Deck 18: Amino Acids and Proteins

Question 1

The reaction of amino acids to give peptides involves which pair of functional groups?

A)two amino groups
B)two carboxyl groups
C)an amino and a carboxyl group
D)a carboxyl and an alcohol group

Answer 1

an amino and a carboxyl group

Question 2

Polar R groups,along with acidic and basic R groups,are said to be ________ because they are attracted to water molecules.

A)hydrophilic
B)hydrophobic
C)ionized
D)unreactive
E)none of these

Answer 2

hydrophilic

Question 3

Serum albumin is an example of a(an)

A)enzyme.
B)structural protein.
C)storage protein.
D)transport protein.
E)protective protein.

Answer 3

transport protein.

Question 4

Two functional groups that are present in all amino acids are the ________ group and the ________ group.

A)hydroxyl; amide
B)carboxyl; amine
C)carboxyl; phosphate ester
D)acetal; amine
E)carbonyl; amide

Question 5

Which amino acid is a secondary amine with its nitrogen and the alpha-carbon joined as part of a ring structure?

A)arginine
B)glycine
C)histidine
D)lysine
E)proline

Question 6

Which amino acid is classified as basic?

A)valine
B)threonine
C)phenylalanine
D)lysine
E)glutamic acid

Question 7

The protein configuration that is primarily determined from interactions between R groups is the

A)primary structure.
B)secondary structure.
C)tertiary structure.
D)quaternary structure.
E)none of the above

Question 8

Non-polar R groups on amino acids are said to be ________ because they are not attracted to water molecules.

A)hydrophilic
B)hydrophobic
C)ionized
D)unreactive
E)none of these

Question 9

The side chains or R groups of amino acids can be classified into each of the following categories except

A)polar.
B)non-polar.
C)basic.
D)acidic.
E)isoelectric.

Question 10

An amino acid whose R group is predominantly hydrocarbon would be classified as

A)polar.
B)non-polar.
C)basic.
D)acidic.
E)isoelectric.

Question 11

Insulin is an example of a(an)

A)enzyme.
B)structural protein.
C)storage protein.
D)transport protein.
E)hormone.

Question 12

The peptide bond joining amino acids into proteins is a specific example of the ________ bond.

A)amide
B)carbonyl
C)ester
D)glycosidic
E)hydrogen

Question 13

Members of which class of biomolecules are the building blocks of proteins?

A)glycerols
B)monosaccharides
C)fatty acids
D)amino acids
E)nucleic acids

Question 14

All of the following are major functions of proteins except

A)transport of necessary chemicals.
B)protection against foreign substances.
C)support for organs or tissues.
D)control of biochemical reactions.
E)storage of energy.

Question 15

All of the following can be classified as biomolecules except

A)carbohydrates.
B)proteins.
C)lipids.
D)nucleic acids.
E)All of the above are biomolecules.

Question 16

Which category of amino acid contains R groups that are hydrophobic?

A)polar
B)non-polar
C)basic
D)acidic
E)basic and acidic

Question 17

Collagen is an example of a(an)

A)enzyme.
B)structural protein.
C)storage protein.
D)transport protein.
E)hormone.

Question 18

Which functional group is least important in biochemistry?

A)amide
B)amine
C)aromatic
D)ester
E)hydroxyl

Question 19

Which amino acid is classified as neutral and non-polar?

A)aspartic acid
B)histidine
C)phenylalanine
D)lysine
E)tyrosine

Question 20

Which molecule is an alpha amino acid?

A)

B)

C)

D)

E)

Question 21

Which molecule is chiral?

A)CH₃OH
B)CH₃CH₂OH
C)CH₂Cl₂
D)CHCl₂Br
E)CHFClBr

Question 22

Amino acids found in proteins all have the following features:

A)All are α-amino acids.
B)All are L-amino acids.
C)All are D- amino acids.
D)All are correct.
E)None are correct.

Question 23

An amino acid will have the form shown at

A)a pH of 7.0.
B)any pH other than 7.0.
C)a pH greater than its isoelectric point.
D)its isoelectric point.
E)a pH less than its isoelectric point.

Question 24

The N-terminal amino acid in the peptide Ala-Leu-Gly-His-Pro is

A)Alanine.
B)Leucine.
C)Glycine.
D)Histidine.
E)Proline.

Question 25

The pH at which the positive and negative charges of an amino acid balance each other is called the

A)isoelectric point.
B)isobaric point.
C)isobestic point.
D)isotonic point.
E)isomer point.

Question 26

The amino acid sequence of a protein is known as its

A)primary structure.
B)secondary structure.
C)tertiary structure.
D)quaternary structure.
E)none of the above

Question 27

Which amino acid is not chiral?

