Beta Oxidation: Energy Yield from Fatty Acid Oxidation Quiz and Flashcards

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Questions and Answers

What is the net energy yield from the oxidation of one molecule of palmitoyl CoA to CO2 and H2O?

131 ATP

125 ATP

129 ATP (correct)

133 ATP

What is the role of flavin adenine dinucleotide (FAD) in β-oxidation?

To donate electrons during the electron transport chain

To synthesize fatty acids from acetyl CoA

To accept electrons during the β-oxidation of fatty acids (correct)

To generate ATP during oxidative phosphorylation

What is the name of the enzyme that is deficient in medium-chain fatty acyl CoA dehydrogenase deficiency?

VLCFA CoA dehydrogenase

Short-chain fatty acyl CoA dehydrogenase

Medium-chain fatty acyl CoA dehydrogenase (correct)

Long-chain fatty acyl CoA dehydrogenase

During β-oxidation, how many molecules of acetyl CoA are produced from one molecule of palmitoyl CoA?

8 Signup and view all the answers

What is the energy cost of activating a fatty acid for β-oxidation?

2 ATP Signup and view all the answers

How many molecules of NADH are produced during the β-oxidation of one molecule of palmitoyl CoA?

7 Signup and view all the answers

What is the name of the coenzyme that is reduced during the β-oxidation of fatty acids?

FAD Signup and view all the answers

What is the product of the β-oxidation of palmitoyl CoA?

CO2 and H2O Signup and view all the answers

How many ATP molecules are generated when one acetyl-CoA is converted to CO2 and H2O by the TCA cycle?

12 Signup and view all the answers

What is the number of FADH2 molecules generated in the β-oxidation of one palmitoyl-CoA molecule?

7 Signup and view all the answers

What is the total ATP yield from the complete oxidation of one palmitoyl-CoA molecule?

129 Signup and view all the answers

How many NADH molecules are generated when one palmitoyl-CoA molecule is β-oxidized to acetyl-CoA?

14 Signup and view all the answers

What is the ATP yield when one FADH2 is oxidized by the electron transport chain?

3 Signup and view all the answers

How many carbon atoms are present in the intermediate C10-CoA?

10 Signup and view all the answers

What is the byproduct of the TCA cycle when acetyl-CoA is converted to CO2 and H2O?

H2O Signup and view all the answers

How many ATP molecules are generated when one NADH is oxidized by the electron transport chain?

3 Signup and view all the answers

What is the intermediate molecule formed when C2-CoA is converted to acetyl-CoA?

Acetyl-CoA Signup and view all the answers

How many ATP molecules are generated when one FADH2 is oxidized by the electron transport chain and the TCA cycle?

12 Signup and view all the answers

What is the primary function of the CPT system in mitochondria?

To oxidize long-chain fatty acids Signup and view all the answers

What is the result of the first cycle of β-oxidation?

Shortening of the fatty acid chain by two carbons Signup and view all the answers

Which of the following is a characteristic of medium-chain fatty acids?

They are plentiful in human milk Signup and view all the answers

What is the role of 3-hydroxyacyl CoA dehydrogenase in β-oxidation?

To reduce NAD+ to NADH Signup and view all the answers

Which of the following is NOT a step in the β-oxidation reaction?

Synthesis of ATP Signup and view all the answers

What is the purpose of the four reactions in the β-oxidation cycle?

To shorten the fatty acid chain by two carbons Signup and view all the answers

What is the effect of malonyl CoA on medium-chain fatty acid oxidation?

It has no effect on the oxidation of medium-chain fatty acids Signup and view all the answers

What is the role of matrix enzymes in β-oxidation?

To activate medium-chain fatty acids to their CoA derivatives Signup and view all the answers

Study Notes

Energy Yield from Fatty Acid Oxidation

The energy yield from the trans double bond between carbon 2 and carbon 3 in the β-oxidation pathway is high.
The oxidation of a molecule of palmitoyl CoA to CO2 and H2O produces 8 acetyl CoA, 7 NADH, and 7 FADH2, from which 131 ATP can be generated.
However, the activation of the fatty acid requires 2 ATP, so the net yield from palmitate is 129 ATP.

Medium-Chain Fatty Acyl CoA Dehydrogenase Deficiency

In mitochondria, there are four fatty acyl CoA dehydrogenase species, each with distinct but overlapping specificity for either short-, medium-, long-, or VLCFAs.
Medium-chain fatty acyl CoA dehydrogenase deficiency can be compensated by other dehydrogenases.

Mobilization of Stored Fats and Oxidation of Fatty Acids

The number of carbons contained in the intermediates of β-oxidation determines the energy yield.
Each acetyl CoA produced during β-oxidation yields 12 ATP when converted to CO2 and H2O by the TCA cycle.
FADH2 and NADH produced during β-oxidation yield 2 ATP and 3 ATP, respectively, when oxidized by the electron transport chain.

Entry of Short- and Medium-Chain Fatty Acids into the Mitochondria

Fatty acids shorter than 12 carbons can cross the inner mitochondrial membrane without the aid of carnitine or the CPT system.
Once inside the mitochondria, they are activated to their CoA derivatives by matrix enzymes and are oxidized.

Reactions of β-Oxidation

The first cycle of β-oxidation involves a sequence of four reactions involving the β-carbon (carbon 3) that results in shortening the fatty acid chain by two carbons at the carboxylate end.
The oxidation of medium-chain fatty acids is not dependent on CPT-I and is not subject to inhibition by malonyl CoA.

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Description

Calculation of energy yield from fatty acid oxidation, including the β-oxidation pathway and ATP generation. Also covers Medium-Chain Fatty Acyl CoA Dehydrogenase Deficiency.

Fatty Acid Oxidation and Energy Yield

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