Deck 19: Lipids

Question 1

The key step in the preparation of soap, saponification, is best described by which mechanism?

A) base catalyzed acyl addition
B) electrophilic addition
C) acid catalyzed acyl substitution
D) base catalyzed acyl substitution

Answer 1

base catalyzed acyl substitution

Question 2

Which is not a characteristic group in phospholipids?

A) phosphate esters
B) fatty acid esters
C) glycerides
D) polyamides

Answer 2

polyamides

Question 3

Fats, oils, phospholipids, prostaglandins and steroids have which properties in common?
I. oxygen functionality
II. nonpolar groups
III. rings
IV. unsaturation

A) I, II
B) III, IV
C) I, III
D) II, IV

Answer 3

I, II

Question 4

Which properties are characteristic of the most abundant fatty acids found in plants and animals?
I. They contain an even number of carbon atoms, in the range 10-19.
II. The cis isomer predominates.
III. The unsaturated fatty acids have higher melting points than the corresponding saturated acids.
IV. The most abundant fatty acids are lauric, myristic and linolenic.

A) I, II
B) III, IV
C) I, III
D) II, IV

Question 5

Which property of phospholipids accounts for their ability to form fluid membranes?

A) nonpolarity
B) unsaturation
C) hydrophilicity and lipophilicity
D) lipophilicity

Question 6

Which structure is a cortisone?

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

Question 7

The fluid-mosaic model of the lipid bilayer states:

A) lipids coexist side by side as discreet units and proteins float in the bilayer, able to move along the plane of the membrane.
B) the lipids form new covalent bonds between chains and lock the proteins into position, much like a mosaic tile.
C) the lipids form a fluid-like membrane that metabolic components (the mosaic) can freely cross.
D) the lipid bilayer forms a rigid structure with channels that allow fluid to pass.

Question 8

Which are the most common fatty acids found in phospholipids?

A) palmitoleic, stearic, lauric
B) lauric, myristic, palmitic
C) palmitic, stearic, oleic
D) stearic arachidic, oleic

Question 9

Soap is an anionic surfactant used in conjunction with water for washing and cleaning. It is a typical example for European Medieval technology. Animal or plant fats are hydrolyzed by the strong base (NaOH in water, usually called lye), yielding alkali salts of fatty acids and glycerol. Historically, tallow (beef or mutton fat) is used for saponification. Tallow contains glycerol esters of oleic acid (47%), palmitic acid (26%) and stearic acid (14%). What are the chemical components of soap from tallow?

A) I, II, III
B) II, III, IV
C) I , III, V
D) III, IV, V, VI

Question 10

Which saturated fatty acids have the correct name?
I. CH₃(CH₂)₁₀COOH - stearic acid
II. CH₃(CH₂)₁₄COOH - palmitic acid
III. CH₃(CH₂)₁₆COOH - lauric acid
IV. CH₃(CH₂)₁₈COOH - arachidic acid

A) I, II
B) III, IV
C) I, III
D) II, IV

Question 11

Which is the structure of a phosphatidyl choline?

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

Question 12

Deposits and films are a problem with soaps but not detergents because of which property?

A) Soaps form soluble calcium salts.
B) Detergents form more stable micelles.
C) Most detergents do not form insoluble calcium salts.
D) Soap micelles are unstable in acid.

Question 13

Polysorbate 80 (Tween 80) is a non-ionic surfactant and emulsifier (w+x+y+z=19). A typical application is in ice cream, where it hinders the milk proteins from completely coating the fat droplets. This allows for a firmer texture, which is associated with high quality ice cream. Which of the following statements is true? I) Polysorbate 80 is an ester.
II) Polysorbate 80 has a hydrophilic component.
III) Polysorbate 80 has a hydrophobic component.
IV) Polysorbate 80 forms micelles above its critical micellar concentration.

A) I and II
B) II and III
C) I, II, and IV
D) all of the above

Question 14

Which reagents could be used to harden an oil to a fat?

A) NaBH₄ / H₂O
B) Ni / H₂
C) Ag(NH₃)₂⁺ / H₂O
D) Cu²⁺ / buffer

Question 15

Which physical property of triacylglycerols rich in unsaturated fatty acids is responsible for the lower melting point than the corresponding saturated compounds?

