L2 Membrane Transport

Question 1

What forces drive solutes from one side of membrane to the other?

Answer 1

Concentration gradients

Ion/electrical gradients

Question 2

Electrochemical gradient is?

Answer 2

Concentration gradient and electrical gradient combined

Question 3

What solute properties dictate its permeability?

Answer 3

Hydrophobicity (nonpolar)
Size
Charge
Polarity

Question 4

Which molecules do not passively cross?

Answer 4

Large uncharged polar
And
Ions

Question 5

Passive(simple) diffusion v. passive Carrier-mediated transport

Answer 5

Neither require energy

Simple diffusion does not require channel or transporter while carrier-mediated does

Question 6

Passive carrier-mediated v. active carried-mediated

Answer 6

Active requires energy (ATP directly or indirectly) and moves against concentration gradient

Question 7

Primary active carrier mediated v. Secondary active carrier mediated

Answer 7

Primary uses ATP hydrolysis directly

Secondary uses energy of an ions electrochemical gradient

Both are against conc gradient, they use energy to drive conformation change in carrier

Question 8

In active transport, what’s the carriers affinity for the solute on the side of the membrane where the solute concentration is low?

Answer 8

It’s a high affinity binding site

Question 9

In active transport, what’s the carriers affinity for the solute on the side of the membrane where the solute concentration is high?

Answer 9

It’s a low affinity bonding site

Allows solute to dissociate despite the high solute concentration

Question 10

Secondary active transport is also called

Answer 10

Coupled transport because solutes are transported simultaneously

Ex. Active transport of glucose (glucose moves against its conc gradient through Na+ moving with its conc gradient to form a ion gradient)

Must be symport or antiport

Question 11

Primary active transports

Answer 11

ATP hydrolysis driven pump

Many different types

Ex. Na+/K+ ATPase

Question 12

Channels are?

Answer 12

Transmembrane proteins that form aqueous pores through hydrophobic membrane

Mostly commonly transport ions

Selective but no true binding site

Gated

Question 13

Types of gated channels

3

Answer 13

Voltage gated
Ligand gated
Mechanically gated

Question 14

Voltage gated channel

Answer 14

Charge opens or closes channel

Question 15

Ligand gated channel

Ex. Acetylcholine

Answer 15

Acetylcholine binds, triggers conformation change, channel opens and ion flow through

Question 16

Mechanically gated

Answer 16

Opens by physical distortion of cell membrane

Question 17

Uniport

Answer 17

Transmembrane movement of a single molecule

Question 18

Symport

Answer 18

Simultaneous transmembrane movement of two molecules in same direction

Coupled

Question 19

Antiport

Answer 19

Simultaneous transmembrane movement of two molecules in opposite direction

Couple

Question 20

Can a channel protein or a carrier protein transport faster?

Answer 20

Channel

Up to 1000x faster

Carries can become saturated