Lecture 17/18 Transport Through Membranes

Question 1

What are the features of passive transport?

Answer 1

No energy needed.

Solute travels down concentration gradient

Question 2

What are the features of active transport?

Answer 2

Coupled to ATP hydrolysis

Solute travels against concentration gradient.

Question 3

______ perform primary active transport?

Answer 3

Pumps

Question 4

______ Transverse the membrane without needing extra energy

Answer 4

Carriers

Question 5

_____ are used in passive transport?

Answer 5

Channels

Question 6

What are the 4 domains of P-type ATPases?

Answer 6

1. Transmembrane domain
2. A/Actuator domain
3. N/Nucleotide binding domain
4. P/phosphorylation domain

Question 7

What are the two examples of P-type ATPases given?

Answer 7

SERCA + Na/K pump (3:2 ratio)

Question 8

What are the two examples of ABC transporters given?

Answer 8

MDR protein + MsbA

Question 9

What is the function of ABC transporters?

Answer 9

Transporting small molecules from one side of the membrane to the other, or from one side of the transporter to the other using ATP.

Question 10

Na-Glucose cotransport is an example of what?

Answer 10

Secondary active transport.

Question 11

How does secondary active transport work?

Answer 11

After primary active transport creates a charged gradient, other molecules can follow the charge into or out of a molecule.

Question 12

Secondary transporters can be antiporters? T/F

Answer 12

False, they have to be symporters

Question 13

What are the seven factors affecting diffusion rates?

Answer 13

Magnitude of concentration gradient 
Size of the molecule
Surface area: volume ratio
Temperature
Density of solvent
Solubility of solute (nonpolar = soluble)
Distance to destination

Question 14

What are the two important features to Ion channels/

Answer 14

Selectivity filter

Gate

Question 15

What are the three ways to gate an ion channel?

Answer 15

Voltage
Ligand
Stress

Question 16

What 5 ion channels must work together in order to contract muscles? What are the steps?

Answer 16

1. Depolarization opens voltage-gated calcium channels
2. Exocytosed acetylcholine opens ligand-gated Sodium Channels
3. Local depolarization opens adjacent voltage-gated sodium channels
4. as the depolarization spreads, voltage gated calcium channels open
5. coupled calcium-release channels embedded in the SR open.

Question 17

What are the two examples of facilitated diffusion channels given in the lecture?

Answer 17

Gap Junctions - allow cytoplasm sharing

Aquaporins - let water but not ions through