MCBG topic 7. lipids

Question 1

Are lipids more reduced or more oxidised than carbohydrates?

Answer 1

more reduced than carbohydrates meaning they have a higher energy content.
- release more energy when oxidised .

Question 2

describe how the carnitine shuttle works

Answer 2

• acyl group transferred to carnitine (outer mitochondrial membrane)
• acyl carnitine shuttled
• converted back into acetyl co A
• carnitine returned to cytosol

Question 3

how is the proton motivated force produced

Answer 3

electrons transferred from NADH and FAD2H to oxygen through a series of multi-component complexes with the release of free energy.
> used to move H+ inside to the outside of inner mitochondria membrane

Question 4

what is the role of the proton motivated force

Answer 4

forces protons back into the mitochondrial matrix through an ATP synthase complex driving the synthesis of ATP from ADP and Pi.

Question 5

what occurs during thermogenesis in brown adipose tissue mitochondria

Answer 5

• thermogenin protein allows the controlled re-entry of H+ into the matrix without driving ATP synthesis. (uncouples ATP synthesis from e- transport)> heat production

Question 6

how does thermogenesis occur in response to cold

Answer 6

• noradrenaline released stimulates lipolysis. B oxidation of fatty acids. NADH and FAD2H formed. drive ET and inc p.m.f.
• activated thermogenin. uncouples ATP synthesis from e- transport.

Question 7

how do uncoupling agents lead to an absence of fat and death?

Answer 7

• uncontrolled respiration occurs
• consumes large amount of fuels e.g. fa from adipose tissue
• consumes large amount of oxygen > hypoxia prevented by inc pulmonary activity
• less ATP made than normal under oxidative phosphorylation > energy lost as heat. high body temp.
• leads to death as high body temp tries to be combatted by increased sweating but leads to coma and death

Question 8

what two factors are required for the synthesis of ketone bodies?

when does this usually occur

Answer 8

• high availability of fatty acids for oxidation in the liver
• low plasma insulin : glucagon ratio

starvation
OR type 1 diabetes producing ketoacidosis.

Question 9

where and how are ketone bodies synthesised?

Answer 9

• in the liver
• from acetyl CoA
• produces hydroxymethyl glutaryl CoA (HGM coA)
  > converted to acetoacetate by lysase enzyme

activity of lysase enzyme controlled by insulin:glucagon ratio.
low= activated.