A) Hydrophobic attractions
B) Hydrophilic interactions
C) Cis-carbon-carbon double bond steric interactions
D) Hydrogen bonding

Question 16

Today, palm oil or palm kernel oil is often used for the production of soap. The main components of palm kernel oil are glycerol esters of lauric acid (48%), myristic acid (16%) and palmitic acid (14%). What are the chemical components of soap from palm kernel oil?

A) I, II, III
B) III, IV, V
C) III, IV, VI
D) IV, V, VI

Question 17

Which physical property of triacylglycerols rich in saturated fatty acids is responsible for the higher melting point than the corresponding unsaturated compounds?

A) Dispersion forces
B) Hydrophilic interactions
C) Cis-carbon-carbon double bond steric interactions
D) Hydrogen bonding

Question 18

Which property of phospholipids accounts for their ability to form micelles?

A) nonpolarity
B) unsaturation
C) hydrophilicity and lipophilicity
D) lipophilicity

Question 19

How many triglycerides, including stereoisomers, are possible if two fatty acids are present in the triglyceride?

A) 3
B) 4
C) 5
D) 8

Question 20

What is the pH of a solution of an anionic detergent (typically: a soap or laundry detergent) (I), a non-ionic detergent (typically: an emulsifier in drink preparations) (II) and a cationic detergent (typically: a fabric softener) (III)?

A) I: acidic, II: neutral, III: basic
B) I: basic, II: neutral, III: acidic
C) I: basic, II: neutral, III: neutral
D) I: acidic, II: basic, III: neutral

Question 21

Which is the best description of the first step (A) of the biosynthesis of prostaglandin?

A) hydration
B) reduction
C) oxidation
D) Claisen condensation

Question 22

What do all prostaglandins have in common?
I. Prostaglandins are only biosynthesized in males.
II. All prostaglandins feature 19 carbon atoms.
III. All prostaglandins are alkenes.
IV. All prostaglandins feature one carbocylic ring, but the size of the ring may vary.

A) I and III
B) II and IV
C) I and IV
D) II and III

Question 23

Order the four vitamins according to increasing fat-solubility (most hydrophilic first):

A) II, III, I, IV
B) IV, II, III. I
C) III, II. I. IV
D) I, II, III, IV

Question 24

Complete the reaction below by providing the missing products.

Question 25

The melting point order of the following fatty acids is (lowest to highest),
lauric (12:0) palmitic (16:0) palmitoleic (16:1) oleic (18:1)
_______ _______ _______ ______

Question 26

Complete the structure of the alkylbenzene sulfonate detergent below.

Question 27

Fluoxymesterone is an anabolic steroid with strong androgenic properties, which has been used for the treatment of hormone-sensitive breast tumors in women. It is also misused as an aggression enhancer in boxing and martial arts competitions. Since the half-life of this hormone in the human body is more than 9h, it can be easily detected in a doping sample taken after the competition. Compare the in-vivo physical properties of both hormones. Which statements below are correct? I) The exchange of a hydrogen atom vs. a fluorine atom does not significantly change the water-solubility, because the C-F bond is short and an organically bound fluorine-atom is almost as small as a carbon-bonded hydrogen atom.
II) The exchange of a hydrogen vs. a fluorine atom does significantly change the water-solubility, because the C-F bond is non-polar covalent, whereas C-H is polar covalent.
III) The introduction of a second hydroxy-group at the C-ring of fluoxymesterone increases the water-solubility.
IV) Fluoxymesterone is less water soluble than testosterone, because it possesses 19 carbon atoms, compared to 19 of testosterone.

A) I and II
B) II and III
C) I and III
D) I, III, and IV

Question 28

Which is a prostaglandin?

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

Question 29

Which vitamins are soluble in lipids?

A) II and III
B) III and IV
C) I and III
D) II and IV

Question 30

Which statements about steroids are false?
I. The fusion of all rings is cis.
II. Sex hormones, adrenocorticoid hormones, bile acids and vitamin D are derived from
Cholesterol.
III. The biosynthesis of cholesterol produces several isomers.
IV. Steroids are tetracyclic ring systems

A) I, III
B) II, IV
C) I, II
D) III, IV

Question 31

Lauramide diethanolamine (lauramide DEA, the main component of cocamide DEA) is prepared by reacting lauric acid from coconut oil with diethanolamine. It is a viscous liquid and a typical foaming agent in shampoos and bath products. Complete the following sequence of reactions.

