Exam 3 (Cole) Flashcards
Names of the 3 ketone bodies produced in ketogenesis
Acetoacetate, acetone, B-hydroxybutyrate
Where does ketogenesis take place?
Mitochondria in the liver
What’s the starting substrate of ketogenesis?
Acetyl-CoA
Why do we make ketone bodies?
The brain can break them down since they are water-soluble form of lipid derived energy when glucose levels are low
Why are ketone bodies formed in uncontrolled type I diabetes?
Oxaloacetate gets used up for gluconeogenesis so acetyl-CoA can no longer be used in the citric acid cycle. Instead it goes to the mitochondria in the liver to create ketone bodies
What is the role of carnitine acyltransferases?
Transports fatty acids into the mitochondrial matrix
Why are ketone bodies formed in uncontrollable type I diabetes?
Too much glucose in the blood + low insulin causes fatty acids to be dumped into the liver. This causes low-yieldbeta oxidation where acetyl-CoA can no longer be used in the citric acid cycle (too little oxaloacetate) so undergoes ketogenesis. Too many ketone bodies are produced which can cause ketoacidosis
What are eicosinoids synthesized from?
Arachadonic acid
Which drug inhibits COX1 and COX2 (cyclooxygenase)?
NSAID’s (ibuprofen + asprin)
What’s the order of formation for eicosinoids?
Arachidonic acid –> cox1 / cox2 –> prostoglandins / thromboxanes
What do COX’s form before they become prostaglandin/thromboxane?
They form ring structures: 5-membered for prostaglandin, 6-membered thromboxane
What catalyzes the first step in the synthesis of leukotrienes?
Lipoxygenase
What is the role of malonyl-CoA
Inhibits carnitine acyltransferase I
Why is the entry of fatty acids into the mitochondria regulated?
If there’s an increase in malonyl CoA, that means that we’re synthesizing fatty acids. If we’re synthesizing, we do not need to break them down for energy so beta-oxidation is shut off
What is the product of acetyl-carboxylase in fatty acid synthesis?
Malolnyl-CoA
How do acetyl-CoA and NADPH get to the cytoplasm?
Citrate shuttle
What is the regulated enzyme in fatty acid synthesis?
Acetyl-CoA carboxylase
What does acetyl-CoA carboxylase require in fatty acid synthesis?
Biotin, because it’s a carboxylation reaction which requires 3 things and 1 of them is ATP
Does acetyl-CoA carboxylase require ATP?
Yes
What is the purpose of fatty acid synthesis?
During a fed state, we store energy by converting acetyl Co-A into fatty acids which can be stored as triglycerides in adipose tissue
What is the purpose of hormone-sensitive lipase?
During a fasting state, we break down triglyerides into free fatty acids and glycerol to use as fuel
What inhibits hormone sensitive lipase?
Insulin
What is the purpose of making malonyl-CoA?
To drive fatty acid synthesis via energy release during condensation and loss of CO2
How does citrate relate to fatty acid synthesis?
Citrate is a sign of being well-fed (TCA cycle very active), so it activates acetyl-CoA carboxylase
