Deck 22: Fatty Acid Metabolism

Question 1

The coenzyme that supplies the reductive power for fatty acid synthesis is ______________.

Answer 1

NADPH

Question 2

In eukaryotes, the degradation of fatty acids occurs in the ___________________ (be specific).

Answer 2

mitochondrial matrix

Question 3

What is the approximate energy yield from complete oxidation of fatty acids?

A) 3 kcal g^-1
B) 4 kcal g^-1
C) 6 kcal g^-1
D) 9 kcal g^-1
E) 11 kcal g^-1

Answer 3

D

Question 4

The synthesis of fatty acids takes place in the _____________ of the cell.

Question 5

Glucagon and _______________ stimulate the breakdown of triacylglycerols by activation of a hormone-sensitive lipase.

Question 6

What molecule is required for the movement of long-chain fatty acyl groups from the cytosol into the mitochondrial matrix?

A) creatine
B) carnitine
C) creatinine
D) cholesterol
E) None of the answers is correct.

Question 7

What pathway degrades an acyl-CoA into acetyl CoA?

A) acyl transferase cycle
B) chylomicron cycle
C) glyoxylate cycle
D) carnitine cycle
E) $\beta$ oxidation

Question 8

Acetyl-CoA carboxylase is inactivated when the energy charge of the cell is___________ (high, low).

Question 9

The committed step of fatty acid synthesis is the formation of ________________.

Question 10

What tissue is the primary storage site for triacylglycerols in animals?

A) liver
B) adipose
C) kidney
D) heart
E) muscle

Question 11

The first step of $\beta$ oxidation is a(n) _________-linked oxidation of the fatty acyl chain.

Question 12

Prostaglandins and thromboxanes are synthesized from __________________, a 20-carbon fatty acid.

Question 13

What cholesterol derivatives facilitate the digestion of fats by incorporating dietary triacylglycerols into micelles in the intestine?

A) vitamin D
B) testosterone
C) bile acids
D) aldosterone
E) None of the answers is correct.

Question 14

Which of the following is an example of a short-lived, local-acting hormone?

A) prostaglandin
B) testosterone
C) estradiol
D) insulin
E) glucagon

Question 15

The levels of which metabolite determine whether acetyl-CoA, made from fatty acids, can enter the citric acid cycle?

A) citrate
B) succinyl CoA
C) oxaloacetate
D) $\alpha$ -ketoglutarate
E) None of the answers is correct.

Question 16

$\beta$ oxidation of odd-numbered fatty acids produces acetyl-CoA and _______________.

Question 17

What molecule is used to transport acetyl groups from the matrix to the cytoplasm?

A) acetyl-carnitine
B) succinyl CoA
C) oxaloacetate
D) $\alpha$ -ketoglutarate
E) citrate

Question 18

Acetoacetate and ________________ are referred to as ketone bodies and are major fuel sources for heart muscle.

Question 19

The enzyme methylmalonyl CoA mutase contains a derivative of _____ as its coenzyme.

A) pyridoxamine
B) niacin
C) riboflavin
D) cobalamin
E) pantothenic acid

Question 20

Which lipoprotein particle transports triacylglycerols from the intestine?

A) chylomicron
B) very low density lipoprotein
C) intermediate density lipoprotein
D) low density lipoprotein
E) high density lipoprotein

Question 21

How are fatty acids larger than 16 carbons formed?

A) By elongation reactions catalyzed by enzymes on the endoplasmic reticulum
B) By one-carbon additions at the mitochondrial membrane
C) By elongation reactions catalyzed by enzymes in the peroxisomes
D) By addition of acetoacetyl CoA
E) None of the answers is correct.

Question 22

Which of the following activates fatty acid synthesis?

A) malonyl CoA
B) glucagon
C) phosphorylation of acetyl CoA carboxylase
D) citrate
E) None of the answers is correct.

Question 23

The hormone __________ induces lipolysis, whereas the hormone __________ inhibits the process.

A) epinephrine; adrenocorticotropic hormone
B) glucagon; insulin
C) insulin; norepinephrine
D) glucagon; epinephrine
E) epinephrine; glucagon

Question 24

What are the similarities between fatty acid synthesis and degradation?

Question 25

Why is the anhydrous nature of triacylglycerols important in energy efficiency?

Question 26

Why are triacylglycerols an excellent design for energy stores?

