Cell Membranes

Question 1

What is the function of membranes?

Answer 1

selectively permeable: controls what enters + exits cell
separate compartment from cytoplasm: specific metabolic reactions take place within them
internal transport system
isolate enzymes that might damage cell e.g lysosomes
provides surface on which reactions can occur

Question 2

What is the membrane made up of?

Answer 2

phospholipid

Question 3

how is the membrane arranged?

Answer 3

in a bilayer
hydrophilic heads on outside and hydrophobic tails on inside

Question 4

why is it arranged this way?

Answer 4

in an aq environment
hydrophilic head
hydrophobic tail

Question 5

What is the purpose of a phospholipid?

Answer 5

forms water impermeable barrier to polar substances
permeable to allow non-polar molecules to pass through
allows cells to maintain different conc. either side
makes membrane fluid (can fuse with others)
gives flexibility and fluidity

Question 6

What passes through cell membrane?

Answer 6

small
uncharged
non polar

Question 7

What uses protein channel to pass through cell membrane?

Answer 7

large
uncharged
polar

Question 8

Why is it named a fluid mosaic model?

Answer 8

fluid: molecules move around
mosaic: made up of different sorts of molecules = proteins and phospholipids

Question 9

what happens if there is too much cholesterol or to little?

Answer 9

too much: too rigid
too little: too fluid

Question 10

What is the function of a glycoprotein/glycolipid?

Answer 10

acts as cell recognition site

Question 11

What is the function of cholesterol?

Answer 11

reduce lateral movement of other molecules
make membranes less fluid at high temperatures