Transport

Question 1

3 ways to cross the plasma membrane

Answer 1

Simple diffusion
Passive transport
Active transport

Question 2

Simple diffusion

Answer 2

Small, uncharged molecules or small, polar molecules (less than 90 daltons; water, ethanol, glycerol, etc.)

Question 3

Facilitated diffusion or passive transportation

Answer 3

High conc. to low conc.
Transport mediated or channel mediated
Transport proteins follow Michaelis-Menten equation
Highly specific
Electrochemical gradient can contribute to passage of charged solutes

Question 4

3 types of carrier proteins

Answer 4

Uniport
Symport
Antiport

Question 5

Uniport

Answer 5

Transports one molecule

Question 6

Symport

Answer 6

Transports 2 molecules in the same direction

Question 7

Antiport

Answer 7

Transport 2 molecules in opposite directions

Question 8

Channel proteins

Answer 8

Hydrophilic channels through membrane
Porins (bacteria and mitochondria; large and non-specific)
Aquaporins (rapid influx of water)

Question 9

Ion channels

Answer 9

Specific for specific ions (K, Na, Ca)
Most are gated
Conformation change allows control of passive ion movement

Question 10

Stress gated channel

Answer 10

Venus fly trap: trigger on leaf opens channel that changes turgor pressure- leaf snaps shut
Human ear: sound vibrations tilt hair cells, causing linking filament to pull channel open

Question 11

3 mechanisms for gating ion channels

Answer 11

Voltage gated (changing charge changes conformation)
Ligand gated (binding of molecule changes conformation)
Stress gated (mechanosensitive; pressure opens gate)

Question 12

Energy sources for active transport

Answer 12

Coupled transporter
ATP-driven pump
Light-driven pump (bacteriorhodopsin)

Question 13

Coupled transporter

Answer 13

1 molecule goes with gradient; 1 molecule goes against gradient
Antiport

Question 14

ATP-driven pump

Answer 14

Half of cell’s ATP is used for transport

Question 15

Sodium potassium pump

Answer 15

ATP-driven pump: phosphorylation of the pump causes conformational change
Antiport: transports Na with gradient into cell and K against gradient out of cell
P-type transporter

Question 16

ATP synthase

Answer 16

F-type transporter

Proton gradient causes rotor to turn, producing ATP