lipids 2-sythesis of FA

Question 1

what is the name of the process which sythesises FA and where does it take place?

Answer 1

beta-oxidation. takes place in the mitochondrial matrix.

Question 2

how does beta-oxidation take place

Answer 2

1- activation- coenzyme A and ATP are used to activate FA into fatty acyl CoA in cytoplasm.
2- transport- fatty acyl CoA is transported into mitochondrial matrix via carnitine in form of acyl carnatine
3- degradation-
dehydrogenation: to produce FADH2 from FAD
hydration: using H20
dehydrogenation: produces NADH from NAD+
Thiolysis: produces Acetyl CoA

Question 3

products in terms of ATP when palmitate is beta-oxidised.

Answer 3

FADH2= 2ATP
NADH=3ATP
acetyl CoA =12 ATP
16 carbon Palmitate is broken down in 8 stages as the FA loses 2 Carbon atoms and forms 1 Acetyl CoA for every Beta-oxidation so
2x7+3x7+12x8= 131 ATP.
But 2 ATP lost in production of pamitoyl CoA so 129 ATP

Question 4

carnitine- where is it formed and what does its dysfunction lead to?

Answer 4

carnitine-produced in the kidneys and liver from AA such as lysine absorbed from meat.
deficiency prevents formation of CAT-1 or carnitine-palmitoyl transferase.
this prevents:
1-hypoglycemia
2-coma
3-prevention of FA for gluconeogenesis in the liver,
4- in muscle cells prevents exercise and FA consumption
5- beta-oxidation

Question 5

what is the rate determining step of beta-oxidation and what controls it?

Answer 5

It is the formation of acyl carnatine.
Fatty acyl- CoA + carnatine =Acyl carnatine.
malonyl- CoA inhibits the production of CAT-1 which controls the production of acyl carnatine.

Question 6

what happens during fasting

Answer 6

fatty acids broken down so excess Acetyl-CoA produced.

Activates pyruvate carboxylase so more ketone bodies to be produced as pyruvate to glucose reaction is irreversible.

Question 7

properties of ketone bodies

-where are they used?

Answer 7

water soluble so do not need to be transported round in lipoproteins.
produced in liver but not used by liver cells
used by the brain cell and the cardiac/skeletal muscle

Question 8

what happens when there is xs fasting or diabetes

Answer 8

1- too many ketone bodies produces ( ketonemia ,ketouria )
2-lowers the Ph of the blood which can cause coma

3-happens in diabetes as Acetyl CoA cannot be processed after beta oxidation