structure of a cell membrane

Question 1

what type of molecules can pass through a cell membrane

Answer 1

small
non polar
lipid soluble

Question 2

describe the phospholipid bilayer

Answer 2

there are two layers of phospholipids
there tails face inwards as they are hydrophobic and so they are protected and water soluble substances cannot pass
the hydrophilic heads face outwards

Question 3

cholesterol in a membrane

Answer 3

provides structure and prevents fluidity

Question 4

proteins in a membrane

Answer 4

Integral - these are found on both sides of the membrane
examples are channel and carrier proteins which transport large molecules and ions

peripheral - found on just one side of the membrane
they are used for structure and cell signalling

Question 5

glycoproteins and glycolipids in a membrane

Answer 5

attachement of cells
cell recognition
communication between cells

Question 6

how does temperature affect a membrane when it is below 0 degrees

Answer 6

the phospholipids are tightly packed and the channel and carrier proteins will denature increasing the permeability of the membrane
ice crystals may also form increasing permeability even further

Question 7

how does the temperature affect a membrane when it is between 0-45 degrees

Answer 7

the membrane is fluid and can move freely

Question 8

how does the temperature affect the membrane when it is above 45 degrees

Answer 8

the phospholipids will melt increasing its permeability
the channel and carrier proteins will denature further increasing permeability

Question 9

explain how solvents pass a membrane, like an ethanol molecule

Answer 9

they bind to the membrane forming hydrogen bonds which increases the permeability as the placement is disrupted, allowing the molecules past