Lipid Metabolism Flashcards

Flashcards covering key concepts in fatty acid oxidation, ketogenesis, fatty acid synthesis, and cholesterol metabolism.

What process provides energy to cells when glucose levels are low?

Fatty acid degradation

What enzyme differs in specificity by the size of the fatty acids?

Fatty acyl-CoA synthetases

What imports fatty acyl-CoA into the mitochondrial matrix?

Carnitine transport cycle

What inhibits mitochondrial import of fatty acyl-CoA when cell energy charge is high?

Malonyl-CoA

Where does fatty acid β-oxidation occur?

Mitochondria

What are the products of fatty acid β-oxidation?

FADH2, NADH, and acetyl-CoA

List the four enzymes involved in fatty acid β-oxidation.

Acyl-CoA dehydrogenase, enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, β-ketoacyl-CoA thiolase

What are the ketone bodies produced during ketogenesis?

Acetoacetate and D-β-hydroxybutyrate

From what organ are ketone bodies exported into muscle tissues?

Liver

How is acetyl CoA exported from the mitochondria to the cytosol when levels are too high?

Citrate shuttle

What enzyme is responsible for fatty acid synthesis?

Multifunctional enzyme using acyl carrier protein

What enzyme catalyzes the rate-limiting step in fatty acid synthesis?

Acetyl-CoA carboxylase

What are the four steps in the fatty acid synthesis reaction?

β-ketoacyl-ACP synthase, β-ketoacyl-ACP reductase, β-ketoacyl-ACP dehydratase, enoyl-ACP reductase

What is the final product of fatty acid synthesis?

Palmitate

What is the function of elongation enzymes in fatty acid synthesis?

Increase carbon chain in palmitate

What do desaturating enzymes produce?

Produce unsaturated fatty acids

From what is triacylglycerol formed?

From phosphatidic acid

Where does cholesterol synthesis primarily occur?

All cells, primarily in the liver

List the four stages of cholesterol synthesis.

Formation of mevalonate, formation of isopentenyl diphosphate, formation of squalene, cyclization of squalene

What enzyme catalyzes the rate-limiting step in cholesterol synthesis?

HMG-CoA reductase

What are the three major fates of cholesterol from the liver?

Stored in lipid droplets, packaged into lipoproteins, secreted into small intestines

What is the composition of lipoproteins?

Phospholipid monolayer containing cholesterol and apolipoproteins

What is the function of HDL particles in reverse cholesterol transport?

Remove cholesterol from peripheral tissues

Which protein controls cholesterol biosynthesis?

SREBP

How do statin drugs lower cholesterol levels?

Inhibit HMG-CoA reductase

What are the products of myristic acid (C14) being completely metabolized via β-oxidation?

6 NADH, 6 FADH2, 7 acetyl-CoA

How many rounds of fatty acid degradation are required to fully metabolize arachidonic acid (C20)?

9

What are the products of ketogenesis?

acetoacetate and D-β-hydroxybutyrate

By what mechanism are acetyl CoA levels exported when they are too high?

citrate shuttle

Which stage of cholesterol biosynthesis do statin drugs inhibit?

Stage 1