Lipid Membranes

Question 0

Function of the lipid membrane

Answer 0

Continuous, highly selective permeability barrier
Control of the enclosed chemical environement
Recognition of signalling molecules, adhesion proteins and for immune surveillance
Signal generation in response to stimuli (chemical or electrical)

Question 1

Membrane composition of lipid, protein and carbohydrate in percentage.

Answer 1

40% lipid
60% protein
1-10% carbohydrate

Question 2

Give examples of where different regions of the membrane have different functions.

Answer 2

Interact with the basement membrane or adjacent cells
Specialised for secretion/absorption/transport
Synapses
Conduction of electrical signals

Question 3

What does amphipathic mean?

Answer 3

Has both hydrophobic and hydrophilic regions

Question 4

What types of molecule can be found in the head of a phospholipid?
Which is rarest and why is it essential?

Answer 4

Choline, amine, amino acid, sugar

Sugars are the rarest, important for the synthesis of signal molecules.

Question 5

What form of double bond introduces a kink in a fatty acid

Answer 5

Cis

Question 6

What is the function of sphingomyelin

Answer 6

Acts as a base for glycolipids

Myelin sheath

Question 7

Describe two types of glycolipid

Answer 7

Cerebroside - one simple sugar

Ganglioside - complex oligosaccharide

Question 8

What is a liposome?

Answer 8

A phospholipid bilayer which fully encloses a water-filled space.

Question 9

Describe the motion of phospholipids.

Answer 9

Flexion/rotation
Lateral diffusion
Flip flop (rare)

Question 10

What is required in the diet so we can have fatty acids with kinks?

Answer 10

Polyunsaturated fats

Question 11

Describe the structure of cholesterol

Answer 11

Rigid planar steroid ring with -OH group

Non polar hydrocarbon tail

Question 12

Function of cholesterol

Answer 12

Allows the membrane to remain fluid with minimal energy (i.e. Low temperatures) and maintains rigidity at high temperatures.

Question 13

Describe the relationship between net rate of transport and concentration difference in passive transport.

Answer 13

Net rate of transport is proportional to the concentration difference (linear relationship)

Question 14

Describe the role of transport

Answer 14

Maintain ionic composition
Maintain intracellular pH
Regulate volume
Concentrate metabolites for fuel
Excrete waste and toxic compounds
Generate ion gradients for nerve/muscle cells