Chapter 13

Question 1

Pumps

Answer 1

Use ATP (or light) to drive the thermodynamically unfavorable movement of ions or molecules (against a concentration gradient)

Question 2

What process do pumps use

Answer 2

primary active transport

Question 3

Carriers (aka transporters)

Answer 3

Transport an ion or molecule across a membrane, but without ATP, by pushing one molecule with another

Question 4

What process do Carriers (aka transporters) use

Answer 4

secondary active transport

Question 5

Channels

Answer 5

pores that allow ions to move rapidly through a membrane down a concentration gradient

Question 6

Rate of movement through channel depends on

Answer 6

size of gradient differential

Question 7

Channels can be gated by

Answer 7

certain ligands or membrane voltage

Question 8

gated

Answer 8

opened

Question 9

gap-junction

Answer 9

a channel between two cells; common in muscle-cell concentraction

Question 10

What factors determine if a molecule will cross the membrane

Answer 10

-Is it Permeable to the membrane?
-Availability of an energy source.

Question 11

Free energy stored in conc. gradients

Answer 11

∆𝐺=∆𝐺^0′+𝑅𝑇𝑙𝑛(𝑐2/𝑐1 )

Question 12

Free energy stored in conc. gradients with charged molecules

Answer 12

∆𝐺=𝑅𝑇𝑙𝑛(𝑐_2/𝑐_1 )+𝒵ℱ∆𝑉

Question 13

P-type ATPases

Answer 13

use a phosphorylaspartate intermediate to change the pump’s structure

Question 14

How many P-type ATPases do humans have

Answer 14

70

Question 15

Pumps that use ATP

Answer 15

1. Na+-K+ ATPase
2. Ca2+ ATPase
3. H+-K+ ATPase

Question 16

Na+-K+ ATPase

Answer 16

inhibited by ouabain

Question 17

Ca2+ ATPase

Answer 17

Ca2+ sequestration in SR after muscle contraction

Question 18

H+-K+ ATPase

Answer 18

gastric acid pump

Question 19

P-type ATPases rely on

Answer 19

phosphorylaspartate intermediate

Question 20

primary active transport

Answer 20

ATP is “burned” in order to transport something directly across the membrane

Question 21

Most often primary active transport is used to transport ions such as

Answer 21

calcium, sodium, potassium, chloride, or protons

Question 22

ABC transporters use

Answer 22

ATP-binding to drive eversion

Question 23

MDR or P-glycoprotein

Answer 23

eukaryotic multidrug resistance protein that “kicks out” compounds of a certain size

Question 24

homo-dimers (such as MsbA)

Answer 24

change shape but maintain the same stoichometry

Question 25

E. coli contains ____ different types of ABC transporters

Answer 25

79

Question 26

Humans contains ___ different types of ABC transporters

Answer 26

over 150

Question 27

CFTR

Answer 27

ABC transporter that transports a chloride

Question 28

Defective CFTR genes lead to

Answer 28

cystic fibrosis

Question 29

Eukaryotic ABC transporters are almost always

Answer 29

exporters

Question 30

Are channels faster than pumps and transporters

Answer 30

Yes; 1000x faster

Question 31

Antiport

Answer 31

two things are moving in opposite directions

Question 32

Symport

Answer 32

two things are moving in same direction

Question 33

Uniport carrier (facilitated diffusion)

Answer 33

moves a molecule down a concentration gradient in either direction with no secondary molecule and no movement against gradient

Question 34

facilitated diffusion used in transporting

Answer 34

polar molecules like sugars

Question 35

Lactose permease of E. coli is

Answer 35

H+ symporter

Question 36

Lactose permease (LacY) uses

Answer 36

H+ gradient generated by the bacterial electron transport chain to power the import of lactose

Question 37

LacY mechanism

Answer 37

binding of a proton to a specific Glu residue and then a lactose

Question 38

A patch-clamp measures

Answer 38

activity of ion channels

Question 39

Tetrodotoxin

Answer 39

from puffer fish that blocks sodium channels in neurons

Question 40

What was used to purify first Na+ channel

Answer 40

Tetrodotoxin was used on electric eel by affinity chromatography

Question 41

Na+, Ca2+, and K+ channels have a _____ structure

Answer 41

conserved tetrameric

Question 42

K+ ions interact with 8 carbonyl oxygens to

Answer 42

power its desolvation

Question 43

Why can K+ not pass through a Na+ channel?

Answer 43

K+ ion is too big

Question 44

How do K+ channels stop Na+ from going through?

Answer 44

K+ ions are large enough to engage the carbonyls on both sides of that narrow channel. Na+ are not.

Question 45

How do K+ ions move through channel

Answer 45

K+ ions have to "climb an energy ladder" by shedding its water at a specific part of the pore and interacts with a conserved sequence of amino acids that is found in the K+ channel

Question 46

Hydration energies increases as

Answer 46

atoms become smaller in size

Question 47

the rate of conformational change to close the open channel is too slow so

Answer 47

so the inactivation ball evolved to do this faster

Question 48

α-Cobratoxin

Answer 48

 nicotinic acetylcholine receptor (nAChR) antagonist which causes paralysis by preventing the binding of acetylcholine to the nAChR.

Question 49

the best characterized ligand-gated (Na+/K+) channel

Answer 49

The acetylcholine receptor

Question 50

Acetylcholinesterase

Answer 50

normally hydrolyzes acetylcholine very rapidly, so that the response lasts only about a millisecond

Question 51

Acetylcholinesterase is anchored to

Answer 51

postsynaptic membrane by a glycolipid "tether (NOT part of receptor)

Question 52

Where does the nerve-cell’s resting membrane potential come from?

Answer 52

leakage in channel opens and allowing ions to exit cell

Question 53

Which channel is the fastest inactivate

Answer 53

Na+ is fastest; K+ open and close late