Lecture 18 - Txpt I Flashcards Preview

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Flashcards in Lecture 18 - Txpt I Deck (29):
1

What specific non-covalent interaction forms plasma membranes?

Hydrophobic

2

What is meant by "specificity" of membrane channel proteins?

Membrane proteins will only transport specific molecules across te plasma membrane

3

A protein with several transmembrane domains.

Polytopic

4

The plasma membrane is ______ to lipophilic molecules.

Permeable

5

The membrane is ______ to hydrophilic molecules.

impermeable

6

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

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

7

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

By changing the expression

8

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

passive

9

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

Active transport

10

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

Facilitated diffusion

11

Explain how free energy is generated by ATP pumps.

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

12

When is free energy across a membrane = 0mV?

When Co=Ci

13

Free E* calculation for a charged molecule

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

14

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

Aspartate

15

Describe the MOA of digoxin

Answer:

16

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

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

17

What is the purpose of calmodulin in the PMCA?

Calmodulin binds to ______

18

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

Non-covalent

19

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

ATP hydrolysis that occurs after ATP binding/substrate release

20

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

2* active

21

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

2* active

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

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.

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

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.

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

C. Binding of substrate/drug

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

B. Binding of ATP

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

A. Hydrolysis of ATP

25

P-type ATPases are called "P-type" for what reason?

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

26

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

C. Aspartate

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

D. ATP hydrolysis