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Physiology > Membrane transport > Flashcards

Membrane transport Flashcards

1
Q

What are the three different forms of membrane transport?

A

Passive, active, vesicular

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2
Q

Is simple diffusion active or passive transport?

A

passive

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3
Q

Is diffusion through channels (e.g. aquaporins) active or passive transport?

A

Passive

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4
Q

Is facilitated diffusion active or passive transport?

A

Passive

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5
Q

What is the difference between primary and secondary active transport?

A

Primary = direct usage of ATP

Secondary = ATP used to pump another ion across membrane, then that used to symport/antiport

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6
Q

What are the two forms of vesicular transport?

A

Endocytosis

Exocytosis

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7
Q

What is uniport?

A

Carrier transport for only one substance (glucose example)

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8
Q

What is carrier-mediated transport?

A

Symport vs antiport

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9
Q

What are the molecules that can diffuse through a membrane?

A

gases, and small, uncharged, polar molecules

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10
Q

Increased lipid solubility increases or decreases simple diffusion?

A

Increases

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11
Q

As the molecular size increases, the diffusion rate … (?)

A

Decreases

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12
Q

The rate of diffusion (blanks) as the thickness of

membrane decreases.

A

increases

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13
Q

How does concentration gradient affect the speed of simple diffusion?

A

Increases speed as [C] increases

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14
Q

The larger the membrane surface area, the (blank) the rate of net diffusion?

A

The larger the surface area, the larger the rate of net

diffusion.

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15
Q

How does temperature affect the permeability of cell membranes?

A

Incresaes permeability as temp rises

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16
Q

Is the composition of the lipid bilayer a factor that affects the speed of diffusion through a cellular membrane?

A

Yes

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17
Q

What are the three factors that affect the rate of diffusion through channels?

A
  1. Permeability (# of open channels)
  2. Selectivity/affinity
  3. Concentration gradient
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18
Q

How are aquaporin regulated?

A

Brought to cell surface just like the GLUT transporters

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19
Q

What is the cause of nephrogenic diabetes insipidus?

A

A defect in one of the types of aquaporins in the glomerulus of the kidney

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20
Q

What are the two factors that affect the diffusion of ions through ion channels?

A

Concentration gradient and voltage

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21
Q

What are the three types of gated ion channels?

A

Voltage gated
Ligand gated
Mechanically gated

22
Q

What is facilitated diffusion?

A

Specific transport of a single type of molecule down its concentration gradient

23
Q

Is the rate of diffusion of ions through an ion transporter higher, lower, or equal to that of facilitated diffusion?

A

Higher, duh

24
Q

True or false: there is a linear relationship between the increased in the rate of diffusion of an ion through its transporter, and its concentration?

A

False–hyperbolic with Vmax.

25
Q

Is transport direction reversible in ion channels?

A

Yes

26
Q

What is Km for a facilitated ion channel?

A

[C] at which v =0.5(Vmax)

27
Q

Can facilitated transport transport uncharged substances against their concentration gradient?

A

No

28
Q

Can facilitated transport transport ions against their electrochemical gradient?

A

No

29
Q

What allows the GLUT transporter to continue to transport glucose at a high rate despite taking in large amounts of glucose?

A

Phosphorylation of glucose to G6P

30
Q

Does active transport approach a maximum rate of transport? Can it show competitive or noncompetitive inhibition?

A

Yes, yes, and yes

31
Q

The Na/K pump is used for what?

A

Maintaine normal membrane potential and preventing cell swelling due to influx of Na

32
Q

What are ABC transporters?

A

ATP bind cassette–proteins that use ATP for transport (either hydrolyze or just for regulation)

33
Q

What type of transporter is the CFTR protein?

A

Active (ABC family)

34
Q

A mutation in the CFTR protein results in what disease discussed in class?

A

Cystic fibrosis

35
Q

What is the gene that causes NDI?

A

Mutations in the aquaporin-2 gene

36
Q

How the the Vmax curve shift with increases in [C]? Km? Transporter numner

A

[C] = get closer to Vmax

Km= shifts curve right

Transporter = increases Vmax, no change in Km

37
Q

For secondary active transport, what must happen in order for the transport to work [hint, not energy change or ATP binding]?

A

One of the molecules has to move down its [C] gradient

38
Q

What are the MDR proteins? What is their clinical significance?

A

Multi-drug resistant proteins.

These are ABC trasporters that, when overexpressed, cause clinicially important resistance to CA drug therapy

39
Q

What is an example of antiport?

A

Movement of Na ions with glucose in the intestines

40
Q

What is the action of Na/K/Cl transporters?

A

co-transport of 1 Na:1K:2Cl from extracellular

fluid to cytosol

41
Q

What are the two examples given in class of ion exchange/counter pumps?

A

Na/Ca exchanger to pump out Ca

Na/H to pump out H and bring in Na

42
Q

True or false: vesicular transport requires energy?

A

true

43
Q

What type of molecules does vesicular transport?

A

Large ones

44
Q

What are the three types of vesiicular transport?

A
  1. Phagocytosis
  2. Pinocytosis
  3. Fluid-phase endocytosis
45
Q

True or false: all cells perform pinocytosis?

A

True

46
Q

What is fluid phase endocytosis? What are the proteins needed for this to occur (usually)?

A

uptake of materials that are dissolved in ECF usually via clatharin coated pits and adaptin

47
Q

What happens when the adaptin/clatharin coated vesicles are endocytosed into the cell?

A

Adaptin and clatharin recycled, vesicle ready to fuse

48
Q

True or false: fluid-phase endocytosis is a very efficient way to transport a specific
substance into the cell.

A

False- very inefficient

49
Q

What biochemical process is dependent on receptor mediated endocytosis?

A

LDLs

50
Q

What is caveolae endocytosis?

A

Similar to clathrin mediated endocytosis but the process uses caveolae and
caveolin as the coating protein.

Caveolae are well-defined invaginations
in the plasma membrane (diameter ~ 100 nm).

Physiology (75 decks)

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