Chapter 13 : Membrane Transport

Question 1

Membranes are impermeable to

Answer 1

ions and polar molecules

Question 2

Cells use membrane proteins to

Answer 2

transport ions and molecules across the membrane

Question 3

What are the two types of cellular transport ?

Answer 3

Active and passive

Question 4

Passive Transport

Answer 4

Uses no energy and moves molecules from an area of high concentration to low concentration

Question 5

Active Transport

Answer 5

Uses energy to move molecules from an area of low concentration to high concentration

Question 6

Types of passive diffusion

Answer 6

Simple diffusion and facilitated diffusion

Question 7

Simple diffusion

Answer 7

Molecules that move across the membrane without use of energy

Question 8

Facilitated Diffusion

Answer 8

Molecules that move across the membrane with the aid of a membrane protein

Question 9

What kind of curve does facilitated diffusion have

Answer 9

A logarithmic curve

Question 10

What kind of curve does simple diffusion have

Answer 10

A linear curve

Question 11

Channel proteins are used in

Answer 11

facilitated diffusion

Question 12

Channel proteins can be used to transport ions such as

Answer 12

Na K, Mg , H20 , glycerol etc

Question 13

Selectivity filter

Answer 13

A group of amino acid acid residues that select and bind to specific molecules

Question 14

What does it mean if a channel is gated

Answer 14

A signal induces a conformational change to open a channel through ligand binding or a voltage change

Question 15

Why are ion channels so important in the nervous system

Answer 15

They help to transport K and Na with electrical signals in serve cells

Question 16

What are two essential structures of K+ channels

Answer 16

• A selectivity filter

- A gate that opens and closes

Question 17

KcsA channel

Answer 17

channel found in Streptococcus lividans

• contains 3 α-helices
• gated by intracellular pH

Question 18

What is the sequence of pentapeptides found in KcsA

Answer 18

TVGYG

Question 19

What is the purpose of the KcsA backbone ?

Answer 19

the oxygens dehydrate the K+ ions by replacing the bonding with water with oxygen instead

Question 20

Why is the K+ channel very selective for K+ over Na + ?

Answer 20

The smaller Na molecules cannot bind as favorably with oxygens

Question 21

For every 2 K+ ions, how many Na+ ions are transported ?

Answer 21

3

Question 22

By changing the selectivity filter , you can also change the

Answer 22

ions selected for transport.

Ex) substituting aspartic acid for tyrosine can change ion selectivity

Question 23

How many helix segments are in a voltage gated K channel

Answer 23

4 , They serve as voltage sensors

Question 24

When the paddles of a K channel lie in the down position , the channel is

Answer 24

closed

Question 25

When the paddles on the K channel lie in the up position , the channel is

Answer 25

open , from depolarization

Question 26

The ball and chain model has been used to describe which voltage gated channel ?

Answer 26

K+ and Na+

Question 27

What are some of the kinds of gates that open channels ?

Answer 27

ligand, voltage, pH gated

Question 28

What is the most common forms of energy input in active transport ?

Answer 28

• ATP hydrolysis
• light energy
• ion gradients

Question 29

How do ATPases provide energy

Answer 29

Through coupled phosphoylation

Question 30

Examples of secondary transport molecules

Answer 30

Lactose or permease which can be used as energy

Question 31

All cells expel ___ ions and uptake ____ ions

Answer 31

Na + ions are expelled and K+ ions are uptaken

Question 32

ATPase is used as a ___ to transport sodium and potassium

Answer 32

pump

Question 33

The sodium ATPase can be inhibited by

Answer 33

cardiac glycosides

Question 34

Examples of cardiac glycosides

Answer 34

oubain and digitalis .

Both can help to treat CHF but are poisonous at high amounts

Question 35

The Ca2+ ATPase is primarily found in which types of cells ?

Answer 35

muscle cells

Question 36

An enzyme that uses light instead of ATP as energy source

Answer 36

bactiorhodopsin

Question 37

Gastric H+ or K+ ATPase enzymes are found primarily in

Answer 37

the stomach

Question 38

How does phosphorylation play a role in the function of the Na+ K+ ATPase ?

Answer 38

Phosphorylation of a protein adds a large negative charge to it which changes the shape and affinity for the substrate when converting

Question 39

What other kinds of energy besides ATP do proteins use to actively transport molecules ?

Answer 39

Concentration gradient, electrical gradient,light