Membrane transport

Question 1

What are the three different forms of membrane transport?

Answer 1

Passive, active, vesicular

Question 2

Is simple diffusion active or passive transport?

Answer 2

passive

Question 3

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

Answer 3

Passive

Question 4

Is facilitated diffusion active or passive transport?

Answer 4

Passive

Question 5

What is the difference between primary and secondary active transport?

Answer 5

Primary = direct usage of ATP

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

Question 6

What are the two forms of vesicular transport?

Answer 6

Endocytosis

Exocytosis

Question 7

What is uniport?

Answer 7

Carrier transport for only one substance (glucose example)

Question 8

What is carrier-mediated transport?

Answer 8

Symport vs antiport

Question 9

What are the molecules that can diffuse through a membrane?

Answer 9

gases, and small, uncharged, polar molecules

Question 10

Increased lipid solubility increases or decreases simple diffusion?

Answer 10

Increases

Question 11

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

Answer 11

Decreases

Question 12

The rate of diffusion (blanks) as the thickness of

membrane decreases.

Answer 12

increases

Question 13

How does concentration gradient affect the speed of simple diffusion?

Answer 13

Increases speed as [C] increases

Question 14

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

Answer 14

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

diffusion.

Question 15

How does temperature affect the permeability of cell membranes?

Answer 15

Incresaes permeability as temp rises

Question 16

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

Answer 16

Yes

Question 17

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

Answer 17

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

Question 18

How are aquaporin regulated?

Answer 18

Brought to cell surface just like the GLUT transporters

Question 19

What is the cause of nephrogenic diabetes insipidus?

Answer 19

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

Question 20

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

Answer 20

Concentration gradient and voltage

Question 21

What are the three types of gated ion channels?

Answer 21

Voltage gated
Ligand gated
Mechanically gated

Question 22

What is facilitated diffusion?

Answer 22

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

Question 23

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

Answer 23

Higher, duh

Question 24

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?

Answer 24

False–hyperbolic with Vmax.

Question 25

Is transport direction reversible in ion channels?

Answer 25

Yes

Question 26

What is Km for a facilitated ion channel?

Answer 26

[C] at which v =0.5(Vmax)

Question 27

Can facilitated transport transport uncharged substances against their concentration gradient?

Answer 27

No

Question 28

Can facilitated transport transport ions against their electrochemical gradient?

Answer 28

No

Question 29

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

Answer 29

Phosphorylation of glucose to G6P

Question 30

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

Answer 30

Yes, yes, and yes

Question 31

The Na/K pump is used for what?

Answer 31

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

Question 32

What are ABC transporters?

Answer 32

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

Question 33

What type of transporter is the CFTR protein?

Answer 33

Active (ABC family)

Question 34

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

Answer 34

Cystic fibrosis

Question 35

What is the gene that causes NDI?

Answer 35

Mutations in the aquaporin-2 gene

Question 36

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

Answer 36

[C] = get closer to Vmax Km= shifts curve right Transporter = increases Vmax, no change in Km

Question 37

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

Answer 37

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

Question 38

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

Answer 38

Multi-drug resistant proteins. These are ABC trasporters that, when overexpressed, cause clinicially important resistance to CA drug therapy

Question 39

What is an example of antiport?

Answer 39

Movement of Na ions with glucose in the intestines

Question 40

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

Answer 40

co-transport of 1 Na:1K:2Cl from extracellular | fluid to cytosol

Question 41

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

Answer 41

Na/Ca exchanger to pump out Ca Na/H to pump out H and bring in Na

Question 42

True or false: vesicular transport requires energy?

Answer 42

true

Question 43

What type of molecules does vesicular transport?

Answer 43

Large ones

Question 44

What are the three types of vesiicular transport?

Answer 44

1. Phagocytosis 2. Pinocytosis 3. Fluid-phase endocytosis

Question 45

True or false: all cells perform pinocytosis?

Answer 45

True

Question 46

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

Answer 46

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

Question 47

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

Answer 47

Adaptin and clatharin recycled, vesicle ready to fuse

Question 48

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

Answer 48

False- very inefficient

Question 49

What biochemical process is dependent on receptor mediated endocytosis?

Answer 49

LDLs

Question 50

What is caveolae endocytosis?

Answer 50

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).