chapters 11-12

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Triglycerides composed of glycerin and mostly polyunsaturated fatty acid residues are likely to be ___ at room temperature.

a. solid fats

b. liquid oils

c. gases

d. waxes


Shown below is the structure of the fatty acid, lauric acid: The boxed portion is considered to be both

a. hydrophilic and hydrophobic.

b. polar and hydrophobic.

c. polar and hydrophilic.

d. nonpolar and hydrophilic.


The structure of the fatty acid, palmitic acid, is

Palmitic acid is a(n) ___ fatty acid.

a. saturated

b. monounsaturated

c. polyunsaturated

d. waxy


Lecithin is found in egg whites and can be used as an emulsifying agent to keep mayonnaise from separating. Lecithin is classified as a ___.Select one:

a. phospholipid

b. wax

c. steroid

d. glycolipid


Animal fats and vegetable oils become rancid when exposed to air because

they are hydrogenated to form saturated fatty acids.

b. carbon-carbon double bonds are oxidized in air, producing small organic molecules.

c. they form amino acids in air.

d. they are partially hydrogenated.


Which enzyme is involved in the conversion of arachidonic acid into prostaglandins and thromboxanes in the body?

a. rybozymes

b. cyclooxygenase

c. transferases

d. isomerases


Sphingomyelins are found in ___.

a. waxes

b. egg whites

c. skin cells

d. nerve cell membranes


Cholesterol contains nonpolar rings and hydrocarbon chains, and also has an alcohol group (–OH). Which statement below is correct?

a. The molecule is totally hydrophobic.

b. Most of the molecule is hydrophobic with the –OH being hydrophilic.

c. The molecule is totally hydrophilic.

d. Cholesterol molecules would line up with the alcohol group attracted by the rings.


The structure below is best classified as a ___.

a. triglyceride

b. wax

c. steroid

d. phospholipid


Which of the following is released from the gallbladder into the small intestine to aid digestion by dispersing dietary lipids into fine emulsions?

a. Bile salts

b. cholesterolc. eicosanoidsd. phospholipids


The skeletal structure of docosahexaenoic acid, an essential fatty acid, is provided below. Docosahexaenoic acid is best classified as:

a. Omega-3-fatty acid

b. Omega-6-fatty acid

c. Saturated fatty acid

d. Wax


Identify the class of lipid to which the following molecule belongs.

a. sphingophospholipid

b. triglyceride

c. cholesterol

d . glycerophospholipid


Anabolic steroids can cause some serious health problems including

a. reduced circulation to the brain and liver.

b. muscle atrophy and blocked arteries.

c. high blood pressure and testicular atrophy.

d. the interruption of nerve impulses and reduced intestinal function.


Eicosanoids are hormones derived from arachidonic acid. Which is not an eicosanoid?

a. prostaglandin

b. leukotriene

c. progesterone

d. thromboxane


Which of the following is one of the products formed when the lipid below is saponified?



What is the function of nonsteroidal anti-inflammatory drugs (NSAID)?

a. To interrupt the production of prostaglandins from arachidonic acid.

b. To interfere with the production of anabolic steroids.

c. To facilitate the production of cyclooxygenase.

d. To stimulate the production of leukotrienes.


Sphingolipids are a class of phospholipids.



The lipid that is a cell surface receptor for hormones and drugs is aSelect one:

a. glycerophopholipid.

.b. ganglioside.

c. sphingomyelin.

d. cerebroside.


The glycolipid molecule is characterized by having a specific residue attached to the backbone. Which is that residue?

a. phosphate

b. glycerol

c. lipid

d. sugar


The ___ is the location on the protein molecule where enzyme catalyzed reactions take place.

a. substrate

b. zymogen

c. active site

d. coenzyme


What is the net charge on the oligopeptide in the figure shown here at pH 1?

a. 3+

b. 1+

c. 2+

d. 0


A certain enzyme's name is glucose-6-phosphorylase. This enzyme most likely catalyzes a reaction that

a. converts glucose into six phosphorous atoms.

b. synthesizes six glucose molecules.

c. joins six glucose molecules to a phosphate.

d. places a phosphate on the sixth carbon of glucose.


