Deck 20: Proteins

Question 1

In a solution that is highly acidic (low pH), which of the following forms of the amino acid alanine (Ala) would predominate?

A)
B)
C)
D)

Answer 1

Question 2

The joining together of two amino acids to form a dipeptide involves the reaction between

A) two amide groups
B) an amino group and an alpha-carbon
C) an amino group and a carboxyl group
D) an alpha-carbon and a hydroxyl group

Answer 2

an amino group and a carboxyl group

Question 3

Quaternary structure is possible for a protein only when:

A) The amino acid cysteine is present.
B) All amino acids have nonpolar R groups.
C) Two or more protein chains are present.
D) A protein chain bends back on itself.

Answer 3

Two or more protein chains are present.

Question 4

Which of the following amino acids would be classified as a polar neutral amino acid?

A)
B)
C)
D)

Question 5

How do the standard amino acids differ from one another?

A) in whether or not the amino group is chiral
B) in whether or not the carboxyl group is chiral
C) in the number of chiral carbon atoms between the carboxyl group and the amino group
D) in the identity of the R group (side chain)

Question 6

Which of the following sets of elements is a possible composition for a standard amino acid?

A) carbon, hydrogen, oxygen, and sulfur
B) carbon, hydrogen, nitrogen, and sulfur
C) carbon, hydrogen, and nitrogen
D) carbon, hydrogen, oxygen, nitrogen, and sulfur

Question 7

Which of the following forms of the amino acid alanine (Ala) is the zwitterion form of this amino acid?

A)
B)
C)
D)

Question 8

In the tetrapeptide Phe-Gln-Trp-His, the C-terminal amino acid is

A) Phe
B) Gln
C) Trp
D) His

Question 9

How many peptide linkages are present in a tripeptide?

A) two
B) three
C) four
D) five

Question 10

Which of the following statements concerning proteins is incorrect?

A) ansvara
B) All proteins contain the elements C, H, O, and N.
C) ansvarc
D) ansvard

Question 11

Which of the following biochemically important small peptides functions as an antioxidant?

A) oxytocin
B) vasopressin
C) Met-enkephalin
D) glutathione

Question 12

The complete hydrolysis of a protein produces a mixture of

A) polypeptides
B) free amino acids
C) polypeptides and free amino acids
D) dipeptides and free amino acids

Question 13

To which of the following levels of protein structure is the sequence of amino acids in a protein directly related?

A) primary
B) secondary
C) tertiary
D) quaternary

Question 14

Proteins are polymers in which:

A) Unbranched chains of amino acids are present.
B) Branched chains of amino acids are present.
C) Both unbranched and branched chains of amino acids are present.
D) Alternating amino acid and glucose monomer units are present.

Question 15

Interactions between amino acid R groups is responsible for which of the following levels of protein structure?

A) primary
B) secondary
C) tertiary
D) both secondary and tertiary

Question 16

Which of the following is an incorrect characterization for the protein hemoglobin?

A) multimeric protein
B) globular protein
C) simple protein
D) conjugated protein

Question 17

The non-amino acid portion of a conjugated protein is called a

A) side chain
B) prosthetic group
C) hydrophobic group
D) hydrophilic group

Question 18

Which of the following statements concerning standard amino acids is incorrect?

A) There are four main categories of amino acids.
B) They are all alpha-amino acids.
C) None of the standard amino acids are chiral.
D) ansvard

Question 19

How many different tripeptides can be formed from two molecules of leucine (Leu) and one molecule of glutamic acid (Glu)?

A) two
B) three
C) four
D) five

Question 20

Which of the following would be a correct representation of a portion of a protein "backbone"?

A)
B)
C)
D)

Question 21

Glycine, the simplest amino acid, is different from all of the other standard amino acids in that it

A) does not have a chiral center
B) has a side chain that does not contain carbon
C) occurs naturally as a D-isomer rather than as a L-isomer
D) more than one correct response
E) no correct response

Question 22

In a solution of high pH, all of the acidic and basic sites in an amino acid are

A) protonated
B) deprotonated
C) negatively charged
D) more than one correct response
E) no correct response

Question 23

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) Partial hydrolysis of the tripeptide Ala-Gly-Cys produces three different dipeptides.
(2) The number of standard amino acids is 23.
(3) Enkephalins are peptides that bind at receptor sites in the brain to reduce pain.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 24

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) The major force responsible for protein secondary structure is hydrogen bonding.
(2) Amino acids found in proteins are almost always L-isomers.
(3) Conjugated proteins always contain one or more prosthetic groups.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 25

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements: (1) Some tertiary-structure interactions involve covalent bonding.
(2) Nonpolar amino acids contain one amino group, one carboxyl group, and a nonpolar side chain.
(3) The two amino acids present in a dipeptide are linked via an amide linkage.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 26

R-group interaction between which of the following pairs of amino acids produces a disulfide bond?

A) cysteine-cysteine
B) proline-proline
C) alanine-glycine
D) more than one correct response
E) no correct response

Question 27

In which of the following pairs of proteins are both members of the pair fibrous proteins?

