CH 27 (2): Ketone Bodies

These flashcards cover key concepts related to fatty acid metabolism, ketone bodies, and the implications of diet and metabolic states.

An isomerase is needed.

What is required for the oxidation of unsaturated fatty acids starting on an odd-numbered carbon?

It cannot be processed by acyl CoA dehydrogenase; isomerase converts it to trans-Δ2-enoyl CoA.

How are cis-Δ3-enoyl CoA processed in the degradation of monounsaturated fatty acids?

An isomerase and a reductase are required.

What enzymes are required to oxidize unsaturated fatty acids with double bonds starting on even-numbered carbons?

It converts 2,4-Dienoyl CoA into trans-Δ3-enoyl CoA.

What is the role of 2,4-dienoyl CoA reductase in fatty acid oxidation?

Propionyl CoA.

What fatty acid derivative is formed from odd-chain fatty acids during β-oxidation?

Propionyl CoA carboxylase.

Which enzyme adds a carbon to propionyl CoA to form methylmalonyl CoA?

Succinyl CoA.

What is formed from methylmalonyl CoA through the action of methylmalonyl CoA mutase?

Acetoacetate, β-hydroxybutyrate, and acetone.

Which ketone bodies are synthesized in the liver?

D-3-hydroxybutyrate dehydrogenase.

Which enzyme is responsible for the formation of D-3-hydroxybutyrate from acetoacetate?

Untreated diabetes.

What metabolic state can lead to excess ketone body production?

It leads to the formation of substantial amounts of ketone bodies due to high fat and low carbohydrate intake.

How does a ketogenic diet affect the production of ketone bodies?

Ketone bodies.

What is a major energy source for the brain during starvation?

Acidosis, referred to as diabetic ketosis.

What can result from excessive ketone body production in untreated diabetes?

Initially, protein degradation provides carbons for gluconeogenesis; after several days, ketone bodies reduce protein degradation.

How does starvation affect the utilization of protein in the body?

Accelerated protein degradation and potential death from loss of vital organ function.

What are the consequences of depleting triacylglycerols during starvation?

It drops, leading to acidemia.

What happens to blood pH during diabetic ketosis?

Excess consumption may promote obesity, atherosclerosis, and type 2 diabetes.

What distinguishes saturated and trans unsaturated fatty acids in relation to health?

It enters the cycle, but cannot lead to net synthesis of oxaloacetate or glucose.

What does acetyl CoA derived from fats contribute to the citric acid cycle?

Glucose cannot enter cells; energy must come from fats.

What condition exists when insulin is absent during fatty acid metabolism?

Propionyl CoA is generated.

What happens during the final step of β-oxidation for odd-chain fatty acids?

250 kcal in blood and 1700 kcal in the liver.

How much glucose is available in blood and liver for a typical 70-kg man?

They are lost as CO2.

What do the two carbon atoms from acetyl CoA release during the citric acid cycle?

Blood pH drops.

What change occurs in the blood pH due to overproduction of ketone bodies?

Accelerated protein degradation leading to tissue failure.

What is the outcome of patients who undergo prolonged fasting after depleting fat reserves?

Fats.

What represents the largest energy store in the body?