Flashcards in L22- Fatty acid metabolism Deck (17):
What are the major forms of stored energy in vertebrates?
Triacylglycerols and glycogen
How long can glycogen and TGs supply for?
Glycogen- supply energy for less than an hour
sustained work is fueled by metabolism of TGs
Where does the digestion of dietary lipids happen?
What produces bile and what does it do?
The liver. Bile emulsifies fats
What are lipids absorbed as?
In the intestine converted to fatty acylCoA and then triacylglycerols. (TGs)
How are fats transported in the blood stream?
In the form of cholymicrons :
TG and cholesterol and specific proteins
What does the beta oxidation pathway do and where?
Degrades fatty acids two carbons at a time. takes place in the mitochondria.
What are the 3 stages of beta oxidation pathway?
1. activation of fatty acids in the cytosol
2. transport into the mitochondria
3. degradation to two-carbon fragments (as acetyl coA)
in the mitochondria matrix
In the 2nd step-transport of fatty acel coA into mitochondia, how does it get in?
Using carrier molecule-carnitine.
fatty acid had been activated, joined to coA
Transferred to carnitine. makes acyl carnitine. Goes into mitochondria thourhg the translocase. Then carnitine drops off the fatty acid to CoA again.
Each round of beta oxidation makes what?
Fatty acyl CoA (2 carbons shorter each round)
What is the net yield of ATP per palmitate oxidizes to 16 CO2?
its a 16 carbon fatty acid chian. makes 106 atp
Where and when does fatty acid synthesis occur?
Mainly in the liver and adipocytes- in the cytosol.
When glucose is plentiful, excess CoA is made in glycolysis, use for fatty acid synthesis.
Where does NADPH come from for FA synthesis?
Glucose oxidation in the pentose phosphate pathway
What does acetyl CoA carboxylase do?
Catalyzes the formation of malonyl CoA from acetyl CoA. (adds one carbon)
Then 2 carbons from malonyl coA are added to the growing fatty acid chain.
2 carbons at a time
For fuel how are lipids transported?
liproproteins (eg LDLs)
What happens to FAs in fed state?
FAs stored in adipose tissue.
Insulin levels high- stimulates AcetylCoA carboxylase.
Increases FA synthesis.