Membrane Transport

Question 1

What are the two properties that influence whether a particle can permeate the plasma membrane without assistance?

Answer 1

solubility and size of particle

Question 2

What factors influence the rate of net of diffusion across the membrane and collectively make up Fick’s law of diffusion?

Answer 2

• The magnitude of the concentration gradient.
• The surface area of the membrane across which diffusion is taking place.
• The lipid solubility of the substance.
• The molecular weight of the substance.
• The distance through which diffusion must take place.

Question 3

Do cations tend to move toward more negatively or positively charged ions?

Answer 3

negatively

Question 4

What are aquaporins?

Answer 4

water channels

Question 5

What is osmolarity?

Answer 5

the concentration of osmotically active particles present in a solution

Question 6

What is tonicity?

Answer 6

effect a solution has on cell volume

Question 7

What is isotonic saline and what can it be used for?

Answer 7

0.9% NaCl solution, used as vehicle for IV drug delivery

Question 8

What is carrier mediated transport?

Answer 8

A substance binds onto a specific carrier which undergoes a conformational change (shape change) which transports the substance

Question 9

What three important characteristics determine the kind and amount of material transferred across the membrane?

Answer 9

Specificity
Saturation
Competition

Question 10

What are the two forms of carrier mediated transport?

Answer 10

Facilitated diffusion (not requiring energy)
Active transport (requiring energy)

Question 11

What is primary active transport?

Answer 11

Energy is directly required to move a substance against its concentration gradient

Question 12

What is secondary active transport?

Answer 12

The transfer of a solute across the membrane is always coupled with the transfer of the ion that supplies the driving force (typically Na+)

Question 13

In what cells is the Na+-K+ ATPase pump found?

Answer 13

all

Question 14

What does Na+-K+ ATPase pump do?

Answer 14

• Helps establish Na+ and K+ concentration gradients across the plasma membrane
• Helps regulate cell volume by controlling concentration of solutes inside the cell.
• The energy used to drive the pump indirectly serves as the energy source for secondary active transport

Question 15

What are the 2 types of secondary active transport and what is the difference between them?

Answer 15

Symport
-The solute and Na+ move in the same direction
Antiport
-The solute and Na+ move in opposite directions (Na+ into, solute out of the cell).

Question 16

Is this symport or antiport: glucose absorption at the apical membrane of enterocytes?

Answer 16

symport

Question 17

Is this symport or antiport: cells exchange Na+ and H+?

Answer 17

antiport

Question 18

Does vesicular transport require energy?

Answer 18

Yes

Question 19

What is a way of adding carriers, channels or receptors to the plasma membrane (E.g. GLUT4 & insulin)?

Answer 19

exocytosis