Deck 24: Lipids

Question 1

Triglycerides are esters of fatty acids and:

A)

B)

C)

D)

Answer 1

Question 2

Which of the following reagents can be used for the saponification of a fat or oil?

A) $\mathrm{H}_{2}, \mathrm{Ni}$
B) $\mathrm{LiAlH}_{4}$ followed by $\mathrm{H}_{2} \mathrm{O}$
C) $\mathrm{H}_{2} \mathrm{O}, \mathrm{NaOH}$
D) $\mathrm{H}_{2} \mathrm{O}, \mathrm{HCl}$

Answer 2

$\mathrm{H}_{2} \mathrm{O}, \mathrm{NaOH}$

Question 3

Which of the following has the highest melting point?

A. $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{CO}_{2} \mathrm{H}$
B. $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CH}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CO}_{2} \mathrm{H}($ cis $)$
C. $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CO}_{2} \mathrm{H}$ (cis, cis $)$
D. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CO}_{2} \mathrm{H}$ (cis, cis, cis)

A) A
B) B
C) C
D) D

Answer 3

A

Question 4

In the synthesis of fatty acids, what is the next step in the reaction of S-acetoacetyl acyl carrier protein?

A) reduction with NADPH
B) oxidation with $\mathrm{NADP}^{+}$
C) alkylation at C-2
D) condensation with $\mathrm{CH}_{3} \mathrm{CO}-\mathrm{S}-\mathrm{ACP}$

Question 5

Waxes are

A) esters of unbranched long-chained fatty acids and unbranched long-chained alcohols.
B) esters of steroids.
C) polymers of isoprene units.
D) esters of unbranched long-chained fatty acids and glycerol.

Question 6

Terpenes are formed from "isoprene units." What is the structure of isoprene?

A)

B)

C)

D)

Question 7

Which one of the following is an important function of the pyrophosphate group in isoprenoid biosynthesis?

A) to be an acid catalyst for terpene synthesis
B) to provide a good leaving group for terpene synthesis
C) to act as a nucleophile for terpene synthesis
D) to provide resonance stability for terpene synthesis

Question 8

Prostaglandins are biosynthesized from

A) terpenes.
B) steroids.
C) fatty acids.
D) carbohydrates.

Question 9

Lanosterol (the precursor of steroids) is biosynthesized from the triterpene

A) $\beta$ -carotene.
B) caryophyllene.
C) $\alpha$ -farnesene.
D) squalene.

Question 10

Farnesol, shown below, is biosynthesized from three isoprene units. Identify where the isoprene units are connected.

A) C-3 to C-4 and C-7 to C-8
B) C-4 to C-5 and C-8 to C-9
C) C-4 to C-5 and C-9 to C-10
D) C-5 to C-6 and C-9 to C-10

Question 11

Which of the following fatty acids is most reactive to free radical oxidations with $\mathrm{O}_{2}$ or $\bullet \mathrm{OH}$ ?

A) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{CO}_{2} \mathrm{H}$
B) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CH}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CO}_{2} \mathrm{H}$
C) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{7} \mathrm{CO}_{2} \mathrm{H}$
D) All have approximately the same reactivities with $\mathrm{O}_{2}$ and $\bullet \mathrm{OH}$ .

Question 12

Saponification of a triglyceride with aqueous sodium hydroxide gives

A) glycerol and the sodium salts of long-chained fatty acids.
B) glycerol and long-chained alcohols.
C) sodium acetate and long-chained alcohols.
D) sodium acetate and long-chained fatty acids.

Question 13

Which of the following reactions isomerizes cis double bonds to trans double bonds in fats and oils?

A) saponification with $\mathrm{H}_{2} \mathrm{O}, \mathrm{NaOH}$
B) hydrogenation with $\mathrm{H}_{2} / \mathrm{Ni}$
C) ozonolysis with $\mathrm{O}_{3}$
D) reduction with $\mathrm{LiAlH}_{4}$