What level of protein structure is not disturbed by denaturing?

a. tertiary structure

b. primary structure

c. secondary structure

d. quaternary structure


Shown here is the amino acid glycine at a pH of ___.

a. 1 (no negative 1 +)

b. 7

c. 14

d. both 1 and 14


If an amino acid is in a neutral solution, the form the carboxyl group takes is ___.

a. —CO2–

b. —CO2H+

c. —CO2

d. —CO2H


Which of the following substances recognized by immune system evoke production of one or more antibodies?

a. secondary proteins

b. antigens

c. globular proteins

d. glycolipids


Aspartic acid is classified as a polar-acidic amino acid due to

a. the —CH group to which the amide group is attached.

b. the —CH2 group in the middle of the side chain.

c. the amide group located on a side chain.

d. the carboxyl group located on the side chain.


Which is a means of denaturing a protein?

a. changes in temperature

b. changes in pH

c. use of detergents or soaps

d. all of these choices


The peptide bond that connects amino acids in proteins is actually an ___ linkage.

a. amineb

b. amide

c. ether

d. ester


What form does isoleucine take at pH 14?



Which of the following sentences is true?

a. Rearranging the amino acid residues in a peptide or protein changes its function.

b. In an α-helix form, portions of polypeptide chain line up side by side with hydrogen bonds holding neighboring strands of sheet together.

c. The order of amino acid residues in a protein is referred to as its tertiary structure.

d. The overall three-dimensional shape of a protein is referred to as its primary structure.


An inhibitor is a substance that affects an enzyme by

a. reducing the ability to act as a catalyst.

b. removing the prosthetic group from an enzyme.

c. reacting with the enzyme so there is less effect of the chemical reaction’s surroundings on the rate of reaction.

d. stopping the separation of the enzyme from the product keeping the reaction from going to completion.


he structure of the dipeptide, Phe-Gly, in a solution of pH 14 is ___.



Protein molecules with the appropriate structure to be biologically active are native molecules.Select one:



Stereoisomers exist for most of the amino acids found in nature. Which statement below is correct?Select one:

Both the D-amino acids and the L- amino acids are used by living things.

b. Only the L-amino acids are incorporated in proteins.

c. A common conversion is from the D-amino acid to the L-amino acid.

d. L-amino acids are toxic.


Which of the following is an example of a protein that exhibits a quaternary structure?

a. insulin

b. hemoglobin

c. collagen

d. keratin


he α-helix and β-pleated sheet are both forms of the ___ structure of proteins.

a. primary

b. secondary

c. tertiary

d. quaternary


___ are inactive enzyme precursors that are synthesized, stored and may be activated where needed.

a. Substrates

b. Zymogens

c. Active sites

d. Coenzymes


Some proteins require more than one polypeptide chain to be biologically active. The level of protein structure involved is the ___ of a protein.

a. primary

b. secondary

c. tertiary

d. quaternary


Which of the following compounds share the steroid ring structure?

a. cholesterol and phospholipids

b. phospholipids and arachidonic acid

c. arachidonic acid and bile salts

d. bile salts and cholesterol


Sphingolipids are amphipathic hydrolysable lipids based on glycerol.



Testosterone is produced from arachidonic acid.



Which of the following lipids is not derived from cholesterol?

a. progesterone

b. thromboxane

c. cortisold

. testosterone


Oleic acid has the formula CH3(CH2)7(CH = CH(CH2)7CO2H. The carbon –carbon double bond in oleic acid is usually cis. Compared to saturated fatty acids with the same number of carbon atoms, cis-oleic acid will have

a lower melting point due to a kink in the hydrocarbon tail.

b. stronger London forces and a higher melting point.

c. bonds that fit in the packing of the hydrophobic tails, creating stronger interaction between molecules.

d. no reaction with hydrogen in the presence of platinum catalyst.


Waxes are compounds that are

a. the result of the reaction of a fatty acid and sodium hydroxide.

b. extremely hydrophilic due to the head end of the compound.

c. mixtures of water insoluble compounds, especially esters.

d. small compounds produced when short chain fatty acids react with an alcohol.


