Deck 17: Lipid Metabolism

Question 1

Of the major lipoproteins, _____ are highest in cholesterol and cholesterol esters while _____ are highest in triacylglycerols.

A) chylomicrons; HDL
B) VLDL; LDL
C) LDL; VLDL
D) LDL; chylomicrons
E) HDL; VLDL

Answer 1

LDL; chylomicrons

Question 2

In the $\beta$ -oxidation pathway, the oxidation occurs at carbon _____ with the acetyl group that becomes acetyl-CoA derived from the _____ end of the fatty acid.

A) 1; carbonyl
B) 1; methyl
C) 2; carbonyl
D) 2; methyl
E) 3; carbonyl

Answer 2

3; carbonyl

Question 3

During $\beta$ -oxidation in the peroxisome, what reoxidizes the enzyme-bound FADH₂ during the first oxidation of the pathway?

A) H₂O₂
B) O₂
C) NAD⁺
D) FMN
E) none of the above

Answer 3

O₂

Question 4

The portion of the acyl carrier protein that activates the growing fatty acid is similar to the structure of _____.

A) biotin
B) thiamine pyrophosphate
C) tetrahydrobiopterin
D) coenzyme A
E) folic acid

Question 5

What molecule is able to move across the mitochondrial membrane and is thus used to "transfer" acetyl-CoA from the mitochondria to the cytosol?

A) acetate
B) oxaloacetate
C) $\alpha$ -ketoglutarate
D) citrate
E) succinate

Question 6

In fatty acid synthesis, _____ catalyzes the reverse reaction of _____ in $\beta$ -oxidation.

A) 3-ketoacyl-ACP synthase; acyl-CoA dehydrogenase
B) 3-ketoacyl-ACP reductase; 3-hydroxyacyl-CoA dehydrogenase
C) 3-hydroxyacyl-ACP dehydrase; enoyl-CoA hydratase
D) enoyl-ACP reductase; thiolase
E) transacylase; enoyl-CoA hydratase

Question 7

When a growing fatty acid is not attached to the ACP, it is attached to a _____ residue of the fatty acid synthase complex.

A) Cys
B) Ser
C) Tyr
D) Glu
E) His

Question 8

What are the energy requirements for the synthesis of one molecule of palmitate from eight molecules of acetyl-CoA in the mitochondria?

A) 16 NADPH, 15 ATP
B) 16 NADPH, 8 ATP
C) 16 NADPH, 7 ATP
D) 14 NADPH, 15 ATP
E) 14 NADPH, 7 ATP

Question 9

What enzymes are required to make fatty acids containing 22 or 24 carbons?

A) elongases
B) reductase
C) desaturase
D) hydratase
E) malonyl-CoA ligase

Question 10

What mechanism is used to control whether HMG-CoA is used for ketone body synthesis or for cholesterol synthesis?

A) control of HMG-CoA lyase versus HMG-CoA reductase
B) control of NADPH versus acetyl-CoA levels
C) control of NADPH:NAD⁺ levels
D) depletion of products influences where HMG-CoA will be shunted
E) ketone bodies are synthesized in the mitochondria; cholesterol is synthesized in the cytoplasm

Question 11

A ___ becomes a ___ through loss of cholesterol to tissue.

Question 12

The movement of ___ into a cell occurs by endocytosis following ___.

Question 13

Considering the characteristics of common fatty acids found in animals described in the text, which of the structures shown below would you consider the rarest fatty acid if found in animals?

A)
B)

C)
D)
E) All structures would be equally rare.