them into the cell
  15. 2 types of passive transport
    2 types of active transport
    • diffusion and facilitated transport: passive
    • active and bulk transport: active
  16. solution contains
    a solute and a solvent
  17. solvent
  18. solute
    dissolved solid
  19. osmosis
    movement of water across a semi-permeable membrane from high to low concentration
  20. osmotic pressure
    pressure that develops due to osmosis
  21. difference between diffusion and osmosis?
    • osmosis is the movement of water across a semi-permeable membrane
    • diffusion is movement of molecules down a concentration gradient
  22. how is the strength of a solution defined
    The strength of solution is defined as the amount of solute in grams present in one liter
  23. isotonic solutions
    • no net gain or loss of water by the cell
    • solute and water concentration equal on both sides of the membrane
  24. hypotonic solutions
    • Hypo- less than (low salt/no salt)
    • solution with a lower concentration of solute outside the cell than inside the cell
    • cells placed in a hypotonic solution will swell
    • fish in fresh water (has to pee because cells are always swelling with water)
  25. hypertonic solution
    • hyper- more than (lots of salt)
    • solution with a higher percentage of solute outside the cell than inside the cell
    • cells placed in hypertonic solution will shrink
    • fish in salt water (has to drink because cells are always shrinking)
  26. crenation in animal cells
    when animal cells are placed in a hypertonic solution (shrink)
  27. plasmolysis in plant cells
    when plant cells are placed in hypertonic solution (shrink)
  28. hemolysis
    bursting of blood cells
  29. turgor pressure
    when a plant cell swells due to a hypotonic solution
  30. facilitated transport
    • how molecules are rapidly transported across the plasma membrane
    • passive; following concentration gradient from high to low concentration
  31. active transport
    • movement against concentration gradient  from low to high concentration
    • requires energy
    • facilitated by carrier proteins called pumps
  32. co-transport
    how the concentration gradient is maintained; two proteins that work together
  33. countertransport
    the protein is moving one molecule in one direction and another molecule in a different direction
  34. 3 types of junctions in animal cells
    • adhesion junction
    • tight junction
    • gap junction
  35. adhesion junction
    adhesive proteins connect two cells
  36. tight junctions
    tight junctions between cells form an impermeable barrier because their adjacent plasma membranes are joined and don't allow molecules to pass
  37. gap junctions
    allow communication between two cells because adjacent plasma membrane channels are joined
  38. plasmodesmata
    numerous narrow, membrane-lined channels that pass through the cell wall