Lec 2

Question 1

A cell membrane is composed of phospholipids and contains no proteins. This membrane is impermeable to:

1. water
2. ions
3. water and ions
4. the membrane is permeable.

Answer 1

Answer: 3. water and ions.

Question 2

Membrane transport depends on the presence of which type of membrane proteins?

Answer 2

Integral Membrane Proteins

Question 3

Integral Membrane proteins have membrane spanning a-helical domains of how many amino acids?

Answer 3

20 amino acids

Question 4

Integral Membrane Proteins can have multiple membrane spanning domains.

T or F?

Answer 4

True

Question 5

Integral Membrane Proteins cannot be linked to membrane phospholipids.

T or F?

Answer 5

False: They can be linked via oligosaccharide.

Question 6

Integral Membrane Proteins can be linked to fatty acids or prenyl groups.

T or F?

Answer 6

True

Question 7

What type of proteins can be “non-covalently bound with integral proteins” ?

Answer 7

Peripheral Proteins

Question 8

What are the two types of membrane transport?

Answer 8

Active Transport

Passive Transport

Question 9

1. Passive Transport or “Flow” can be acheived through what three types of integral protein transport structures?

Answer 9

1. pores or leak channels
2. channels
3. carriers

Question 10

Which passive transport structure is the fastest?

Which is the slowest?

Answer 10

pres or leak channels - fastest

carriers - slowest

Question 11

Which passive transport structure is never fully open?

Answer 11

carriers - gated by 2 doors that are never open at the same time

Question 12

Which passive transport structure can be closed?

Answer 12

channels - they are gated.

Question 13

Which passive transport structure undergoes simple diffusion, where Net flux = JX ?

Answer 13

pores and channels - have a linear relationship between net flux and ion concentration.

Question 14

Whats the title of the experiment that led to the discovery of transport proteins by injecting a the gene for a protein into a frog ocyte? This led to the swelling and exploding of the ocyte.

Answer 14

The Exploding Cell Assay

Question 15

Which type of transport structure reaches a maximum net influx at an unlimited concentration of ions?

Answer 15

Carriers : creates Carrier Mediated or Facilitated Diffusion.

Question 16

What are the two subcategories of Active Transport?

Answer 16

Primary

Secondary

Question 17

Na+/K+ pump is an example of what subtype of Active Transport?

Answer 17

Primary Active transport

Question 18

In a Na+/K+ Pump, How many ions of each are pumped into the cell membrane, and how many are pumped out?

Na+ = __ pumped in or out?

K+ = __ pumped in or out?

Answer 18

3 Na+ out

2 K+ in

Helps maintain standard gradient of higher K+ inside the cell and higher Na+ outside the cell.

Question 19

What type of secondary active transport structure pumps ions of opposite charge in the same direction?

Answer 19

Cotransporter or Symporter

Question 20

What type of secondary active transport structure pumps ions (with the same charge) in opposite directions?

Answer 20

Exchangers or Antiporters

Question 21

Passive transport is primarily responsible for the maintenance of differences between the concentrations of key ions and is required for resting membrane potential and action potential.

T or F?

Answer 21

False : Active Transport is primarily responsible.

Question 22

What are the two types of secondary active transport structures?

Answer 22

Cotransporter/Symporter

Exchangers/ Antiporters

Question 23

Na+ is about 145 mM inside or outside the cell?

Answer 23

outside

Question 24

K+ is about 120-155 mM inside our outside the cell?

Answer 24

inside

Question 25

Voltage gated ion channels are made up of a single subunit or a pseudo-subunit protein.

T or F?

Answer 25

False - channels are made up of multiple subunits or pseudo-multimeric proteins

Question 26

Voltage gated ions channels are made up of _______ a-helices.

a. hydrophobic
b. hydrophilic
c. amphipathic
d. ionic

Answer 26

amphipathic a-helicies

Question 27

In voltage gated ion channels, the parts of the molecule that face the inside of the “pore” have _____ surfaces.

a. hydrophobic
b. hydrophilic
c. amphipathic
d. none of the above

Answer 27

hydrophilic - to allow passage of charged ions.