Module 2: Cell Membranes

Question 1

State 3 key features of plasma membranes

Answer 1

Partially permeable barriers to control which substances enter or leave the cell
Site of chemical reactions
Contain receptors where hormones and drugs can bind

Question 2

Describe 3 roles of membranes within cells

Answer 2

Control which substances enter or leave organelles
Site of chemical reactions
Compartmentalisation

Question 3

Describe the function of phospholipids

Answer 3

Form the bilayer of plasma membranes
Act as barrier to water soluble substances

Question 4

Describe the function of cholesterol

Answer 4

Adds stability to the membrane (less fluid, more rigid)

Question 5

Describe the function of glycolipids

Answer 5

Stabilise the plasma membrane by forming H bonds with water
Act as receptors for hormones and drugs, passing on signals to intracellular components
Act as antigens. Cell recognition of self and non-self cells.

Question 6

Describe the function of proteins on plasma membranes

Answer 6

Channel proteins are used for facilitated diffusion
Carrier proteins are used for active transport
Act as antigens. Cell recognition of self and non-self cells.

Question 7

Describe the function of glycoproteins (a molecule that consists of a carbohydrate and a protein molecule)

Answer 7

Stabilise the membrane by forming H bonds with water
Act as receptors for hormones and drugs, passing on signals to intracellular components
Act as antigens. Cell recognition of self and non-self cells

Question 8

Describe the Fluid Mosaic Model of plasma membrane structure

Answer 8

Phospholipids form a bilayer
Hydrophobic tails on the inside
Hydrophilic heads on the outside
Proteins scattered through the bilayer

Question 9

Explain the term cell signalling

Answer 9

Cell to cell communication
One cell leases a messenger molecule
Detected by a receptor on another cell that has a complementary shape to the messenger molecule
Appropriate response is made

Question 10

Describe and explain the effect of changing temperature on plasma membrane structure and permeability