Trans fats are produced during the hydrogenation of fats and oils.



The fatty acid, palmitoleic acid, is

Notice the double bond. Palmitoleic acid is a ___ fatty acid.

a. saturated

b. monounsaturated

c. polyunsaturated

d. waxy


Omega-3 and Omega-6-fatty acids are essential fatty acids. Which of the following statement best describes these essential fatty acids?

a. They are very soluble in water.

b. They are saturated fatty acids that the body absorbs faster.

c. They are not produced in the body and must be obtained through diet.

d. They are waxes found in the body.


Fibrous proteins, because of their long fibers, tend to be soluble in water.



Hydrogen bonding plays a role in the primary structure of protein.



At physiological pH, most amino acids carry both a 1+ and 1- charge. This form is known as a ___.

a. zwitterion

b. anion

c. cation

d. isoelectric ion


he enzyme hexokinase catalyzes the transfer of a phosphate group from ATP to carbon #6 of D-glucose and other D-hexoses. L-hexoses are not substrates to the enzyme.

Hexokinase displays

a. relative specificity

b. stereospecificity

c. absolute specificity

d. both relative specificity and stereospecificity


The sequence of the amino acids in a protein is known as the ___ structure.

a. primary b. secondaryc. tertiaryd. quaternary


The net charge of peptides and proteins affects their solubility.



The overall three-dimensional shape of a protein is determined by its ___ and is known as the ___ structure of a protein.

a. amino acid residues/primary

b. amino acid residues/tertiary

c. isoelectric point/secondary

d. hydrogen bonding/secondary


In which solvent would lipids be most soluble?

a. hexane

b. water

c. methyl alcohol

d. ethyl alcohol


Which compounds are responsible for causing pain and inflammation?

a. anabolic steroids

b. adrenocorticoids

c. prostaglandins

d. leukotrienes


The effect of the hydrogenation of oils is to

. remove double bonds.

b. cause the oils to remain as liquids.

c. make the oils boil at a lower temperature.d. make the oils oxidize.


All commonly occurring fatty acids contain trans alkene groups.



The difference between the sphingolipids and the glycerophospholipids is that the sphingolipids

a. have three alcohol residues that replace the fatty acid residues.b. have one phosphate, but it is attached to the fatty acid residue, not the glycerol.c. have three phosphates, not one, and they are attached to all of the fatty acids.

d. include sphingosine with a phosphate attached to it, and an alcohol residue.


A contributing factor to the tertiary structure of a protein is a covalent bond between two atoms of ___.

a. sulfur

b. hydrogen

c. carbon

d. nitrogen


Where is the peptide bond located in this dipeptide?

a. the CO—NH joining serine and the valine

b. the doubly bonded oxygen just left of center between the amino acids

\c. the CH—CO on the top of the serine going to the rightd. the NH—CH between the serine and valine


Which is an α-amino acid?



The structures of the amino acids proline and glycine are shown below. Which of the following statements is true?

a. glycine is an α-amino acid, but proline is notb

b. both proline and glycine are chiral molecules

c. glycine is achiral and proline is chiral

d. proline exists as four enantiomers


Because amino acids contain polar covalent bonds, they are hydrophilic and will dissolve water.



The structure of palmitate ion derived from the fatty acid, palmitic acid, is

Its molecular structure has both polar and nonpolar portions. Therefore, palmitate ion is classified as ___.

a. hydrophobicb. lipophobicc. hydrophilic d . amphipathic

d . amphipathic


The hormone that is the starting point for the production of the adrenocorticoid hormones and testosterone is

a. progesterone.

b. estrogen.

c. cholesterol.

d. chylomicrons.


What kind of noncovalent interaction occurs between the –NH3 +
ending of one side chain of an amino acid with the –COOending of sidechain of another amino acid in tertiary structure of a protein?

a. salt bridge

b. hydrogen bonding

c. covalent disulfide bond

d. hydrophobic effect


Many of the chemical reactions of living things involve enzymes, which are

a. proteins that are in the form of parallel sheets.

b. proteins that catalyze reactions.

c. small DNA molecules.

d. denatured proteins.