Deck 25: The Organic Chemistry of Lipids

Question 1

What is the IUPAC name for isoprene?

A)1,3-pentadiene
B)2,4-pentadiene
C)2,3-dimethyl-1,3-butadiene
D)2-methyl-1,3-butadiene
E)none of the above

Answer 1

2-methyl-1,3-butadiene

Question 2

Myristic acid has the formula CH₃(CH₂)₁₂CO₂H.Provide the structure of the triglyceride trimyristin.

Answer 2

Question 3

Identify the compound that would be formed from the hydrogenation of linolenic acid.

A)palmitic acid
B)lauric acid
C)stearic acid
D)myristic acid
E)linoleic acid

Answer 3

stearic acid

Question 4

The C:H ratio present in most terpenes is

A)1:2
B)2:3
C)1:3
D)3:8
E)5:8

Question 5

Which of the following terms best describes the compound below? CH₃(CH₂)₁₂CO₂H

A)a fatty acid
B)an oil
C)a wax
D)a soap
E)a phosphatidic acid

Question 6

Which of the following terms best describes the compound below?

A)a steroid
B)an unsaturated triglycaride
C)a soap
D)a complex lipid
E)a terpene

Question 7

Which of the following statements is true about terpenes?

A)They are a class of lipids that can be isolated from plants.
B)They contain carbon atoms in multiples of five.
C)They are composed of isoprene units joined together in a head-to-tail fashion.
D)Tetraterpenes have 40 carbon atoms.
E)all of the above

Question 8

Which of the following terms best describes the compound below? CH₃(CH₂)₇CH CH(CH₂)₇CO₂H

A)an unsaturated fatty acid
B)a triglyceride
C)a synthetic detergent
D)a micelle
E)isoprene

Question 9

How many isoprene units are in β-carotene?

A)4
B)5
C)6
D)7
E)8

Question 10

Identify the compound with the highest melting point.

A)palmitic acid
B)lauric acid
C)stearic acid
D)myristic acid
E)linoleic acid

Question 11

Why do most naturally occurring fatty acids contain an even number of carbon atoms?

Question 12

Which of the following statements is true for both cholesterol and vitamin A?

A)Both are vitamins.
B)Both are proteins.
C)Both are lipids.
D)Both are steroids.
E)Both are fatty acids.

Question 13

How many isoprene units are in a sesquiterpene?

A)1
B)2
C)3
D)4
E)5

Question 14

A terpene is believed to have one of the structures below.Based on the isoprene rule,which structure is more likely.Explain your reasoning.

Question 15

Which of the following statements is not true about fatty acids?

A)Fatty acids are carboxylic acids with long hydrocarbon side chains.
B)The double bonds in unsaturated fatty acids are always conjugated.
C)Most naturally occurring fatty acids contain even numbers of carbons and are unbranched.
D)Fatty acids can be saturated or unsaturated.
E)Physical properties of fatty acids depend on the length of the hydrocarbon chain and the degree of unsaturation.

Question 16

Which of the following is the major components of cell membranes?

A)phosphoglycerides
B)sphingosine
C)squalene
D)prostaglandins
E)terpenes

Question 17

What organic compounds are formed when linoleic acid,CH₃(CH₂)₄CH CHCH₂CH CH(CH₂)₇CO₂H,is ozonolyzed and subsequently treated with H₂O₂?

Question 18

Which of the following fatty acids cannot be synthesized by mammals but must be included in the diet because it is needed to synthesize arachidonic acid which in turn will synthesize prostaglandins?

A)lauric acid
B)palmitic acid
C)arachidic acid
D)linoleic acid
E)oleic acid

Question 19

Palmitic acid (hexadecanoic acid)has a melting point of 63°C.Palmitoleic acid (9-hexadecenoic acid)has a melting point of 32°C.Explain this difference in melting points.

Question 20

Which of the following best explains why the melting points of saturated fats increase with increasing molecular weight?

A)decreased polarity
B)decreased hydrogen bonding
C)increased hydrogen bonding
D)decreased intermolecular van der Waal's interactions
E)increased intermolecular van der Waal's interactions

Question 21

The following molecule represents a

A)phosphoglyceride.
B)terpene.
C)squalene.
D)prostaglandin.
E)steroid.

Question 22

Most hormones are

A)phosphoglycerides.
B)terpenes.
C)squalenes.
D)prostaglandins.
E)steroids.

Question 23

What is the most abundant steroid in our body?

A)cholesterol
B)aldosterone
C)hydrocortisone
D)estradiol
E)prostaglandin

Question 24

The five-carbon compound used for the biosynthesis of terpenes is called isopentenyl pyrophosphate.Which of the following is the structure of isopentenyl pyrophosphate?

A)I
B)II
C)III
D)IV
E)V

Question 25

Which of the following is not an intermediate in the biosynthesis of isopentenyl pyrophosphate?

A)hydroxymethylglutaryl-CoA
B)mevalonylphosphate
C)acetoacetyl-CoA
D)dimethylallyl phosphate
E)mevalonic acid

Question 26

What is the precursor of bile acids?

A)phosphoglyceride
B)acetyl CoA
C)squalene
D)prostaglandin
E)cholesterol

Question 27

In nature,biosynthesis of cholesterol starts from

A)phosphoglyceride.
B)amino acids.
C)squalene.
D)prostaglandin.
E)steroid

Question 28

Squalene is a

A)monoterpene.
B)sesquiterpene.
C)diterpene.
D)triterpene.
E)carotenoid.

Question 29

The following molecule represents a

A)phosphoglyceride
B)terpene
C)squalene
D)prostaglandin
E)steroid

Question 30

Provide the structure of α-farnesene,a simple,acyclic sesquiterpene.

Question 31

In the rod cells of the eye,retinol (vitamin

A)can be oxidized and then isomerized into an aldehyde and a cis double bond at C-11 to form a molecule called 11Z-retinal.Propose a structure for 11Z-retinal.

Question 32

β-carotene is a

A)monoterpene.
B)sesquiterpene.
C)diterpene.
D)triterpene.
E)tetraterpene.

Question 33

Propose a mechanism for the reaction,of dimethylallyl pyrophosphate with isopentenyl pyrophosphate to form geranyl pyrophosphate.

Question 34

Circle the isoprene units present in menthol below.

Question 35

Lycopene is a

A)monoterpene.
B)sesquiterpene.
C)diterpene.
D)triterpene.
E)tetraterpene.

Question 36

Which of the following is involved in the biosynthesis of vasoconstrictor,thromboxane?

A)phosphoglycerides
B)sphingosine
C)squalene
D)PGH₂
E)cholesterol

Question 37

Biosynthesis of terpenes start from

A)phosphoglyceride.
B)acetyl CoA.
C)squalene.
D)prostaglandin.
E)cholesterol.