lipids 2 Flashcards
(24 cards)
Name the process where fatty acids are broken down in the tissue to release energy
Beta oxidation
What 3 products are produced from beta oxidation?
Acetyl CoA, FADH2, NADH
can fatty acids be converted to glucose?
NO
how many carbons are degraded at a time on fatty acids in the beta-oxidation pathway?
2
where does beta-oxidation occur?
mitochondrial matrix
what are the three stages a fatty acid undergoes to enable beta oxidation?
- activation of fatty acids in the cytosol
- transport into the mitochondria
- degradation to two carbon fragments in mitochondrial matrix
in the cytosol, what is fatty acid activated to form?
fatty acyl CoA
how does fatty acyl CoA cross the outer mitochondrial membrane?
carnitine shuffle
what inhibits carnitine fatty acyl-transferase (CAT-1) or carnitine palmitoyl-transferase to prevent synthesis and degradation occurring simultaneously?
malonyl CoA
what are the risks with a carnitine palmitoyl-transferase deficiency (CAT-1)?
no beta oxidation so hypoglycaemia
coma on overnight fast
what are the 4 main steps of actual beta-oxidation?
- dehydrogenation (to produce FADH2)
- hydration
- dehydrogenation (to produce NADH)
- Thiolysis (cleaved) to produce acetyl CoA
What happens in step one dehydrogenation of beta oxidation?
Fatty acyl CoA is oxidised and a double bond is formed
FAD is reduced to FADH2
What happens in step 2?
water is added in to the double bond
What happens in step 3?
2 carbons are removed
NAD is reduced to NADH
What does thiolysis produce and what does this product feed into?
acetyl CoA into the citric acid cycle
what is the total energy yield from beta oxidation?
129ATP
where do very long chain fatty acids (greater than 22 carbons) undergo a preliminary beta oxidation?
peroxisomes
How many times does beta oxidation occur for one fatty acid molecule?
7 times as 16 carbons
can we convert fatty acid to glucose? why?
no
thermodynamically irreversible pyruvate to acetyl CoA step
What happens to excess Acetyl CoA?
made into ketone bodies
which parts of the body can use ketone bodies as an energy source?
cardia muscle
skeletal muscle
brain cells
where are ketone bodies formed?
*it cannot use them however
liver (mitochondrial matrix)
what is a sign of excess ketone bodies?
fruit odour in breath due to acetone
what leads to very high ketone body concentrations in the blood?
uncontrolled diabetes or starvation