A)alanine
B)arginine
C)cysteine
D)glycine
E)phenylalanine

Question 28

Enantiomers are a form of stereoisomer in which each molecule in the pair of isomers has

A)its functional groups situated in different configurations with respect to a double bond.
B)the same carbon skeleton and the same functional groups,but the functional groups are attached at different sites.
C)the same functional groups,but a different carbon skeleton.
D)a carbon atom bonded to four different groups and the isomers are mirror images.
E)a plane of symmetry perpendicular to the carbon skeleton so that the bottom half and top half of the molecule are mirror images.

Question 29

Where in a protein structure are basic groups located?

A)at the N-terminal end
B)at the C-terminal end
C)on the Lys,Arg and His side chains
D)both A and C
E)none of the above

Question 30

Which structure represents a zwitterion?

A)

B)

C)

D)

E)

Question 31

Proteins are least soluble in water at

A)their isoelectric point.
B)low pH.
C)neutral pH.
D)high pH.
E)both high and low pH.

Question 32

The tripeptide represented as ala-leu-gly is named

A)Alanine-glycine-leucine.
B)Alanylglycylleucine.
C)Alanine-leucine-glycine.
D)Alanylleucylglycine.
E)none of these

Question 33

Which of the following objects is chiral?

A)a Ping-Pong ball
B)a nail
C)a shoe
D)a fork
E)a windowpane

Question 34

By convention,the N-terminal end of a protein is usually placed on the ________ of a protein structure.

A)right side
B)left side
C)center
D)bottom
E)top

Question 35

Which object is not chiral?

A)a dog
B)a clock
C)a boot
D)a truck
E)a thumbtack

Question 36

This question has four parts:
a.For the amino acid shown above in zwitterion form,circle the carboxyl group,underline the amine group,label the alpha carbon,and draw a box around the R group.
b.Write the name and abbreviation of your amino acid.
c.Classify the amino acid as polar,non-polar,acidic,or basic.Explain the basis for your classification.
d.Draw the structure of the amino acid at a pH well below its isoelectric point and well above its isoelectric point.

Question 37

List three properties of enantiomers that are the same and three properties that are different.

Question 38

An amino acid has the form shown at

A)a pH of 7.0.
B)any pH other than 7.0.
C)a pH greater than its isoelectric point.
D)its isoelectric point.
E)a pH less than its isoelectric point.

Question 39

Which of these amino acids has a thiol group as part of its side chain?

A)cysteine
B)tyrosine
C)histidine
D)threonine
E)methionine

Question 40

The isoelectric point of an amino acid is

A)the pH at which it exists in the basic form.
B)the pH at which it exists in the acid form.
C)the pH at which it exists in the zwitterion form.
D)the pH equal to its pK_a.
E)the pH equal to its pK_b.

Question 41

Which pair of amino acids can have ionic interactions?

A)arginine and glutamic acid
B)asparagine and lysine
C)leucine and alanine
D)glutamic acid and serine
E)glycine and asparagine

Question 42

All of the following are non-covalent interactions important in maintaining the secondary,tertiary,and quaternary aspects of amino acids except

A)sulfur-sulfur bonds.
B)hydrogen bonding along the backbone.
C)hydrogen bonding between R groups.
D)salt bridges between R groups.
E)hydrophobic interactions between R groups.

Question 43

How many different tripeptides can be formed from one molecule each of the amino acids tyrosine,valine,and alanine?

A)3
B)6
C)9
D)12
E)24

Question 44

Which pair of amino acids can form hydrogen bonds between their R groups?

A)arginine and glutamate
B)aspartate and lysine
C)leucine and alanine
D)glutamine and serine
E)glycine and asparagine

Question 45

The quaternary structure of hemoglobin contains

A)two subunits.
B)four subunits.
C)six subunits.
D)eight subunits.

Question 46

The type of bond that is most important in maintaining secondary structure of a protein is

A)disulfide bridges.
B)hydrogen bonding within the backbone.
C)hydrogen bonding between R groups.
D)salt bridges.
E)hydrophobic interactions.

Question 47

The two protein chains in insulin are held together by ________.

A)disulfide linkages
B)hydrophobic interactions
C)hydrogen bonds
D)salt bridges
E)All of the above

Question 48

In the tetrapeptide Ala-Cys-Val-Leu,the N-terminal amino acid is ________.

A)Ala
B)Cys
C)Val
D)Leu
E)none of the above

Question 49

Which amino acid can form covalent sulfur-sulfur bonds?

