Biochemistry 2280A Study Guide - Midterm Guide: Ketone Bodies, Triglyceride, Cytosol
Biochemistry 2280 – Midterm
Acetyl-CoA & Fatty Acids
Identify the different metabolic fates of acetyl-CoA and how these pathways are related
- ketone bodies
- cholesterol
- fatty acids
- citric acid cycle
Explain in general terms how fatty acids are synthesized, degraded, and moved across the inner
mitochondrial membrane, including the reactants consumed and products created, but not
their stoichiometries
• whenever energy is needed from fat storage, triacylglycerol is
broken down into glycerol and three fatty acids
• these fatty acids enter the bloodstream and are used as fuel (liver,
muscle, NOT brain)
- also converted to acetyl-CoA
• the released glycerol can go into gluconeogenesis and the liver
beta-oxidation of fatty acids (breakdown)
• if a cell needs fatty acids for fuel, it’ll move it from the blood into
the cytosol
• fatty acid is activated with CoA in a reaction that is driven by ATP
• this makes acyl-CoA
• that is oxidized; each set of reactions makes an acetyl-CoA, FADH2,
NADH and a fatty acyl-CoA chain that is two carbons shorter than
before
• this repeats until it is completely oxidized to acetyl-CoA
• this sometimes works for unsaturated fatty acids, but these may require consumption
of NADPH and make fewer FADH2
• there is no ATP directly made in this process, but lots of energy
Biosynthesis of fatty acids
• when the body’s energy supply is high, acetyl-CoA is converted to fatty acids
• this occurs in the cytosol, but acetyl-CoA is produced in the matrix
• acetyl-CoA is moved from the matrix to the cytosol by the tricarboxylate transport
system
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