Lecture 18 - Txpt I

Question 1

What specific non-covalent interaction forms plasma membranes?

Answer 1

Hydrophobic

Question 2

What is meant by “specificity” of membrane channel proteins?

Answer 2

Membrane proteins will only transport specific molecules across te plasma membrane

Question 3

A protein with several transmembrane domains.

Answer 3

Polytopic

Question 4

The plasma membrane is ______ to lipophilic molecules.

Answer 4

Permeable

Question 5

The membrane is ______ to hydrophilic molecules.

Answer 5

impermeable

Question 6

Explain how transport specificity is important in regulation of biochemical processes.

Answer 6

Since transport proteins are specific, only those transporters who are expressed can be regulators of biochemical processes. Ex: a lack of GLUT-1 expression can lead to increased blood glucose levels

Question 7

Metabolism can be regulated by what mechanism relating to transport proteins?

Answer 7

By changing the expression

Question 8

Transport in which a molecule is moved down its natural [gradient]

Answer 8

passive

Question 9

Transport by which a molecule is moved against its [gradient], a process which requires E*

Answer 9

Active transport

Question 10

What type of passive transport requires a channel/carrier protein?

Answer 10

Facilitated diffusion

Question 11

Explain how free energy is generated by ATP pumps.

Answer 11

ATP pumps utilize ATP to pump ions against their [gradient]. As a result, a greater [gradient] is formed, which causes more free E*

Question 12

When is free energy across a membrane = 0mV?

Answer 12

When Co=Ci

Question 13

Free E* calculation for a charged molecule

Answer 13

DeltaG=(2.3)(RT)log([C2]/[C1])+ (z)(F)(deltaV)

Question 14

Phosphorylation of a p-type ATPase occurs on what amino acid?

Answer 14

Aspartate

Question 15

Describe the MOA of digoxin

Answer 15

Answer:

Question 16

F(x) of the plasma membrane calcium ATPase (PMCA)

Answer 16

To maintain high extracellular [Ca2+] by pumping Ca2+ out of the cell.

Question 17

What is the purpose of calmodulin in the PMCA?

Answer 17

Calmodulin binds to ______

Question 18

(Covalent/non-covalent) forces guide the formation of plasma membranes.

Answer 18

Non-covalent

Question 19

What resets the ABC transporter to its original state, where it is able to again bind substrate?

Answer 19

ATP hydrolysis that occurs after ATP binding/substrate release

Question 20

Lactos permease uses a proton gradient generated by fuel oxidation to move lactose against its [gradient]. This is an example of _____ transport.

Answer 20

2* active

Question 21

Lactos permease uses a proton gradient generated by fuel oxidation to move lactose against its [gradient]. This is an example of _____ transport.

Answer 21

2* active

Question 22

Na/K/ATPase pumps are affected by digitoxigenin ("Digoxin") and oubabain. When exposed to these drugs, Na/K/ATPase pumps remain phosphorylated in the \_\_\_\_ stage. 
A. Empty
B. E1P
C. E2P
D. Na+ bounds

Answer 22

C. E2P - Digoxin prevents the dephosphorylation of the enzyme, “locking” it into the E2P state, which produces a decrease in the Na/Ca Exchanger activity. This increases cytosolic [Ca2+], increasing force of contraction.

Question 23

Plasma Membrane Calcium ATPase (or "PMCA" for short) is used to transport Ca2+ from the cytosol to the extracellular fluid. The PMCA is stimulated by the binding of what chemical?
A. Calcium
B. Calmodulin
C. Calsequestrin
D. Calcitriol

Answer 23

B. Calmodulin (CaM); CaM binds to Ca2+, and the entire complex then binds to the PMCA. This induces ATP cleavage and Ca2+ is pumped out of the cell.

Question 23

ABC transporters are important in the development of multi-drug resistance (MDR) in pathogenic bacteria. What produces the initial change in conformation to the ABC transporter?
A. ATP hydrolysis
B. Binding of ATP
C. Binding of substrate/drug
D. Ejection of bound ATP

Answer 23

C. Binding of substrate/drug

Question 23

ABC transporters are important in the development of multi-drug resistance (MDR) in pathogenic bacteria.
What produces the conformational change that “expels” the drug from the bacterial interior?
A. Binding of substrate
B. Binding of ATP
C. Hydrolysis of ATP
D. Formation of the Enzyme-substrate complex

Answer 23

B. Binding of ATP

Question 24

ABC transporters are important in the development of multi-drug resistance (MDR) in pathogenic bacteria. What returns the transporter to the original state, where it is ready to bind to another drug?
A. Hydrolysis of ATP
B. Binding of new substrate/drug
C. Binding of ATP
D. Expulsion of the drug

Answer 24

A. Hydrolysis of ATP

Question 25

P-type ATPases are called “P-type” for what reason?

Answer 25

After cleavage of ATP, the Pi is bound to the enzyme to form an E-P intermediate

Question 26

Phosphorylation of the enzyme occurs at what residue in P-type ATPases?
A. Tyrosine
B. Serine
C. Aspartate
D. Arginine

Answer 26

C. Aspartate

Question 26

This changes the conformation of P-type ATPases to expel the substrate.
A. Expulsion of substrate
B. Binding of substrate
C. ATP binding
D. ATP hydrolysis

Answer 26

D. ATP hydrolysis