A)cysteine
B)glycine
C)proline
D)methionine
E)phenylalanine

Question 50

All of the following are globular proteins except

A)myosin.
B)ribonuclease.
C)hemoglobin.
D)albumin.
E)immunoglobulin.

Question 51

Which protein is considered to be a globular protein?

A)albumin
B)keratin
C)collagen
D)myosin

Question 52

The C-terminal amino acid in the peptide Ala-Leu-Gly-His-Pro is

A)Alanine.
B)Leucine.
C)Glycine.
D)Histidine.
E)Proline.

Question 53

Which type of interaction is not directly involved in maintaining tertiary structure?

A)disulfide bridges
B)hydrogen bonding
C)peptide bonds
D)salt bridges
E)hydrophobic interactions

Question 54

All of the following are examples of fibrous proteins except

A)wool.
B)fingernails.
C)skin.
D)insulin.
E)bones.

Question 55

All of the following are conjugated proteins except

A)cytochrome oxidase.
B)low-density lipoproteins.
C)myoglobin.
D)collagen.
E)casein.

Question 56

Proteins that consist of two or more chains assembled into a large 3-dimensional structure are said to display

A)primary structure.
B)secondary structure.
C)tertiary structure.
D)quaternary structure.
E)none of the above

Question 57

Keratin,the protein of hair and skin,has extensive sections with which secondary structure?

A)beta-pleated sheet
B)alpha-helix
C)random coil
D)alpha-beta

Question 58

Which pair of amino acids can have hydrophobic interactions?

A)arginine and glutamic acid
B)aspartic acid and lysine
C)leucine and alanine
D)glutamic acid and serine
E)glycine and asparagine

Question 59

In the tetrapeptide Ala-Cys-Val-Leu,the C-terminal amino acid is ________.

A)Ala
B)Cys
C)Val
D)Leu
E)none of the above

Question 60

The beta-pleated sheet is an example of

A)primary structure.
B)secondary structure.
C)tertiary structure.
D)quaternary structure.
E)none of the above

Question 61

Match the following.
hydrophilic

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 62

List three denaturing agents that can act on proteins and explain how each one disrupts the protein's structure.

Question 63

Match the following.
simple protein

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 64

Match the following.
globular protein

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 65

Protein denaturation results in a disruption of the

A)primary structure.
B)secondary and tertiary structure.
C)primary and secondary structure.
D)quaternary structure

Question 66

Which of the following processes involve protein denaturation?

A)permanent waving of hair
B)whipping cream
C)cooking egg whites
D)More than one response is correct.

Question 67

Match the following.
fibrous protein

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 68

Match the following.
conjugated protein

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 69

All of the following can denature proteins without hydrolysis except

A)heat.
B)mechanical stress.
C)enzyme treatment.
D)lowering of pH.
E)heavy metal ions.

Question 70

Match the following.
hydrophobic

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 71

Match the following.
zwitterion

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 72

Match the following.
native protein

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis

Question 73

When a protein is ________,its primary structure is destroyed,thus destroying the other aspects of its structure.

A)denatured
B)hydrolyzed
C)ionized
D)polymerized
E)esterified

Question 74

When a glycoprotein is hydrolyzed,the products would include

A)amino acids only.
B)amino acids plus metal ions.
C)amino acids plus carbohydrates.
D)amino acids plus lipids.
E)amino acids plus RNA.

Question 75

Detergents would most likely disrupt what type of stabilizing interaction?

A)salt bridges
B)hydrogen bonds
C)disulfide bonds
D)hydrophobic interactions
E)hydrophilic interactions

Question 76

All of the following are examples of denaturing proteins except

A)souring of milk.
B)a mild sunburn.
C)using a curling iron on your hair.
D)pounding meat to tenderize it.
E)digestion of a meal.

Question 77

When a protein is ________,its primary structure is maintained,but other aspects of its structure are disrupted.

A)denatured
B)hydrolyzed
C)ionized
D)polymerized
E)esterified

Question 78

Match the following.
chiral carbon

A)a protein that produces only amino acids upon hydrolysis
B)the form of an amino acid in which both the carboxyl group and the amine group are charged,but the overall molecule remains neutral
C)a protein that is usually insoluble in water,is very tough,and has a long shape
D)a carbon atom bonded to four different groups and therefore able to form enantiomers
E)a protein with the tertiary structure in which it normally occurs in living systems
F)refers to R groups that do not interact readily with water because they are non-polar
G)a protein that is usually water soluble,having a hydrophilic exterior and hydrophobic interior,and an overall rounded shape
H)refers to R groups which form hydrogen bonds with water because of their polarity
I)a protein that produces amino acids and other biomolecules or inorganic substances upon hydrolysis