Lecture 17 & 18 (Exam 2)

Question 1

Dual roles of a lipid bilayer –

1) A 2D liquid that allows lateral movement of proteins and lipids
2) A _________ barrier

Answer 1

Permeability

Question 2

In _______ transport, no energy is needed and solutes travel down the concentration gradient.

Answer 2

Passive

Question 3

In _______ transport, it is coupled to ATP hydrolysis and solutes travel against the concentration gradient.

Answer 3

Active

Question 4

There are three general modes of transport, which are…

Answer 4

Antiporter
Symporter
Uniporter

Question 5

There are three general categories of transporters –

1) _______ perform primary active transport.
2) _______ traverse the membrane without needing (extra) energy
3) _______ are used in passive transport

Answer 5

Pumps
Carriers
Channels

Question 6

A P-type pump _________ itself.

Answer 6

Phosphorylates

Question 7

This type of pump binds ATP.

Answer 7

ABC transporter (ATP Binding Cassette)

Question 8

This type of pump uses ATP and was first found in yeast vacuoles.

Answer 8

V-type proton pump

Question 9

This type of pump makes ATP (Phosphorylation factor).

Answer 9

F-type ATP synthase

Question 10

In P-type ATPases which use primary active transport, one type is _____ potassium move into the cytosol and ______ sodium move to the outside. Their role is electrical excitation (neurons, muscles), gradient driving active transport.

Answer 10

2

3

Question 11

Another type of P-type ATPase is when 2 ________ move out to the sarcoplasmic reticulum. This is at the muscle.

Answer 11

Calcium

Question 12

Another type of P-type ATPase is when 1 _______ moves to the cytosol and 1 _______ moves to the stomach. The location is the stomach and its role is digestion/gastric pH.

Answer 12

K+

H+

Question 13

In a P-type pump, there are 4 domains. This domain spans the lipid bilayer.

Answer 13

Transmembrane domain

Question 14

In a P-type pump, there are 4 domains. This domain links the cytosolic domains to the transmembrane domain.

Answer 14

A/Actuator domain

Question 15

In a P-type pump, there are 4 domains. This domain binds ATP.

Answer 15

N/Nucleotide binding domain

Question 16

In a P-type pump, there are 4 domains. This domain accepts the phosphate from ATP.

Answer 16

P/Phosphorylation domain

Question 17

An example of a P-type pump is SERCA. Put the following steps in order –

A. Release of Pi 
B. ATP binds, Ca++ ions trapped 
C. Eversion to E2, Ca++ ions released 
D. E1, unphosphorylated, Ca++ ions bound 
E. ATP hydrolysis, self phosphorylation
F. Eversion to E1

Answer 17

1. D
2. B
3. E
4. C
5. A
6. F

Question 18

In pumps, E1 state means it’s open to the (OUTSIDE/INSIDE) and E2 state means it’s open to the (OUTSIDE/INSIDE).

Answer 18

Inside

Outside

Question 19

Another example of P-type ATPase pumps are Na/K pump. Put the following steps in order —

A. Eversion to E1
B. ATP hydrolysis, self phosphorylation 
C. Binding of K+
D. Na+ ions trapped
E. K+ ions trapped, release of Pi, ATP rebinding 
F. Release of K+
G. E1, Na+ ions bound, ATP bound
H. Eversion to E2, Na++ ions released

Answer 19

1. G
2. D
3. B
4. H
5. C
6. E
7. A
8. F

Question 20

_______ and _______ both lock the Na/K pump in the E2 conformation. It keeps Na+ inside the cell, and excess Na+ is removed by exchanging with Ca++. Extra Ca++ then makes the heart contract.

Answer 20

Digitalis

Ouabain

Question 21

Two examples of ABC transporters are ______ protein, which is a monomer, and ______, which is a homodimer.

Answer 21

MDR

MsbA

Question 22

Put the following steps of the ABC transporter in order –

A. Small molecule is released

B. Small molecule binds and is trapped; ATP binding site affinity increases

C. Empty transporter

D. ATP hydrolysis and release

E. 2 ATPs bind causing eversion

Answer 22

1. C
2. B
3. E
4. A
5. D

Question 23

This type of active transport occurs after primary active transport creates a gradient, then a passive channel or carrier allows ions/molecules to fall back down the gradient with a high value stowaway.

Answer 23

Secondary active transport

Question 24

What is an example of secondary active transport?

Answer 24

Na-Glucose transport

Lactose permease

Question 25

By definition, all secondary transporters are ________.

Answer 25

Symporters

Question 26

An example of secondary active transport is lactose permease. Put the following steps in order —

A. Eversion (1)
B. Eversion (2)
C. Deprotonation
D. Lactose binds
E. Lactose released 
F. Empty carrier, H+ binds and increases affinity for lactose

Answer 26

1. F
2. D
3. A
4. E
5. C
6. B

Question 27

In simple diffusion, a factor affecting diffusion rate is the magnitude of the concentration gradient. Larger = ________.

Answer 27

Faster

Question 28

In simple diffusion, a factor affecting diffusion rate is the size of the molecule. Larger = _______.

Answer 28

Slower

Question 29

In simple diffusion, a factor affecting diffusion rate is the surface area: volume ratio (shape). Higher = _______.

Answer 29

Faster

Question 30

In simple diffusion, a factor affecting diffusion rate is the temperature. Higher = _______.

Answer 30

Faster

Question 31

In simple diffusion, a factor affecting diffusion rate is the density of the solvent. Higher = _______.

Answer 31

Slower

Question 32

In simple diffusion, a factor affecting diffusion rate is the solubility of solute. Non polar = ________.

Answer 32

Soluble

Question 33

In simple diffusion, a factor affecting diffusion rate is the distance to the destination. Longer = _______.

Answer 33

Slower

Question 34

A type of passive transport is facilitated diffusion, which uses ion channels. It has 2 important pieces, which are…

Answer 34

1. Selectivity filter

2. Gate

Question 35

What are the 3 ways to gate a channel?

Answer 35

Voltage
Ligand
Stress

Question 36

5 ion channels work together to contract your muscles:

1. Depolarization opens _______-gated Ca++ channels
2. Exocytosed acetylcholine opens _______-gated Na+ channels
3. Local depolarization opens adjacent _______-gated Na+ channels
4. As the depolarization spreads, _______-gated Ca++ channels open
5. _______ Ca++ release channels embedded in the SR open

Answer 36

Voltage
Ligand
Voltage
Voltage
Couple 

***Study Slide 25

Question 37

This example of a facilitated diffusion channel is always open and is a physical connection between the two cells. It allows cytoplasm sharing and no specificity filter.

Answer 37

Gap junctions

Question 38

This example of a facilitated diffusion channel is always open and only lets water (polar) but not ions through. Ions would be very repelled.

Answer 38

Aquaporins