Chapter 16- Fatty Acids and Eicosanoids Flashcards
(55 cards)
What is a positive modulator of lipolysis?
glucagon or epinephrine
What does CPTI do?
transport acyl-CoA into mitochondria
What is lipolysis?
hydrolysis of TAGs in adipocytes -> forms free FA
what is a negative modulator of CPTI?
malonyl-CoA
In ketogenesis Fatty acyl-CoA can be converted to
2 Acetyl-CoA or Acetoacetyl-CoA (beta-oxidation)
Acetoacetyl-CoA is synthesized from what?
2 acetyl-CoA catalyzed by thiolase in starvation
In fed state what is the fate of acetyl-CoA?
TCA cycle -> glucose via gluconeogenesis
In ketogenesis what is acetoacetyl-CoA converted to and by what enzyme?
HMG-CoA via HMG-CoA synthase
In ketogenesis what is HMG-CoA converted to and by what enzyme?
Acetoacetate via HMG-CoA lyase
In ketogenesis what is Acetoacetate converted to and by what?
spontaneously decarboxylated to acetone
converted to 3-hydroxybutyrate via 3-hydroxybutyrate dehydrogenase
Are ketones used by the liver?
No, the liver lacks succinyl-CoA-acetoacetate-CoA transferase so it cannot use ketone bodies
How does the body use ketone bodies?
when ketone bodies released from liver -> transported to muscle (major), kidney (major), brain (only in starvation) -> oxidized for energy
What is the rate limiting step in ketogenesis?
HMG-CoA reductase, release of FA from adipose and uptake of acyl-CoA into mitochondria (CPTI)
where does cholesterol synthesis occur?
liver cytosol
Where does ketogenesis occur
liver mitochondria
How is acetone excreted?
by lungs, expiration
How are ketone bodies excreted?
urine
Why does ketogenesis occur?
During gluconeogenesis acetyl-CoA uses oxaloacetate in the formation of citrate and eventually glucose. When oxaloacetate is depleted ketogenesis proceeds so acetyl-CoA can be utilized for energy.
Where is the major site of FA synthesis?
liver cytosol
Synthesis of long chain saturated FA is from?
Synthesized from dietary glucose via pyruvate
Where are enzymes for FA synthesis located?
The Es are localized in the cytosol, completely different from the mitochondrial Es for FA degradation
To synthesize palmitic acid, polymerization of initial 2 carbon units are from what
Acetyl-CoA, carbons 15, 16
What molecules are required for FA synthesis?
reduced NADPH, ATP, biotin, CO2, H2O
What is the initial and controlling step of FA synthesis?
production of Malonyl-CoA, carboxylation reaction and requires biotin
