PROBLEMS CH 17

Learning CheckWhich lipids contain the alcohol glycerol?A. steroids and waxesB. triacylglycerols and glycerophospholipidsC. sphingolipids and glycerophospholipidsD. glycerophospholipids and waxes

SolutionWhich lipids contain the alcohol glycerol?A. steroids and waxesB. triacylglycerols and glycerophospholipidsC. sphingolipids and glycerophospholipidsD. glycerophospholipids and waxes

Answer is B. Triacylglycerols and glycerophospholipidscontain the alcohol glycerol.

Learning Check

Assign the melting point (mp) of −17°C, 13°C, or 69°C to each one of the following 18-carbon fatty acids, and list the fatty acids in order from highest to lowest melting point. Explain.A. oleic acidB. stearic acidC. linoleic acid

Solution

Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. Oleic acid, which has one double bond, has a higher mp than linoleic acid, which has two double bonds.

B. stearic acid mp 69°C saturatedA. oleic acid mp 13°C unsaturated with one

double bond C. linoleic acid mp −17°C unsaturated with two

double bonds

Learning CheckDraw the condensed structural formulas for each of the fatty acids with 10 carbon atoms that follow.

A. saturated

B. monounsaturated omega-3

C. monounsaturated omega-6

SolutionDraw the condensed structural formulas for each of the fatty acids with 10 carbon atoms that follow.A. saturated CH3—CH2—CH2—CH2—CH2—CH2—CH2—CH2—CH2—COOH

B. monounsaturated omega-3

C. monounsaturated omega-6

Learning Check

What are the fatty acids in the following triacylglycerol?

CH2 (CH2)12 CH3

CH2

CH CH CH (CH2)7 CH3O (CH2)7C

O

O (CH2)16 CH3C

O

O

O

C

Solution

Stearic acid

Oleic acid

Myristic acidCH2 (CH2)12 CH3

CH2

CH CH CH (CH2)7 CH3O (CH2)7C

O

O (CH2)16 CH3C

O

O

O

C

Learning CheckDraw the condensed structural formula for glyceryl tripalmitoleate (tripalmitolein).

SolutionDraw the condensed structural formula for glyceryl tripalmitoleate (tripalmitolein).

Which of the following products is obtained from the complete hydrogenation of glyceryl trioleate?

B. glyceryltristearate

Solution

Olestra, a Fat Substitute

Olestra is • used in foods as an artificial fat.• composed of 6–8 long-chain fatty acids attached

by ester links to a sucrose (not glycerol) molecule.• not broken down in the intestinal tract.

Learning Check

Identify each statement as true (T) or false (F).

A. There are more unsaturated fats in vegetable oils.

B. Vegetable oils have higher melting points than fats.

C. Hydrogenation of oils converts some cis-double bonds to trans-double bonds.

D. Animal fats have more saturated fats.

Solution

Identify each statement as true (T) or false (F).

T A. There are more unsaturated fats in vegetable oils.

F B. Vegetable oils have higher melting points than fats.

T C. Hydrogenation of oils converts some cis-double

bonds to trans-double bonds.

T D. Animal fats have more saturated fats.

What products are obtained from the complete hydrolysis of glyceryl trioleate?A. glycerol and 3 oleic acidsB. glyceryl tristearateC. glycerol and 3 stearic acids

Learning Check

What products are obtained from the complete hydrolysis of glyceryl trioleate?A. glycerol and 3 oleic acids

Solution

Learning Check

Draw the condensed structural formula of theproduct of the following reaction.

O

O

CH2

O

O

CH

CH2 O

O

C

C

C

(CH2)7 CH CH

CHCH(CH2)7

CHCH(CH2)7

(CH2)5 CH3

(CH2)5 CH3

(CH2)5 CH3

+ 3H2

Ni

Solution

CH2 (CH2)14

CH2

CH O C

O

O C

O

O

O

C

(CH2)14 CH3

(CH2)14 CH3

CH3

Learning Check

Identify each as a fatty acid, triacylglycerol, amino alcohol or glycerophospholipid.

A. glyceryl trioleate

B. cephalin

C. choline

D. palmitic acid

Solution

Identify each as a fatty acid, triacylglycerol, amino alcohol or glycerophospholipid. A. glyceryl trioleate triacylglycerol B. cephalin glycerophospholipid C. choline amino alcoholD. palmitic acid fatty acid

Learning CheckIdentify the components and type of

glycerophospholipid. O ║CH2—O—C— (CH2)16—CH3

O ║CH2—O—C— (CH2)16—CH3

+

O NH3 ║ │CH2—O—P—O—CH2—CH−COO –

│ O–

SolutionIdentify the components and type of glycerophospholipid. O ║CH2—O—C— (CH2)16—CH3

O 2 Stearic acids ║CH2—O—C— (CH2)16—CH3

+

O NH3 ║ │ Type = cephalinCH2—O—P—O—CH2—CH−COO –

│ Serine O– Phosphate Amino alcohol

Learning Check

Match the components of the cholesterol molecule with

each of the following: alkyl chain hydroxyl group steroid nucleus methyl group

CH3

CH3CH3

CH3

HO

CH3

AC

B

D

Solution

Match the components of the cholesterol molecule with

each of the following: alkyl chain hydroxyl group steroid nucleus methyl group

CH3

CH3CH3

CH3

HO

CH3

AC

B

D

D A

C B

Learning Check

Identify each of the following as a steroid, triacylglycerol, phospholipid, or sphingolipid.A. cholesterolB. glycerol, 2 fatty acids, phosphate, and cholineC. glyceryl tristearateD. sphingosine, fatty acid, phosphate, and cholineE. estradiolF. bile saltsG. lipids in plasma membranes

Solution

A. cholesterol steroidB. glycerol, 2 fatty acids, phospholipid

phosphate, and cholineC. glyceryl tristearate triacylglycerol D. sphingosine, fatty acid, sphingolipid

phosphate, and cholineE. estradiol steroidF. bile salts steroidG. lipids in plasma phospholipid

membranes sphingolipid

Learning CheckWhat is the transport of particles across a cell

membranefrom high concentration to low concentration called?A. facilitated transportB. diffusion (passive transport)C. active transport

SolutionWhat is the transport of particles across a cell

membranefrom high concentration to low concentration called?A. facilitated transportB. diffusion (passive transport)C. active transport