6. Fat Mobilisation and Utilisation

Question 1

what happens during fatty acid oxidation?

Answer 1

fatty acids are transported across the inner mitochondrial membrane. This transport is carnitine dependent.
Fatty acids are then broken down to acetyl-CoA in the mitochondria through beta oxidation.

Question 2

what is the difference between saturated and unsaturated fatty acids?

Answer 2

saturated = no double bonds
unsaturated = 1 or more double bonds

Question 3

which fatty acid can your liver not make? so must intake it through diet

Answer 3

alpha-Linolenic acid 18:3 (n-3)

Question 4

What is a trans fatty acid? and what fatty acid can be made to this when heated.

Answer 4

A trans fatty acid is a heated unsaturated fatty acid in which the cis bond of the acid is altered so that instead of both of the hydrogens facing the same way, one faces upwards and the other faces downwards.

Question 5

fatty acids are not soluble in water therefore are attached to a protein. what are these proteins in

1. Plasma
2. Cytoplasm
3. what other structure to the form?

Answer 5

1. protein = albumin
2. Protein = FABP
3. Form micelle like structures

Question 6

How are fats mobilised from their store through lipoprotein lipase?

Answer 6

Bulk of fat is carried in lipoproteins where the fatty acids are released and taken up by the cell by lipoprotein lipase (Allows the fatty acids to move across the membrane)

Question 7

How are fats mobilised through insulin and lipid storage/release

Answer 7

Triacylglycerol in the blood will be broken down into free fatty acids by lipoprotein lipase. The enzymes activity is activated more through insulin. they can then be take up into the surrounding tissues where it can then by stored as TAG.
Insulin also suppressed HSL (hormone sensitive lipase) which prevents the breakdown of TAG in the tissues into FFA and glycerol - which can be more harmful

Question 8

what is lipolysis?

Answer 8

breaking the fatty acids of the glycerol backbone

Question 9

What is beta-oxidation?

Answer 9

liberating acetyl-CoA off a chain to go into the TCA

Question 10

What factors activate lipolysis?

Answer 10

exercise 
AMP
Cortisol
Growth hormone
Adrenergic stimulation
Adrenaline
Glucagon
Leptin

Question 11

What is the main factor that inhibits lipolysis?

Answer 11

insulin

Question 12

What is the role of lipase?

Answer 12

breaks down TAG into glycerol and fatty acids.

Question 13

How are fatty acids taken up into the cell?

Answer 13

through a fatty acid binding protein (transport proteins - mainly FAT/CD36)

Question 14

How is fat taken up into the mitochondria?

Answer 14

Fatty acid needs to be attached to a CoA to form acyl-CoA. this is done through the enzyme Acyl-CoA synthase. ATP is required

The acyl part of the Acyl-CoA moves through the outer mitochondrial membrane through CTP1. It is transferred from acyl-CoA to carnitine to form acylcarnitine –> this is a limiting step.

Acylcarnitine moves through the intermitochondrial membrane through CPT II and transfers the acyl to a CoA to form fatty acyl-CoA. The carnitine then moves back to the intermembrane space

Question 15

what are the sources of fat for oxidation by working muscle?

Answer 15

Fatty acids from adipose tissue (HSL)
Fatty acids from tag in muscle (HSL)
Lipoproteins synthesised in the liver (VLDL, LDL) or in the intestine (chylomicrons) (LPL)