2: Membranes, Solutes, Diffusion, and Transport

Question 1

Where is potassium concentration high?

Answer 1

intracellular fluid

Question 2

Where is sodium concentration high?

Answer 2

extracellular fluid

Question 3

Where is chlorine concentration high?

Answer 3

extracellular fluid

Question 4

How does membrane surface area affect simple diffusion?

Answer 4

increased membrane surface area, increased diffusion rate

Question 5

How does the diffusion coefficient affect diffusion?

Answer 5

increased diffusion coefficient, increased diffusion rate

Question 6

How does concentration differences affect simple diffusion?

Answer 6

increased concentration difference increased diffusion rate

Question 7

How does membrane thickness affect simple diffusion?

Answer 7

increased membrane thickness decreases diffusion rate

Question 8

What is the driving force for solute flux?

Answer 8

concentration difference

Question 9

Ionized molecules diffuse ____ than un-ionized molecules

Answer 9

slower

Question 10

Smaller molecules diffuse ____ than larger molecules

Answer 10

faster

Question 11

Lipid-soluble molecules diffuse ____ than water-soluble molecules

Answer 11

faster

Question 12

Do gases such as CO2 and O2 diffuse across the plasma membrane?

Answer 12

yes

Question 13

Do hydrophobic molecules such as benzene diffuse across the plasma membrane?

Answer 13

yes

Question 14

Do small polar molecules such as H2O and ethanol diffuse across the plasma membrane?

Answer 14

yes

Question 15

Do large polar molecules such as glucose diffuse across the plasma membrane?

Answer 15

no

Question 16

Do charged molecules such as ions diffuse across the plasma membrane?

Answer 16

no

Question 17

Do amino acids diffuse across the plasma membrane?

Answer 17

no

Question 18

What is the oil/water partition coefficient (K)?

Answer 18

a measure of a solute’s solubility in water or lipids

Question 19

K > 1

Answer 19

fats and sterols, lipophilic, can cross quickly

Question 20

K < 1

Answer 20

ionized solutes, hydrophilic, hard to cross membrane

Question 21

K equation

Answer 21

equilibrium concentration of solute in oil / equilibrium concentration of solute in water

Question 22

What plays an important role in charge movement and transmembrane potential (neuron excitability)?

Answer 22

K+ leak channels

Question 23

Facilitated diffusion pros

Answer 23

can be faster than simple diffusion when at lower concentrations

Question 24

Facilitated diffusion cons

Answer 24

saturable

Question 25

Simple diffusion pros

Answer 25

not saturable

Question 26

Simple diffusion cons

Answer 26

slower at lower concentrations

Question 27

T/F: Facilitated diffusion transporters display substrate stereoselectivity

Answer 27

T

Question 28

What inhibits ATPase activity?

Answer 28

digitalis

Question 29

What ions are pumped by ATPase?

Answer 29

3 Na+ and 2 K+

Question 30

What charge occurs on the extracellular side after ATPase pumps ions?

Answer 30

positive

Question 31

Liver transporters

Answer 31

move drugs into and out of hepatocytes and into bile or bloodstream

Question 32

H, K-ATPase

Answer 32

forms gastric acid in stomach

Question 33

P-glycoprotein

Answer 33

actively moves xenobiotics out of cells and from the brain and into the bloodstream

Question 34

MDR1

Answer 34

multi-drug resistant 1

Question 35

What does a mutation in MDR1 cause?

Answer 35

P-glycoprotein defect limiting transporter activity