Chapter 11

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Chapter 11
2010-11-12 15:29:26
Cellular Molecular Biology

Membrane transport and membrane electrical properties
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  1. Na+ concentration is ____ inside the cell and ____ outside the cell
    • lower in the cell
    • higher outside the cell
  2. K+ ions are found in ____ concentration inside the cell compared to _____ concentration outside the cell.
    • Higher inside the cell
    • lower outside the cell
  3. Mg2+ is found ____ concentration inside the cell and ___ concentration outside of the cell
    • lower inside the cell
    • higher inside the cell
  4. Ca2+ is found in ____ concentrations inside the cell compared to ____ concentrations outside of the cell
    • lower concentration inside the cell
    • higher concentrations inside the cell
  5. H+ is a cation found in similar concentrations but it is slightly ____ inside the cell and slightly ___ outside the cell
    • higher inside the cell
    • slightly lower outside the cell
  6. Cl- concentration is ____ inside the cell and ____ outside the cell
    • lower inside the cell
    • higher outside the cell
  7. substances pass across the lipid bilayer via ____ ____
    simple diffusion
  8. The rate that a substance will diffuse across the lipid bilayer is determined by these 2 factors;
    SIZE of the substance: the smaller the substance, the higher the rate of diffusion

    • lipid solubility:
    • the more hydrophobic/nonpolar, the higher the rate - more important than the size, as it determines the rate of diffusion
  9. Ions are highly ____ when trying to cross the phospholipid bilayer
    • impermiable
    • inluding amino acids
  10. ____ _____ proteins allow polar substances to pass across a membrane. But, these have high _____
    • membrane transport proteins
    • specificity
  11. A solute that can not pass through a cell membrane enters the cell via ____
    transporter permease; or carrier
  12. Diffusion of a specific solute (usually an _____ ___) diffused through an _____ pore; a channel protein
    inorganic ion; aqeous
  13. uncharged substances move down the ____ gradient;
    charged substances move down the ________ gradient
    • concentration gradient
    • electrochemical gradient
  14. _____ transport requires energy input
    this transport transports ____ the concentration gradient
    • active
    • against
  15. Energy input for active transport comes from _____ or an ____ gradient
    • ATP
    • Ion gradient
  16. therefore, transport by channel proteins is always ___ but transport by transporters can be ___ or _____
    • passive
    • passive or active
  17. This type of transport requires no membrane protein and no energy input
    what is simple diffusion?
  18. In transport models, the concentration of transported molecule is not affected by saturation
    what is simple diffusion
  19. In transport proteins, the solute adheres to the ___ ____ of the protein causing a shape change
    solute-binding site
  20. in____ transport, solutes are transported against the electrochemical gradient. Name 3 ways this can be acheived.
    • active
    • 1)Coupled transporter
    • 2) ATP-driven pump
    • 3) light-driven pump
  21. The are _ major classes of ion channel transporters. What are they?
    • 3
    • uniport, symport and antiport
  22. There are _ types of ATP-driven pumps found in both prokaryotic and eukaryotic pumps
  23. This type of ATP-driven pump is found in plasma membrane of bacteria, the inner membrane of mitochondra, and thylakoid membranes of chloroplasts
    F-type pump ("f" derivied from "factor")
  24. these pumps use H+ gradients across these membranes to drive the synthesis of ATP
    and are also known as ___ ____
    • F-type pumps
    • ATP-synthases
  25. This type of diffusion/transport contains membrane transport proteins called Transporter pumps
    Active transport
  26. This type of diffusion/transport contains membrane transport proteins called Transportera and channels
    Facilitated Diffusion
  27. This type of diffusion/transport is the only one of its type that does NOT reach saturation
    simple diffusion
  28. In passive transport, a solute binds to the ____ ____ site of the membranous protein to cause a _____ change in the protein mediating the transport
    solute-binding site

    shape change
  29. Active transport can be driven by ____. There are 3 major classes of transporters driven by ___.
    ion gradients/ ion gradients

    3 classes; 1)Uniport 2) symport (co-transporter) 3) Anitport (exchangers)

    2 and 3 are coupled transport
  30. This pump is an example of secondary active transport; driven by an ion gradient NO ATP is directly required.
    This differs from _____ active transport that is driven by ATP hydrolysis (eg Na + or K+ pump)

    this is a _____ pump
    Primary active transport (require ATP hydrolysis)