A) alpha-keratin and collagen
B) collagen and hemoglobin
C) hemoglobin and myoglobin
D) more than one correct response
E) no correct response

Question 28

Parallel polypeptide chains in a beta-pleated sheet conformation are held together by

A) R-group interactions
B) covalent bonding
C) hydrogen bonding
D) more than one correct response
E) no correct response

Question 29

Which of the following elements is present in some of the standard amino acids but not all of them?

A) oxygen
B) sulfur
C) phosphorus
D) more than one correct response
E) no correct response

Question 30

Which of the following statements concerning the tripeptide Val-Ala-Gly is correct?

A) The C-terminal amino acid residue is Val.
B) The N-terminal amino acid residue is Gly.
C) Three peptide linkages are present.
D) More than one correct response.
E) No correct response.

Question 31

Which of the following terms describes a protein secondary structure?

A) alpha helix
B) globular shape
C) fibrous shape
D) more than one correct response
E) no correct response

Question 32

Which of the following statements concerning proteins is correct?

A) Some, but not all, multimeric proteins are also conjugated proteins.
B) All monomeric proteins are also simple proteins.
C) Some, but not all, globular proteins are also multimeric proteins.
D) More than one correct response.
E) No correct response.

Question 33

Which of the following types of interactions contribute to protein tertiary structure?

A) hydrophobic interactions between nonpolar R groups
B) hydrogen bonds between polar neutral R groups
C) hydrogen bonds between C=O and N-H groups
D) more than one correct response
E) no correct response

Question 34

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements: (1) In pure form, amino acids are white crystalline solids with limited solubility in water.
(2) In an alpha-helix structure, all of the amino acid side chains lie outside the helix.
(3) Protein denaturation affects all four levels of protein structure.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 35

Which of the following tripeptides is a possible product from the partial hydrolysis of Ala-Val-Gly-Gly-Ala-Val?

A) Gly-Gly-Ala
B) Ala-Val-Ala
C) Ala-Val-Val
D) more than one correct response
E) no correct response

Question 36

Which of the following types of standard amino acids exist as zwitterions in the solid state?

A) polar neutral amino acids
B) polar acidic amino acids
C) nonpolar amino acids
D) more than one correct response
E) no correct response

Question 37

A total of six isomeric tetrapeptides can be made from which of the following combinations of amino acids?

A) Ala, Ala, Val, and Val
B) Val, Val, Val, and Ala
C) Ala, Ala, Val, and Gly
D) more than one correct response
E) no correct response

Question 38

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) In a peptide, the number of amino acids and the number of peptide bonds are always equal.
(2) HDL and LDL are examples of lipoproteins.
(3) Tertiary structure interactions in proteins always involve amino acid R groups.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 39

Which of the following levels of protein structure is not disrupted when protein hydrolysis occurs?

A) primary structure
B) secondary structure
C) tertiary structure
D) more than one correct response
E) no correct response

Question 40

Which of the following statements concerning protein structure is correct?

A) Amino acids are connected to each other through peptide bonds.
B) At least one unit of each of the 20 standard amino acids musts be present.
C) More than one chain of amino acids may be present.
D) More than one correct response.
E) No correct response.

Question 41

Use the following to answer the questions below:
Aspartic acid, an acidic amino acid, can have four different forms in solution. These four forms are given in the response list. For each of the conditions or characterizations, select from the response list the form of aspartic acid that will be dominant. Responses may be used more than once or need not be used at all.
Form in a solution of pH 13

A)

B)

C)

D)

Question 42

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) In the tripeptide Gly-Ala-Ser, the amino acid at the N-terminal end is Ser.
(2) More than one polypeptide chain may be present in a conjugated protein but not in a simple protein.
(3) In solution at physiological pH, the side chain of a polar basic amino acid bears a negative charge.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 43

Use the following to answer the questions below:
Use the response list to answer the following questions concerning the pentapeptide Gly-Ala-Gly-Gly-Ala. Responses may be used more than once or need not be used at all.

Number of possible different dipeptides produced by partial hydrolysis

A)zero
B)two
C)three
D)four

Question 44

Use the following to answer the questions below:
Determine the structural level (primary, secondary, etc.) associated with each of the protein characteristics using the response list. Responses may be used more than once or need not be used at all.
Hydrogen bonding between amide hydrogen atoms and carbonyl oxygen atoms

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

Question 45

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) Collagen, the most abundant protein in humans, is both a fibrous protein and a glycoprotein.
(2) Quaternary structure, the highest level of protein organization, is found in all proteins in which 80 or more amino acids are present.
(3) A protein chain lacks directionality because its two ends always involve the same amino acid.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 46

Use the following to answer the questions below:
Use the response list to answer the following questions concerning the pentapeptide Gly-Ala-Gly-Gly-Ala. Responses may be used more than once or need not be used at all.

Number of different amino acids produced by complete hydrolysis

A)zero
B)two
C)three
D)four

Question 47

Use the following to answer the questions below:
Determine the structural level (primary, secondary, etc.) associated with each of the protein characteristics using the response list. Responses may be used more than once or need not be used at all.
Sequence of amino acids in a protein chain

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

Question 48

Use the following to answer the questions below:
Determine the structural level (primary, secondary, etc.) associated with each of the protein characteristics using the response list. Responses may be used more than once or need not be used at all.
Three-dimensional shape resulting from R-group interactions

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

Question 49

Use the following to answer the questions below:
Aspartic acid, an acidic amino acid, can have four different forms in solution. These four forms are given in the response list. For each of the conditions or characterizations, select from the response list the form of aspartic acid that will be dominant. Responses may be used more than once or need not be used at all.
Form in a solution of pH 1

A)

B)

C)

D)

Question 50

Use the following to answer the questions below:
Use the response list to answer the following questions concerning the pentapeptide Gly-Ala-Gly-Gly-Ala. Responses may be used more than once or need not be used at all.

Number of peptide linkages present

A)zero
B)two
C)three
D)four

Question 51

Use the following to answer the questions below:
Aspartic acid, an acidic amino acid, can have four different forms in solution. These four forms are given in the response list. For each of the conditions or characterizations, select from the response list the form of aspartic acid that will be dominant. Responses may be used more than once or need not be used at all.
Form in which no net charge is present

A)

B)

C)

D)

Question 52

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) The antirejection drug cyclosporine is structurally a small cyclic peptide.
(2) The chemical basis for a hair permanent is reversible denaturation in which peptide linkages are broken and reformed.
(3) Immature human milk (colostrum) does not contain protein.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 53

Use the following to answer the questions below:
Determine the structural level (primary, secondary, etc.) associated with each of the protein characteristics using the response list. Responses may be used more than once or need not be used at all.
Beta pleated-sheet configuration

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

Question 54

Use the following to answer the questions below:
Use the response list to answer the following questions concerning the pentapeptide Gly-Ala-Gly-Gly-Ala. Responses may be used more than once or need not be used at all.

Number of possible different tripeptides produced by partial hydrolysis

A)zero
B)two
C)three
D)four

Question 55

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) For neutral amino acids, three different forms can exist, with the form found dependent of solution pH.
(2) Hydrophobic interactions are the strongest of the tertiary-structure interactions.
(3) Protein digestion is an enzyme-catalyzed hydrolysis reaction.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 56

Use the following to answer the questions below:
Determine the structural level (primary, secondary, etc.) associated with each of the protein characteristics using the response list. Responses may be used more than once or need not be used at all.
Alpha-helix configuration

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

Question 57

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
Statements:
(1) For a tripeptide in which the three amino acids are different, six isomeric forms are possible.
(2) The "backbone" of a protein is an alternating sequence of C and N atoms.
(3) Both alpha-helix and beta-pleated sheet configurations can be present in the same protein.

A) All three statements are true.
B) Two of the three statements are true.
C) Only one of the statements is true.
D) None of the statements is true.

Question 58

Use the following to answer the questions below:
Use the response list to answer the following questions concerning the pentapeptide Gly-Ala-Gly-Gly-Ala. Responses may be used more than once or need not be used at all.

Number of possible different tripeptides produced by denaturation

A)zero
B)two
C)three
D)four

Question 59

Use the following to answer the questions below:
Aspartic acid, an acidic amino acid, can have four different forms in solution. These four forms are given in the response list. For each of the conditions or characterizations, select from the response list the form of aspartic acid that will be dominant. Responses may be used more than once or need not be used at all.
Zwitterion form

A)

B)

C)

D)

Question 60

Use the following to answer the questions below:
Aspartic acid, an acidic amino acid, can have four different forms in solution. These four forms are given in the response list. For each of the conditions or characterizations, select from the response list the form of aspartic acid that will be dominant. Responses may be used more than once or need not be used at all.
Positively-charged form

A)

B)

C)

D)

Question 61

Use the following to answer the questions below:
Identify the standard amino acid with each of the characteristics using the response list. Responses may be used more than once or need not be used at all.

Only standard amino acid that participates in disulfide bonds

A) proline
B) cysteine
C) glycine
D) alanine

Question 62

Use the following to answer the questions below:
Identify the standard amino acid with each of the characteristics using the response list. Responses may be used more than once or need not be used at all.

Only standard amino acid with a methyl group attached to its alpha carbon atom

A) proline
B) cysteine
C) glycine
D) alanine

Question 63

Use the following to answer the questions below:
Identify the standard amino acid with each of the characteristics using the response list. Responses may be used more than once or need not be used at all.

Only standard amino acid whose side chain does not contain carbon

A) proline
B) cysteine
C) glycine
D) alanine

Question 64

Use the following to answer the questions below:
Identify the standard amino acid with each of the characteristics using the response list. Responses may be used more than once or need not be used at all.

Only standard amino acid that is achiral

A) proline
B) cysteine
C) glycine
D) alanine

Question 65

Use the following to answer the questions below:
Identify the standard amino acid with each of the characteristics using the response list. Responses may be used more than once or need not be used at all.

Only standard amino acid with a cyclic side chain

A) proline
B) cysteine
C) glycine
D) alanine