Question 1

The __________ character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.

Accepted Answer

A) chiral 
B) zwitterionic 
C) polar 
D) hydrophobic 
E) none of the above 
A) chiral 
B) zwitterionic 
C) polar 
D) hydrophobic 
E) none of the above

Question 2

The pK1,pK2,and pKR for the amino acid histidine are 1.8,9.3,and 6.0,respectively.At pH 4.0 would be charged predominantly as follows:

Accepted Answer

A) "$\alpha$-carboxylate +1,$\alpha$-amino 0,imidazole −1,net charge 0" 
B) "$\alpha$-carboxylate −1,$\alpha$-amino +1,imidazole 0,net charge 0" 
C) "$\alpha$-carboxylate +1,$\alpha$-amino +1,imidazole −1,net charge +1" 
D) "$\alpha$-carboxylate −1,$\alpha$-amino +1,imidazole +1,net charge +1" 
E) "$\alpha$-carboxylate 0,$\alpha$-amino +1,imidazole +1,net charge +2" 
A) "$\alpha$-carboxylate +1,$\alpha$-amino 0,imidazole −1,net charge 0" 
B) "$\alpha$-carboxylate −1,$\alpha$-amino +1,imidazole 0,net charge 0" 
C) "$\alpha$-carboxylate +1,$\alpha$-amino +1,imidazole −1,net charge +1" 
D) "$\alpha$-carboxylate −1,$\alpha$-amino +1,imidazole +1,net charge +1" 
E) "$\alpha$-carboxylate 0,$\alpha$-amino +1,imidazole +1,net charge +2"

Question 3

Which one of the representations describes the oligopeptide shown below?

Accepted Answer

A) Tyr-Ala-Thr 
B) Tyr-Gly-Cys 
C) Tyr-Ala-Ser 
D) Phe-Gly-Cys 
E) Phe-Ala-Thr 
A) Tyr-Ala-Thr 
B) Tyr-Gly-Cys 
C) Tyr-Ala-Ser 
D) Phe-Gly-Cys 
E) Phe-Ala-Thr

Question 4

Which of the following amino acids has an uncharged polar side chain at pH 7.0?

Accepted Answer

A) Arg 
B) Thr 
C) Glu 
D) Pro 
E) Ile 
A) Arg 
B) Thr 
C) Glu 
D) Pro 
E) Ile

Question 5

Which of the following statements is true?

Accepted Answer

A) Amino acids can be derived from purines. 
B) Purines and pyrimidines can be derived from amino acids. 
C) Corn contains all 20 standard amino acids. 
D) Amino acids can be derived from pyrimidines. 
E) none of the above 
A) Amino acids can be derived from purines. 
B) Purines and pyrimidines can be derived from amino acids. 
C) Corn contains all 20 standard amino acids. 
D) Amino acids can be derived from pyrimidines. 
E) none of the above

Question 6

Tryptophan is an amino acid (pKas are 2.5,and 9.4).
a.How many different amino acids can be incorporated into proteins during translation?
b.Give the three- and one-letter abbreviation for tryptophan.
c.Draw the predominant structure of tryptophan at pH 7.0.
d.Calculate the pI of Tryptophan.

Accepted Answer

a.20
b.Trp

Question 7

The picture below shows the structure of serotonin.   
a.From which amino acid is serotonin derived?
b.What are the structural differences between serotonin and this amino acid?
c.What is the function of serotonin?
d.Which illness can be caused by reduced levels of serotonin in the brain?

Accepted Answer

a.Tryptophan
b.Serotonin has a

Question 8

In the early 1930's William Rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins.He observed that his rats lost weight.This observation led to the discovery of ______ as the 20th amino acid found in proteins.

Accepted Answer

A) Gly 
B) Ala 
C) Tyr 
D) Asn 
E) Thr 
A) Gly 
B) Ala 
C) Tyr 
D) Asn 
E) Thr

Question 9

Matching

-At a pH above its pKa,the phenol group of tyrosine is ______.

Accepted Answer

A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus 
A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus

Question 10

Matching

-The net charge of the zwitterion form of Gly is ______.

Accepted Answer

A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus 
A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus

Question 11

All amino acids derived from proteins have the same stereochemical conformation as.

Accepted Answer

A) L-glyceraldehyde. 
B) (R)-alanine. 
C) D-glucose. 
D) (S)-cysteine. 
E) glycine. 
A) L-glyceraldehyde. 
B) (R)-alanine. 
C) D-glucose. 
D) (S)-cysteine. 
E) glycine.

Question 12

The diagram below shows

Accepted Answer

A) an amino acid. 
B) a dipeptide. 
C) a tripeptide. 
D) a tetrapeptide. 
E) a polypeptide. 
A) an amino acid. 
B) a dipeptide. 
C) a tripeptide. 
D) a tetrapeptide. 
E) a polypeptide.

Question 13

Matching

-When a peptide bond is formed,an ______ reacts with a carboxylate group.

Accepted Answer

A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus 
A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus

Question 14

Which of the following tripeptides would be expected to be the most hydrophobic?

Accepted Answer

A) KYG 
B) KYA 
C) GYA 
D) DYA 
E) DYG 
A) KYG 
B) KYA 
C) GYA 
D) DYA 
E) DYG

Question 15

Questions are based on the diagram shown below.  
-What is the three-letter symbol for the C-terminal amino acid in the peptide shown above?