    Glucose pump
  31. ion gradients are established by _____ <-- ATP hydrolysis
    there are _ major classes of ATP-driven pumps
    - all _ major classes are found in ____prokaryotic/eukaryotic cells
    • ion pumps
    • 4
    • 4
    • both cell types
  32. A __ type ion pump phosphorylates themselves during the pumping cycle
  33. this kind of pump is found in the __ ___ of bacteria and inner membrane of mitochondria as well as the ____ membrane of chloroplasts. This type of pump is also called ATP synthases.
    This kind of pump is called a ___ pump.
    • plasma membrane (bacteria)
    • Thylakoid membrane (chloroplasts)
    • F-type pump
  34. V-type ATPases (V from vacuole) are structurally related to ____ pumps except the v-pump works in the _____ direction
    • F-type
    • reverse
  35. ___ transporters are they largest family of membrane transport proteins. Unlike the other three classes of pumps, these transporters also pump ____ across the membrane.
    • ABC transporters
    • small molecules
  36. one important example of a pump is a P-type pump called the ____
    Na+-K+ pump and is an antiporter
  37. Binding of Na+ triggers ________________ while binding of K+ triggers ________
    • autophosphorylation (N)
    • dephosphorylation (K)
  38. The Na+ - K+ pump helps the ___ ___ ____ in animal cells and regulates ____ ____ (affects movements water via osmosis through lipid bilayer and aquaporins)
    • resting membrane potential
    • cell volume
  39. In a ____ environment the cell crenates (shrinks). In a ___ environment the cell swells and will even lyse. A normal shaped cell is in a ____ environment.
    • hypertonic
    • hypotonic
    • isotonic
  40. Ion channels have an _____ pore that permits _____ of ions. They have 2 important characteristics.
    1)______ 2)_____
    • aqueous pore
    • diffusion
    • 1) ion selectivity (narrowest part of chanel called selectivity filter)
    • 2) most ion channels are gated (usually closed will open briefly in response to stimulus)

    * if the stimulation is prolonged, most channels go into a closed inactivated stated
  41. there are >___ types of ion channels

    an individual neuron can have >__ types of ion channels
    • 100
    • 10
  42. the most common channels are _____. Some are permanently open and they are called ___ _____
    They play an important role in the establishment of the ___ ___
    • K+
    • K+ leak channels
    • membrane potential
  43. membrane potential exists when there is an ___ distribution
    of + and - ions on both sides of a membrane . When such distribution occurs the membrane becomes ____
    • unequal
    • polarized
  44. A membrane potential exists due to these 3 things?
    • 1) action of Na+- K+ pump
    • 2) electrochemical gradients for K+, Na+, Cl- ect
    • 3) differential permeability of the plasma membrane
  45. neurons are capable of transmitting electrical signals called ____ ____. Ion channels play a critical role in the function of nuerons.
    nerve impulses ( action potentials)
  46. Describe the direction of movement of a nerve impulse as it is triggered throught the nerve
    dendrties --> axon --> terminal branches of axon
  47. triggering of an action potential is a ____ feedback cycle
    positive feedback cycle
  48. In action potential, what step cuases more (additional) influx of Na+ ions
    a slight depolarization ; opening of voltage-gated Na+ channels
  49. Past resting membrane potential, the cell ____ in voltage and depolarizes. Post depolarization, the cell _____ in voltage and repolarization occurs
    • increases
    • decreases
  50. an action potential is triggered only only if the depolarization reaches the _____ level. The AP causes depolarization of the neighouring region of the plasma membrane.This in turn triggers ___ of APs along the axon
    - i.e., a nerve impulse is transmitted along the axon
    • threshhold
    • propagation
  51. the speed of neural transmission on vertebrates is increased by the presense of a ____ _____
    myelin sheath
  52. Myelin sheaths are present in segments seperated by nodes of Ranvier. In brain and spinal cord these segments are known as _____ while in typical nerve it is called _____ cells. The conduction on the impulse transmission is termed ______ conduction
    • oligodendrocytes
    • Schwann cells
    • Saltatory conduction
  53. Some nuerotransmitters are ______ neurotransmitters. They open ___ ____. The resulting influx of Na+ ions causes a ____ _____ of the postsynaptic membrane. Therefore the membrane potential is now closer to the threshold level.
    ie. an _____________(EPSP) is briefly genertated
    eg. acetylcholine, glutamate & serotonin are usually excitatory neurotransmitters
    • Excitory neuritransmitters
    • cation channels
    • slight depolarization
    • excitatory postsynaptic potential (EPSP)
  54. Seome neurotransmitters are _____ Neurotransmitters. The open __channels or ___ channels. The resulting eflux of ___ ions or influx of ___ ions causes a slight _______ of the postsynatic membrane. Thereofore, the membrane potential is now farhter from the threshold level.
    ie. an __________ (IPSP) is briefly generated
    ed. GABA and glycine are usually inhibitory nuerotranmitters
    • inhibitory neurotransmitters
    • opens K+ channels or Cl- channels
    • efflux - K+ ions ; influc Cl- ions
    • slight hyperpolarization
    • inhibitory postsynaptic potential (IPSP)
  55. 5 major types of gated ion channels left are involved when a neuron stimulates contraction of a skeletal muscle cell:
    • 1) voltage-gated Ca++ channels
    • located in the axon terminal membrane

    • 2) acetylcholine-gated cation channels
    • also called acetylcholine receptors

    3) voltage-gated Na+ channels

    • 4) voltage-gated Ca++ channels
    • located in the transverse tubules of the muscle cell

    • 5) Ca++-gated Ca++ release channels
    • - located in the sarcoplasmic reticulum membrane