Transport across cell membrane

Question 1

What are molecules that pass through the plasma membrane:

Answer 1

Lipid soluble substances + very small molecules ( e.g , CO2, O2, H2O )

Question 2

what are molecules that cannot pass through the plasma membrane

Answer 2

-water soluble (polar) substances
(Sodium ions) and large molecules e.g—> glucose

Question 3

define simple diffusion

Answer 3

net movement of particles from an area of high concentration to an area of low down a concentration gradient

-passive process so no ATP required

Question 4

why does diffusion only take place in liquids and gases

Answer 4

-because they have Kinetic Energy that enables them to constantly move /flow

Question 5

what is needed for molecules to diffuse across the membrane

Answer 5

lipid soluble and small

Question 6

define facilitated diffusion

Answer 6

movement of polar molecules and ions in and out of the cell with the use of carrier and channel proteins

Question 7

what do the protein channels do

Answer 7

form tubes filled with water which enables water-soluble ions to pass through the membrane

Question 8

how do carrier proteins enable a molecule such as glucose to diffuse across the membrane.

Answer 8

-carrier proteins binds to the glucose molecule
-causes a change in shape of the protein
-enables glucose molecule to be released to the other side