Accepted Answer

A) Gly 
B) Asp 
C) Tyr 
D) Met 
E) Phe 
A) Gly 
B) Asp 
C) Tyr 
D) Met 
E) Phe

Question 16

Questions are based on the diagram shown below.  
-How many amino acid residues are present in the peptide shown above?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) 5 
A) 1 
B) 2 
C) 3 
D) 4 
E) 5

Question 17

The ionization of amino acids depends on the pH and the pKas of the ionizable groups.The pK1 and pK2 for the amino acid shown above are 2.1 and 8.8,respectively.At what pH is the amino acid ionized predominantly as shown?

Accepted Answer

A) pH 1.0 
B) pH 2.1 
C) pH 5.5 
D) pH 8.8 
E) pH 10.0 
A) pH 1.0 
B) pH 2.1 
C) pH 5.5 
D) pH 8.8 
E) pH 10.0

Question 18

The formation of a dipeptide from two amino acids involves

Accepted Answer

A) side-chain complementarity. 
B) loss of water. 
C) oxidation of the $\alpha$-carbon. 
D) reduction of the $\alpha$-carbon. 
E) base catalysis. 
A) side-chain complementarity. 
B) loss of water. 
C) oxidation of the $\alpha$-carbon. 
D) reduction of the $\alpha$-carbon. 
E) base catalysis.

Question 19

The disulfide bond between two cysteine molecules

Accepted Answer

A) is a peptide bond. 
B) is an ionic interaction that is stable at physiological pH. 
C) is a covalent bond formed by oxidation. 
D) is a hydrogen bond between the two sulfhydryl groups. 
E) is a dipole-dipole interaction. 
A) is a peptide bond. 
B) is an ionic interaction that is stable at physiological pH. 
C) is a covalent bond formed by oxidation. 
D) is a hydrogen bond between the two sulfhydryl groups. 
E) is a dipole-dipole interaction.

Question 20

Matching

-At a pH below its pKa,the $\beta$-carboxylate group of Asp is ______.

Accepted Answer

A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus 
A)  glutamate 
B)  uncharged 
C)  deprotonated 
D)  three 
E)  amino group
F) two
G) C-terminus
H) lysine
I) racemic mixture
J) cysteine
K) zero
L) protonated
M) isoleucine
N) tryptophan
O) phenylalanine
P) N-terminus

Exam 4: Amino Acids

The __________ character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.

The pK1,pK2,and pKR for the amino acid histidine are 1.8,9.3,and 6.0,respectively.At pH 4.0 would be charged predominantly as follows:

Which one of the representations describes the oligopeptide shown below?

Which of the following amino acids has an uncharged polar side chain at pH 7.0?

Which of the following statements is true?

Tryptophan is an amino acid (pKas are 2.5,and 9.4). a.How many different amino acids can be incorporated into proteins during translation? b.Give the three- and one-letter abbreviation for tryptophan. c.Draw the predominant structure of tryptophan at pH 7.0. d.Calculate the pI of Tryptophan.

The picture below shows the structure of serotonin. a.From which amino acid is serotonin derived? b.What are the structural differences between serotonin and this amino acid? c.What is the function of serotonin? d.Which illness can be caused by reduced levels of serotonin in the brain?

In the early 1930's William Rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins.He observed that his rats lost weight.This observation led to the discovery of ______ as the 20th amino acid found in proteins.

Matching -At a pH above its pKa,the phenol group of tyrosine is ______.

Matching -The net charge of the zwitterion form of Gly is ______.

All amino acids derived from proteins have the same stereochemical conformation as.

The diagram below shows

Matching -When a peptide bond is formed,an ______ reacts with a carboxylate group.

Which of the following tripeptides would be expected to be the most hydrophobic?

Questions are based on the diagram shown below. -What is the three-letter symbol for the C-terminal amino acid in the peptide shown above?

Questions are based on the diagram shown below. -How many amino acid residues are present in the peptide shown above?

The ionization of amino acids depends on the pH and the pKas of the ionizable groups.The pK1 and pK2 for the amino acid shown above are 2.1 and 8.8,respectively.At what pH is the amino acid ionized predominantly as shown?

The formation of a dipeptide from two amino acids involves

The disulfide bond between two cysteine molecules

Matching -At a pH below its pKa,the β\betaβ -carboxylate group of Asp is ______.

Introduction to the Chemistry of Life

Water

Nucleotides, nucleic Acids, and Genetic Information

Proteins: Primary Structure

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Catalysis

Enzyme Kinetics, inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glucose Catabolism

Glycogen Metabolism and Gluconeogenesis

Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

DNA Replication, repair and Recombination

Transcription and Rna Processing

Protein Synthesis

Regulation of Gene Expression

Filters

The pK₁,pK₂,and pK_R for the amino acid histidine are 1.8,9.3,and 6.0,respectively.At pH 4.0 would be charged predominantly as follows:

Tryptophan is an amino acid (pK_as are 2.5,and 9.4). a.How many different amino acids can be incorporated into proteins during translation? b.Give the three- and one-letter abbreviation for tryptophan. c.Draw the predominant structure of tryptophan at pH 7.0. d.Calculate the pI of Tryptophan.

Matching -At a pH above its pK_a,the phenol group of tyrosine is ______.

The ionization of amino acids depends on the pH and the pK_as of the ionizable groups.The pK₁ and pK₂for the amino acid shown above are 2.1 and 8.8,respectively.At what pH is the amino acid ionized predominantly as shown?

Matching -At a pH below its pK_a,the $\beta$ -carboxylate group of Asp is ______.