Breakdown of fatty acids and synthesis of ketone bodies Flashcards
What can triaclyglyerols form
-Fatty acids
What can fatty acids form
- triacylglycerols
- membrane lipids
- Acetyl CoA
What can Acetyl CoA form
- fatty acids
- cholesterol
- ketone bodies
- can go into citric acid cycle
When does acetyl CoA form ketone bodies and why
When there’s a build up of Acetyl CoA because of a shortage of oxaloacetate
How are free fatty acids and glycerol formed in adipose tissue
- Glucagon or adrenaline bind to receptor
- hormone sensitive lipase activated
- This hydrolyses triacylglycerol to free fatty acids and glycerol
How are free fatty acids transported to skeletal muscle from adipose
Bind to ALBUMIN and gets transported
What happens to the FFA-albumin complex when it has reached skeletal muscle
FFA converted to acetyl CoA in beta-oxidation
What happens to the acetyl CoA formed in skeletal muscl
Goes into TCA cycle to form Co2 H2o and ATP
Why can’t FFA be used in the brain
Because albumin can’t cross the blood-brain barrier
What happens in beta-oxidation of fatty acids to form Acetyl CoA
- Activation of long chain fatty acids in cytosol to form fatty acyl CoA
- Import of activated LCFAs into mitochondria
- beta oxidation in mitochondrial matrix to generate NADH, FADH2. and acetyl CoA
What is the carnitine shuttle used for
to cross CoA esters across the mitochondrial inner membrane
What cannot cross the mitochondrial inner membrane
CoA esters
What happens in the cytosol of the carnitine shuttle (first stage)
-acetyl CoA and free fatty acids present in cytosol, and acetyl CoA is replaced with carnitine by carnitine acetyltransferase and this moves through channel
What happens in the second stage of the carnitine shuttle
-Carnitine acetyltransferase 2 removes carnitine and replaces it with acyl CoA to add back onto the FFA
What happens in the third stage of the carnitine shuttle
Carnitine travels back through membrane into cytosol to bind to more FFA’s
Why does carnitine shuttle take place
This all occurs because CoA cannot cross the mitochondrial inner membrane
Where is carnitine synthesised
In liver and kidney and supplied to muscles by kidney via blood
What are fatty acyl groups subjected to
- OXidation
- Hydration
- Oxidation
- Thiolytic cleavage generate acetylCoA
What does oxidation of fatty acids generate
double bond on C2 (trans) and FADH2
what does hydration of fatty acids generate
Generates OH on C3
What does further oxidation of fatty acids generate
Carbonyl on C3 and NADH
What does thiolytic cleavage generate
AcetylCoA and shortened fatty acylCOA
Why are ketonic bodies important
Fuel source for brain during starvation
What are ketonic bodies made from
AcetylCoA in liver mitochondria
When does ketone body synthesis occur
When levels of AcCoA are high (starvation)
Why can babies become ketotic quicklt
Because of small glycogen stores
What are the two ketone bodies formed
- acetoacetate
- beta-hydroxybutyrate
What is acetoacetate reduced to and when
beta-hydroxybutyrate when NADH is high
What is in the liver when the body is in starvation mode
High NADH in liver when beta oxidation active
Can the liver utilize ketone bodies
No
What are ketone bodies used in
- Brain during starvation
- Heart muscle and kidney cortex in all conditions
