Lipid metabolism Flashcards
What are fatty acids useful for?
They are precursor building blocks
What are triglycerides useful for?
Energy storage.
What are phospholipids useful for?
They form the main primary component of cell membranes.
What 3 things can cholesterol be used for?
1) fat transport
2) rigidity in the cell membrane
3) precursor to bile salts and steroid hormones
Are most naturally occurring fats found in the trans or cis configuration?
Cis.
During fatty acid activation, what do FA, ATP and CoA form?
Acyl-CoA, AMP and PPi
Where does FA activation occur?
The cytosol.
In order for Acyl-CoA FA to be transported into the mitochondria, what must it be bound to, and what is the bond used?
It is bound to carnitine, via an ester-linkage, to from acyl-carnitine.
How does acyl-carnitine enter the mitochondria?
It uses a transport protein.
During beta oxidation, what is formed when FAD dehydrogenates the fatty acid?
FADH2 and a carbon double bond in the FA
What happens to the carbon double bond?
It is hydrated to form an OH- group
How does NAD further dehydrogenate the FA?
It removes H+ to form NADH and a C=O bond/
After entering the mitochondria, what is removed and added to the FA?
The carnitine is removed and the CoA-SH is replaced.
Which carbon is the alpha carbon?
The carbon next to the carboxyl group
Which carbon is the beta carbon?
The second carbon from the carboxyl group
Where is the carbon-carbon double bond found?
Between the alpha and beta carbon
On which carbon does the C=O form?
The beta carbon
What does thiolase do to the FA after the C=O is formed?
It cleaves the bond between the alpha and beta carbon, removing CoA-SH. The CoA-SH is then replaced onto the beta carbon to reform the chain. This also releases
How many FADH2/NADH are produced per cycle of bet-oxidation?
1 of each
What is released in beta oxidation?
Acyl CoA and a fatty acid CoA
Where does the Acyl CoA go to become further metabolised?
TCA
What happens if the carbon chain in the fatty acid is >22C long?
The beta-oxidation must occur outside the mitochondria in a process called peroxysmal beta oxidation
How does insulin regulate the breakdown of lipids?
Insulin inhibits the release of free fatty acids from adipocytes.
How do glucagon and nor/adrenaline regulate lipid breakdown?
They stimulate adipocytes to release free fatty acids.
What is malonyl CoA?
A metabolite of lipids.
how does Malonyl-CoA regulate lipid breakdown?
It inhibits transport of FA-carnitine-CoA-SH into mitochondria
