Question 1

Matching
-In the tripeptide Lys─Pro─Ile, the C-terminal residue 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 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

Matching
-In the peptide Trp─Ser─Val, valine is at the ______.

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 4

An amide bond between a side-chain carboxylate and an $\alpha$-amino group is also called a(n)

Accepted Answer

A) disulfide bond. 
B) anhydride bond. 
C) ester bond. 
D) isopeptide bond. 
E) glycosidic bond. 
A) disulfide bond. 
B) anhydride bond. 
C) ester bond. 
D) isopeptide bond. 
E) glycosidic bond.

Question 5

Matching
-Glutathione is a tripeptide containing a central ______ residue.

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 6

Glutamine is an amino acid (pKas are 2.2, and 9.1).Draw the predominant structure of glutamine at pH 1.0.

Accepted Answer

Question 7

Glutamic acid is an amino acid (pKas are 2.1, 4.1 and 9.5).Calculate the isoelectric point of glutamic acid.

Accepted Answer

At pH 1.0 glutamic acid has an electric

Question 8

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 9

Typically, modified amino acids, those with side chain modifications that are present in proteins

Accepted Answer

A) are synthesized due to genetic mutations. 
B) are assembled by specialized bacterial enzymes. 
C) are formed by modification of standard side chain residues after the protein is synthesized. 
D) are toxic. 
E) are racemic. 
A) are synthesized due to genetic mutations. 
B) are assembled by specialized bacterial enzymes. 
C) are formed by modification of standard side chain residues after the protein is synthesized. 
D) are toxic. 
E) are racemic.

Question 10

Ribosomes use L amino acids to synthesize proteins.These amino acids are called "L" because

Accepted Answer

A) they are chiral. 
B) they turn polarized light to the left. 
C) they have a configuration of groups around the C$\alpha$ that can be related to the configuration of groups around the asymmetric carbon in L-glyceraldehyde. 
D) they are all (S)-amino acids. 
E) they are all (R)-amino acids. 
A) they are chiral. 
B) they turn polarized light to the left. 
C) they have a configuration of groups around the C$\alpha$ that can be related to the configuration of groups around the asymmetric carbon in L-glyceraldehyde. 
D) they are all (S)-amino acids. 
E) they are all (R)-amino acids.

Question 11

Which of the following amino acids has a charged polar side chain at pH 7.0?

Accepted Answer

A) Leu 
B) Ala 
C) Met 
D) Trp 
E) Glu 
A) Leu 
B) Ala 
C) Met 
D) Trp 
E) Glu

Question 12

Which of the following amino acids is the least abundant in proteins?

Accepted Answer

A) V 
B) W 
C) G 
D) F 
E) A 
A) V 
B) W 
C) G 
D) F 
E) A

Question 13

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 14

Which of the following amino acids does not have an ionizable side chain?

Accepted Answer

A) Asp 
B) Cys 
C) Lys 
D) His 
E) Asn 
A) Asp 
B) Cys 
C) Lys 
D) His 
E) Asn

Question 15

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 16

The tripeptide alanyllysylaspartate contains four ionizable groups with pKas of 2.0, 3.9, 9.9, and 10.5.Calculate the pI for this molecule.

Accepted Answer

A) 3.0 
B) 6.0 
C) 6.2 
D) 10.2 
E) none of the above 
A) 3.0 
B) 6.0 
C) 6.2 
D) 10.2 
E) none of the above

Question 17

Asx refers to

Accepted Answer

A) a negatively charged aspartic acid. 
B) a positively charged asparagine. 
C) a dipeptide containing both aspartic acid and asparagine. 
D) either aspartic acid or asparagine. 
E) an unnatural amino acid formed during acid hydrolysis of peptide bonds. 
A) a negatively charged aspartic acid. 
B) a positively charged asparagine. 
C) a dipeptide containing both aspartic acid and asparagine. 
D) either aspartic acid or asparagine. 
E) an unnatural amino acid formed during acid hydrolysis of peptide bonds.

