Membrane Permeability

Question 1

What kinds of molecules can and cant move freely across the cell membrane and give examples

Answer 1

Can: small hydrophobic molecules, water, glucose (slowly). E.g. Urea, glycerol

Can’t: Charged ions/large molecules

Question 2

Which ATP dependent pump do all cells have?

Answer 2

NaKATPase

Question 3

What is the permeability coefficient and what does a low/high one mean?

Answer 3

How easily something can permeate the membrane - higher coefficient, can cross more easily, lower - membrane less permeable to it.

Question 4

What are the three broad categories of transport of solutes across the membrane?

Answer 4

Diffusion
Facilitated diffusion
Active Transport

Question 5

Passive transport across the membrane is dependent on ___________ and ________________

Answer 5

Permeability

Conc gradient of solute across membrane

Question 6

What is the relationship between rate of diffusion across the membrane and concentration gradient of solute

Answer 6

Linear - increase in rate with increase in conc gradient

Question 7

What are 6 uses of transport of solutes across the membrane?

Answer 7

1) Maintain ionic concentrations
2) Maintain pH
3) Expel waste/toxins
4) Regulation of cell volume (H20 with solutes)
5) Concentration of metabolic fuels and building blocks
6) Generation of ion gradients necessary for electrical excitability of nerves and muscle