A) They are anhydrous.
B) They are small.
C) They are highly reduced.
D) They are anhydrous, and they are small.
E) They are anhydrous, and they are highly reduced.

Question 27

What are four physiological roles for fatty acids?

Question 28

The $\beta$ oxidation of myristyl-CoA (C-14:0) yields

A) 7 acetyl-CoA + 7 FADH₂ + 7 NADH + 7 H⁺.
B) 6 acetyl-CoA + 7 FADH₂ + 7 NADH + 7 H⁺.
C) 7 acetyl-CoA + 6 FADH₂ + 6 NADH + 6 H⁺.
D) 7 acetyl-CoA + 7 FAD + 7 NAD⁺.
E) 14 acetyl-CoA + 12 FADH₂ + 12 NADH + 12 H⁺.

Question 29

Briefly outline the steps in fatty acid degradation.

Question 30

What is the committed step in fatty acid synthesis?

A) binding of the fatty acyl group to the acyl carrier protein
B) synthesis of malonyl CoA
C) transacylase reaction
D) the formation of acetoacetyl-ACP
E) None of the answers is correct.

Question 31

Enzymes that digest the triacylglycerols into free fatty acids and monoacylglycerol are called

A) hydrases.
B) glyases.
C) lipases.
D) lyases
E) None of the answers is correct.

Question 32

How is acetyl CoA carboxylase regulated globally?

A) By formation of inactive fibers
B) By the enzyme being switched off by phosphorylation and activated by dephosphorylation
C) By zymogen activation
D) By the binding of cAMP
E) None of the answers is correct.

Question 33

How does fatty acid oxidation differ in peroxisomes?

A) The final product is not acetyl CoA but is succinyl CoA.
B) NAD⁺ does not participate in the pathway.
C) The initial dehydrogenation reaction is different in that electrons are transferred to O₂ to yield H₂O₂.
D) All oxidations use NAD⁺ as the oxidizing agent.
E) None of the answers is correct.

Question 34

Fatty acids are the building blocks of

A) cholesterol.
B) phospholipids.
C) glycolipids.
D) cholesterol and phospholipids
E) All the answers are correct.

Question 35

The function of the enzyme acyl CoA synthetase is

A) lipolysis to release free glyceraldehyde.
B) ATP-dependent reduction prior to activation.
C) ATP-dependent activation of fatty acids using CoA.
D) Production of acetyl CoA for the TCA cycle
E) None of the answers is correct.

Question 36

Describe the processes that dietary triacylglycerols must go through to be absorbed by intestines and transported in the blood stream.

Question 37

What organs or tissues prefer to use ketone bodies such as acetoacetate as a fuel energy source instead of glucose?

A) heart muscle
B) skeletal muscle
C) brain
D) pancreas
E) None of the answers is correct.

Question 38

How many rounds of $\beta$ oxidation would be required for a 16-C fatty acyl chain to be degraded completely to acetyl-CoA?

A) 7
B) 8
C) 15
D) 16
E) None of the answers is correct.

Question 39

Coenzyme(s) involved in the degradation of saturated fatty acyl CoA include(s)

A) FAD.
B) NAD⁺.
C) TPP.
D) FAD and NAD⁺.
E) All the answers are correct.

Question 40

What types of reactions do cobalamin enzymes catalyze?

A) intramolecular rearrangements
B) methylations
C) reduction of ribonucleotides to deoxyribonucleotides
D) intramolecular rearrangements and reduction of ribonucleotides to deoxyribonucleotides
E) All the answers are correct.

Question 41

In odd-numbered fatty acid chains, how is the final 3-carbon piece, propionyl CoA, utilized? What unusual coenzyme is necessary for this process?

Question 42

Explain this statement: "Fats burn in the flame of carbohydrates."

Question 43

What pathological conditions can arise from a large increase in blood levels of ketone bodies in diabetics?

Question 44

How is pyrophosphate formation an important theme in biochemistry?

Question 45

Describe the three stages required for other tissues (for example muscle cells) to utilize the energy stored in adipocytes.

Question 46

How are unsaturated fatty acids degraded?

Question 47

What is the role of the acyl carrier protein in fatty acid synthesis?

Question 48

Calculate the amount of ATP generated from the total oxidation of an unactivated fatty acid with an acyl chain of 16 carbons.

Question 49

What is the fate of glycerol released during lipolysis?

Question 50

Explain why animals are unable to convert fatty acids to glucose.