Question 18

the diagram below  
-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 19

Ribosomes use L amino acids to synthesize proteins.These amino acids are called "L" because

Accepted Answer

A) they are chiral. 
B) they turn polarized light to the left. 
C) they are all (S)-amino acids. 
D) they are all (R)-amino acids. 
E) none of the above 
A) they are chiral. 
B) they turn polarized light to the left. 
C) they are all (S)-amino acids. 
D) they are all (R)-amino acids. 
E) none of the above

Question 20

The pK1, pK2, and pKR for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively.At pH 7.0, aspartic acid would be charged predominantly as follows:

Accepted Answer

A) ($\alpha$-carboxylate 0, $\alpha$-amino +1, $\beta$-carboxylate 0, net charge +1) 
B) ($\alpha$-carboxylate −1, $\alpha$-amino +1, $\beta$-carboxylate −1, net charge −1) 
C) ($\alpha$-carboxylate 0, $\alpha$-amino −1, $\beta$-carboxylate 0, net charge −1) 
D) ($\alpha$-carboxylate +1, $\alpha$-amino −1, $\beta$-carboxylate +1, net charge +1) 
E) ($\alpha$-carboxylate +1, $\alpha$-amino +1, $\beta$-carboxylate +1, net charge +3) 
A) ($\alpha$-carboxylate 0, $\alpha$-amino +1, $\beta$-carboxylate 0, net charge +1) 
B) ($\alpha$-carboxylate −1, $\alpha$-amino +1, $\beta$-carboxylate −1, net charge −1) 
C) ($\alpha$-carboxylate 0, $\alpha$-amino −1, $\beta$-carboxylate 0, net charge −1) 
D) ($\alpha$-carboxylate +1, $\alpha$-amino −1, $\beta$-carboxylate +1, net charge +1) 
E) ($\alpha$-carboxylate +1, $\alpha$-amino +1, $\beta$-carboxylate +1, net charge +3)

Exam 4: Amino Acids

Matching -In the tripeptide Lys─Pro─Ile, the C-terminal residue is _________.

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:

Matching -In the peptide Trp─Ser─Val, valine is at the ______.

An amide bond between a side-chain carboxylate and an α\alphaα -amino group is also called a(n)

Matching -Glutathione is a tripeptide containing a central ______ residue.

Glutamine is an amino acid (pKas are 2.2, and 9.1).Draw the predominant structure of glutamine at pH 1.0.

Glutamic acid is an amino acid (pKas are 2.1, 4.1 and 9.5).Calculate the isoelectric point of glutamic acid.

The diagram below shows

Typically, modified amino acids, those with side chain modifications that are present in proteins

Ribosomes use L amino acids to synthesize proteins.These amino acids are called "L" because

Which of the following amino acids has a charged polar side chain at pH 7.0?

Which of the following amino acids is the least abundant in proteins?

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

Which of the following amino acids does not have an ionizable side chain?

The disulfide bond between two cysteine molecules

The tripeptide alanyllysylaspartate contains four ionizable groups with pKas of 2.0, 3.9, 9.9, and 10.5.Calculate the pI for this molecule.

Asx refers to

the diagram below -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?

Ribosomes use L amino acids to synthesize proteins.These amino acids are called "L" because

The pK1, pK2, and pKR for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively.At pH 7.0, aspartic acid would be charged predominantly as follows:

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

Glycogen Metabolism and Gluconeogenesis

Glucose Catabolism

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

Translation

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:

An amide bond between a side-chain carboxylate and an $\alpha$ -amino group is also called a(n)

Glutamine is an amino acid (pK_as are 2.2, and 9.1).Draw the predominant structure of glutamine at pH 1.0.

Glutamic acid is an amino acid (pK_as are 2.1, 4.1 and 9.5).Calculate the isoelectric point of glutamic acid.

The tripeptide alanyllysylaspartate contains four ionizable groups with pK_as of 2.0, 3.9, 9.9, and 10.5.Calculate the pI for this molecule.

the diagram below -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?

The pK₁, pK₂, and pK_R for the amino acid aspartic acid are 2.0, 9.9, and 3.9, respectively.At pH 7.0, aspartic acid would be charged predominantly as follows: