Transport

Question 1

What diffuses across the membrane?

Answer 1

-small nonpolar molecules
-gases
-steroids

Question 2

What doesn’t diffuse across the membrane?

Answer 2

-ions
-polar molecules
-large macromolecules
-water
-glucose (technically does, but very, very slowly)

Question 3

Passive Transport

Answer 3

-Moves things across the concentration gradient
-Simple Diffusion —> stuff like gases and steroids moves across the phospholipid membrane
-Facilitated Diffusion —> carrier and channel proteins help to transport things like water (in the case of water, aquaporins are used) across the cell membrane

Question 4

Active Transport

Answer 4

-Electrogenic pumps, like those in the case of Na+/K+, which use ATP to push positive charge out of the cell
-Endocytosis, which includes phagocytosis (which brings in food), pinocytosis (which brings in liquids), and receptor-mediated transport (which uses Y-shaped receptors to pull things into the cell)