Fatty Acid Oxidation

Question 1

How are adipocyte TAGs mobilised in metabolic demands?

Answer 1

Action of hormone sensitive lipase.

Question 2

In metabolic demand, what results from the action of hormone sensitive lipase?

Answer 2

Forming of free fatty acids, releasing into bloodstream, binding soluble albumin.

Question 3

Lipases

Answer 3

Catalyse hydrolysis of Lipids into constiutent parts.

Question 4

What happens to the Adipocyte TAG released FFA after release into bloodstream?

Answer 4

Undergo catabolism by oxidation that releases free energy.

Question 5

Beta Oxidation

Answer 5

A series of enzyme catalyzed reactions operating in a repetitive fashion, degrading fatty acids by removal of two carbon units.

Question 6

What must happen to fatty acids before oxidation?

Answer 6

FA must be primed for reaction in an ATP-dependent acylation reaction, forming fatty acyl-CoA

Question 7

Acyl-CoA synthetase

Answer 7

Catalyses forming of fatty acyl-coa from fatty acids, before oxidtaion.

Question 8

Where are Acyl-CoA synthetases found?

Answer 8

The ER or OMM.

Question 9

Carnitine

Answer 9

This is used to transport fatty acids across the IMM

Question 10

Why is caritine required?

Answer 10

The long chained Fatty Acyl-CoA resulting from activation cannot freely traverse the INM.

Question 11

What mediates transfer of acyl groups across the mitochondrial membranes?

Answer 11

Carnitine Palmitoyl Transferases 1 and 2 on the internal/external surfaces of the IMM

Question 12

When the acyl portion of Acyl-CoA transfers to carnitine, how is it then transported into the mitochondria?

Answer 12

The carrier protein, carnitine carrier protein transports acyl-carnitine into the mitochondria, transferring free carnitine in the opposite direction.

Question 13

Pathway of Acyl-CoA transfer into the mitochondria?

Answer 13

Acyl groups of cytosolic Acyl-CoA transfer to carnitine, releasing CoA into cytosolic pool, acyl-carnitine transports into MM by carrier protein, where acyl transfer to mitochondrial Acyl, in tandem with carnitine returning to the cytosol.

Question 14

What are the general steps of beta oxidation?

Answer 14

Forming of trans C2-C3 double bond through Acyl-CoA dehydrogenase forming enoyl CoA
Hydration of double bond by enoyl-CoA hydratase forming 3-1, hydroxyacyl-CoA
NAD+ dependent dehydrogenation of 3-1 H-CoA by 3-1 H-CoAD forming beta-ketoacyl-CoA
C2-C3 cleavage catalysed by beta-ketoacyl-CoA thiolase forming acetyl-CoA and a new Acyl-CoA containng two few carbons than original.

Question 15

How does eta oxidation relate to the ETC?

Answer 15

ACDH involves removal of proton at Carbon A and transfer of hydride ion from Carbon B to FAD, forming FADH2, which reoxidises in ETC, supplying it with electrons.

Question 16

Acyl-CoA structure

Answer 16

A skeletal diagram with 6 points, C1 being replaced by a sulfur, with a CoA bound to it, C6 being an R group and C2 having a carbonyl.

Question 17

What is a potential cause of SIDS?

Answer 17

Medium chain acyl-CoA dehydrogenase deficiency, as glucose level decrease increases rate of fatty acid oxidation, thus SIDS can be caused by imbalance between glucose and fatty acid oxidation.

Question 18

Function of FA oxidation?

Answer 18

Generation of metabolic energy in the form of production of one NADH and one FADH2, with an acetyl CoA each cycle.

Question 19

What happens to beta oxidation derived Acetyl CoA?

Answer 19

Via the CAC it generates an additional FADH2 and 3 NADH, each reoxidised through OP to form ATP

Question 20

What is an example of the highly exergonic nature of FA oxidation?

Answer 20

Palmitoyl-CoA has C16 fatty acyl group able to go seven cycles of beta oxidation, yielding 7DAH2, 7 NADH and 8 acetyl CoA, where A-CoA yields 24 NADH, 8 GTP and 8 FADH, yielding 77.5 ATP in OP, whilst the 15 FADH2 yields 22.5 ATP.