Cell Membrane Structure 2B

Question 1

What do membranes do

Answer 1

Control what enters and leave cells barrier between cells and their environment
Partially/ selectively permeable

Question 2

Fluid mosaic membrane

Answer 2

Phospholipid bilayer - double bilayer
Fluid - phospholipids constantly moving
Mosaic - different types of proteins are scattered throughout the bilayer

Question 3

what is a glycoprotein

Answer 3

a protein with a carbohydrate molecule attached

Question 4

what is a glycolipid

Answer 4

a lipid with a carbohydrate molecule attached

Question 5

Role of cholesterol in cell membranes

Answer 5

fit between the phospholipids bind to hydrophobic tails causing them to pack more tightly together restricts movement of the phospholipid keeping it less fluid and more rigid

Question 6

Phospholipid structure

Answer 6

Hydrophobic head
Hydrophilic tail
Heads face out, tails face in
Centre is hydrophobic acts as a barrier to dissolved substances

Question 7

Membrane permeability

Answer 7

Temperatures below zero - particles do not have much energy so are packed tightly together membrane is rigid. Channel and carrier proteins deform increasing the permeability of the membrane. Ice crystals may form and pierce the membrane making it highly permeable when it thaws.
0-45 phospholipids can move membrane is partially permeable temp increases so does permeability
Above 45 - the bilayer starts to melt channel proteins deform membrane permeability increases