Fatty Acid Catabolism

Question 1

Which organs are involved in lipid digestion?

Answer 1

Stomach and small intestine.

Question 2

What is the main function of triacylglycerol metabolism?

Answer 2

Synthesis and degradation of triacylglycerols.

Question 3

How much ATP is produced from β-oxidation of one palmitoyl CoA (16 carbons)?

Answer 3

129 ATP

Question 4

How much ATP is produced from glycolysis of one glucose (6 carbons)?

Answer 4

38 ATP

Question 5

What is the precursor for de novo synthesis of fatty acids and cholesterol?

Answer 5

Acetyl-CoA

Question 6

What compound extends fatty acids during synthesis?

Answer 6

Malonyl-CoA

Question 7

What is the structural basis for steroid-based hormones and biomolecules?

Answer 7

Cholesterol

Question 8

What are the main products of β-oxidation?

Answer 8

Acetyl-CoA, NADH, and QH2

Question 9

Where does β-oxidation occur in eukaryotic cells?

Answer 9

In the mitochondria and peroxisomes.

Question 10

What type of reaction initiates β-oxidation?

Answer 10

Oxidation of the acyl group.

Question 11

What is the first step of β-oxidation?

Answer 11

Installation of a trans-C2/C3 unsaturation using FAD, producing FADH2.

Question 12

What is the second step of β-oxidation?

Answer 12

β-Hydration of the alkene (trans-2-enoyl CoA).

Question 13

What happens in the third step of β-oxidation?

Answer 13

Oxidation of the 2° alcohol to a β-keto group using NAD+, forming NADH.

Question 14

What is the fourth step of β-oxidation?

Answer 14

Thiolysis and the release of acetyl-CoA.

Question 15

Which cofactor is required for the first oxidation step?

Answer 15

FAD (Flavin adenine dinucleotide).

Question 16

What type of reaction is the thiolysis step similar to?

Answer 16

Retro-Claisen condensation.

Question 17

What is produced after one cycle of β-oxidation?

Answer 17

Acetyl-CoA and an (n-2)-acyl-CoA.

Question 18

What is the nucleophile in the thiolysis step?

Answer 18

HS-CoA (Coenzyme A).

Question 19

How many steps are involved in each cycle of β-oxidation?

Answer 19

Four steps.

Question 20

What happens to the shortened acyl-CoA after one cycle?

Answer 20

It re-enters the β-oxidation cycle.

Question 21

Why is β-oxidation crucial for energy production?

Answer 21

It provides acetyl-CoA for the citric acid cycle and NADH/QH2 for the electron transport chain.

Question 22

What happens if there is a defect in β-oxidation?

Answer 22

It can lead to energy deficiencies and accumulation of fatty acids.

Question 23

Why is FAD used in the first oxidation instead of NAD+?

Answer 23

FAD is better suited for oxidizing saturated carbon-carbon bonds.

Question 24

Which tissues rely heavily on β-oxidation for energy?

Answer 24

Heart and skeletal muscle.

Question 25

How is β-oxidation regulated?

Answer 25

By the availability of fatty acids, malonyl-CoA levels, and energy demands.

Question 26

What is the importance of peroxisomal β-oxidation?

Answer 26

It handles very-long-chain fatty acids that mitochondria cannot process.

Question 27

How many ATP does 1 FADH2 produce in fatty acid catabolism?

Answer 27

2 ATP

Question 28

How many ATP does 1 NADH produce in fatty acid catabolism?

Answer 28

3 ATP

Question 29

How many ATP does 1 acetyl CoA produce in fatty acid catabolism?

Answer 29

12 ATP

Question 30

Where and how are fatty acids first activated? What is the ATP usage here?

Answer 30

In the cytoplasm by binding to CoA using the enzyme acyl-CoA synthetase, forming acyl-CoA; consumes 2 ATP equivalents.

Question 31

Describe the transportation of long chain fatty acyl into the mitochondria.

Answer 31

Long-chain fatty acyl-CoA is transported across the mitochondrial membrane using the carnitine shuttle.

Question 32

What are the enzymes involved in the carnitine shuttle?

Answer 32

Carnitine palmitoyltransferase I (CPT-I) (outer membrane) and CPT-II (inner membrane)

Question 33

What do peroxisomes generate for energy? Where are those products exported after?

Answer 33

Acetyl-CoA and hydrogen peroxide instead of FADH2 for energy; acetyl CoA is exported to the mitochondria for further oxidation

Question 34

What do mitochondria produce? Where are those products exported after?

Answer 34

Produces acetyl-CoA, NADH, and FADH₂, which enter the citric acid cycle and electron transport chain for ATP generation.

Question 35

Mitochondria is the primary site for ______________.

Answer 35

B-oxidation