Question 32

Which is the best description of the second step (B) of the biosynthesis of prostaglandins?

A) hydration
B) reduction
C) oxidation
D) Claisen condensation

Question 33

Which natural products have structures derived from cholesterol?
I. vitamin A
II. vitamin D
III. cholic acid
IV. cortisone
V. squalene

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

Question 34

Which structure is vitamin A?

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

Question 35

Complete the structure of the phospholipid below.

Question 36

Which is the number of stereocenters in methandrostenolone?

A) 4
B) 6
C) 8
D) 10

Question 37

The lower melting point of unsaturated fatty acids compared to saturated fatty acids is due to ______________________________ differences.

Question 38

Which common structural feature of vitamin E and vitamin K₁ best accounts for the greater solubility of these molecules in organic solvents than water?

A) aromatic rings
B) oxygen atoms
C) 4 isoprene units
D) a quinone / hydroquinone units

Question 39

Which statements about vitamins are true?
I. Vitamins A, D, E and K are fat soluble.
II. Vitamins A, D, E and K are derived from cholesterol.
III. Vitamins A, D, E and K each contain 4 isoprene units.
IV. Vitamins A, D, E and K have distinct physiological activities.

A) II, III
B) III, IV
C) I, III
D) I, IV

Question 40

Shown are cholesterol, estradiol, testosterone (see N13) and progesterone, which is the female pregnancy hormone. Cholesterol and all three hormones are present in both, males and females, albeit in different concentration. Their biosynthesis follows one common scheme. Based on the structures shown below, which is the hormone that is formed as an intermediate during the biosynthesis of the other two hormones?

A) cholesterol
B) progesterone
C) estradiol
D) testosterone

Question 41

Human fat has more unsaturated fatty acids than plant fats.

Question 42

Bile acids are synthesized in the liver by cytochrome p450-mediated oxidation of cholesterol. They are often conjugated with the amino acid glycine and stored in the gallbladder. What are the differences in molecular structure between cholesterol and the cholic-acid conjugate shown below?

Question 43

What are the main structural differences between molecules of estradiol (the predominant sex hormone in females, albeit present in males at lower levels) and testosterone (the principal male sex hormone and an anabolic steroid albeit it is also synthesized by females)?

Question 44

Aldosterone is an androgen.

Question 45

Stearic acid is an unsaturated fatty acid.

Question 46

Vitamin A precursor $\beta$ -carotene belongs to the _____________ class of compounds and contains ________ isoprene units.

Question 47

Prostaglandin is a member of the _________________ class of compounds, which are synthesized from ____________________.

Question 48

The forces that drive micelle and lipid bilayer formation are the same.

Question 49

The forces which drive bilayer formation by phospholipids are __________________ and ________________.

Question 50

Vitamin D precursors have the cholesterol ring system.

Question 51

Why do ectothermic (cold-blooded) animals have significantly higher amounts of unsaturated fatty acids in their fatty acid signatures than endothermic (warm blooded) animals?

Question 52

There are several stereoisomers of cholesterol found in living systems.

Question 53

Dipalmitoylphosphatidylcholine (DPPC) is a phospholipid that is the major constituent of pulmonary surfactant. It is also used as a model phospholipid in numerous studies of liposomes, lipid bilayers and model biological membranes. Complete the following sequence of reactions.

Question 54

Vitamins A, D, E, and K are included in the lipid class because they are _______ soluble.

Question 55

Soaps and detergents form micelles when added to water.

Question 56

17- $\alpha$ -Ethinyl-estradiol is an orally bio-active estrogen used in almost all modern formulations of contraceptive pills. It is one of the most commonly used medications. Complete the following synthetic scheme:

Question 57

Prostaglandins are involved with the inflammatory response.

Question 58

Vitamin E is required for blood clotting.

Question 59

Androsterone has ________ stereocenters and ____________ possible stereoisomers.

Question 60

Soap micelles form in water by aggregating the negatively charged carboxylate groups toward the inside and the lipophilic carbon chains toward the outside of the micelle.