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Lecture 22
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Hormonal regulation
The TCA
The brain problem…
Most energy stored as fatty acids
Brain only uses Glc
Fatty acids  Glc?
How does brain function during starvation?
Production of ketone bodies
Starvation  Glycogen = 1 day
Amino acids  Glc. BUT…
Muscles can use fatty acids (↓ need for Glc)
Gluconeogenesis ↓ OAA, so ↓ TCA
Without TCA, liver makes “Ketone bodies” from fats
Ketone bodies
Diabetes & ketone bodies
Starvation  ↑ KB  Used by brain
Extreme starvation  Muscle breakdown
No insulin  ↑ Blood sugar, AND ↑ FA breakdown
Too much Acetyl CoA  ↑ Ketone bodies
Brain has plenty of Glc!
↑ Ketone bodies in blood = ↓ pH  ↑ Death
If only…
Making fatty acids = adding 2 Cs to chain!
AcCoA  Malonyl CoA
ACP in FAS
FAS
FAS
Fatty acid synthesis
Substrate shuttling in FAS
Substrate shuttling in FAS
Further steps…
Further steps…
Regulation of FAS & breakdown
Allosteric regulation of ACC