Question 1

Matching

-At a pH below its pKa,the $\varepsilon$-amino group of lysine 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 L

Question 2

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 E

Question 3

The two peptides shown in the diagram below are linked through

Accepted Answer

A) a hydrogen bond. 
B) a glycosidic bond. 
C) a peptide bond. 
D) a disulfide bond. 
E) an ester linkage. 
A) a hydrogen bond. 
B) a glycosidic bond. 
C) a peptide bond. 
D) a disulfide bond. 
E) an ester linkage. D

Question 4

The side-chains of amino acids have

Accepted Answer

A) a positive charge in every situation. 
B) pKas that assure the solubility of every protein. 
C) constant pKas no matter what aqueous environment they are found in. 
D) different pKas in peptides as compared to the free amino acids 
E) polar functional groups. 
A) a positive charge in every situation. 
B) pKas that assure the solubility of every protein. 
C) constant pKas no matter what aqueous environment they are found in. 
D) different pKas in peptides as compared to the free amino acids 
E) polar functional groups.

Question 5

The tripeptide glycylarginylglutamate contains four ionizable groups with pKas of 2.1,4.1 9.8,and 12.5.Calculate the pI for this molecule.

Accepted Answer

A) 3)1 
B) 6)4 
C) 7)0 
D) 7)3 
E) 8)3 
A) 3)1 
B) 6)4 
C) 7)0 
D) 7)3 
E) 8)3

Question 6

The pK1,pK2,and pKR for the amino acid glutamate are 2.1,9.5,and 4.1,respectively.At pH 11.0,glutamate would be charged predominantly as follows:

Accepted Answer

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

Question 7

The pK1,pK2,and pKR for the amino acid lysine are 2.2,9.1,and 10.5,respectively.At pH 1.0,lysine would be charged predominantly as follows:

Accepted Answer

A) "$\alpha$-carboxylate 0,$\alpha$-amino −1$\varepsilon$-amino −1,net charge −2" 
B) "$\alpha$-carboxylate −1,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +1" 
C) "$\alpha$-carboxylate +1,$\alpha$-amino +2,$\varepsilon$-amino +2,net charge +5" 
D) "$\alpha$-carboxylate 0,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +2" 
E) "$\alpha$-carboxylate +2,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +4" 
A) "$\alpha$-carboxylate 0,$\alpha$-amino −1$\varepsilon$-amino −1,net charge −2" 
B) "$\alpha$-carboxylate −1,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +1" 
C) "$\alpha$-carboxylate +1,$\alpha$-amino +2,$\varepsilon$-amino +2,net charge +5" 
D) "$\alpha$-carboxylate 0,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +2" 
E) "$\alpha$-carboxylate +2,$\alpha$-amino +1,$\varepsilon$-amino +1,net charge +4"

Question 8

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 9

In general,amino acids are chiral molecules that act as building blocks for proteins.In addition,amino acids and amino acid derivative can act as extracellular messenger molecules such as hormones or neurotransmitters.
a.How many different amino acids can be incorporated into proteins during translation?
b.Do ribosomes use L or D amino acids for protein synthesis?
c.Name one amino acid or amino acid derivative that can act as hormone or neurotransmitter.
d.Draw the predominant structure of valine at pH 10 (pKas are 2.3 and 9.7).

Accepted Answer

a.20
b.L
c.glycine,g

Question 10

Matching

-In the tripeptide Lys─Pro─Ile,there are ______ charged groups at pH 7.

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

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 12

Questions are based on the diagram below.  
-Residues 1 and 2 in the peptide shown above are connected through a

Accepted Answer

A) hydrogen bond. 
B) an isopeptide bond. 
C) an ester linkage. 
D) disulfide bond. 
E) a glycosidic bond. 
A) hydrogen bond. 
B) an isopeptide bond. 
C) an ester linkage. 
D) disulfide bond. 
E) a glycosidic bond.

Question 13

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 14

While proteins are usually composed of linear chains of amino acids,branched chains of amino acids and internally cross-linked chains can be found in certain proteins.Polypeptide chains are most commonly linked to each other through

Accepted Answer

A) hydrogen bonds. 
B) glycosidic bonds. 
C) peptide bonds. 
D) disulfide bonds. 
E) ester linkages. 
A) hydrogen bonds. 
B) glycosidic bonds. 
C) peptide bonds. 
D) disulfide bonds. 
E) ester linkages.

Question 15

What percentage of the 20 amino acids is considered to be nutritionally essential to lab animals?

Accepted Answer

A) 0% 
B) 25% 
C) 50% 
D) 75% 
E) 100% 
A) 0% 
B) 25% 
C) 50% 
D) 75% 
E) 100%

Question 16

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 17

The figure below shows the predominant structure of an oligopeptide at pH 7.0.   
a.How many amino acids are present in this peptide?
b.Circle one peptide bond in this peptide.
c.Draw a square around one alpha carbon in this peptide
d.The pKas of the ionizable groups in this peptide are 2.0,4.0,and 9.0.What is the ionic charge of this molecule at pH 1.0
e.What is the name of the N-terminal amino acid in this peptide?

Accepted Answer

a.5
b. @#IMG-DLM& 
c.
d.The charge of this molecul

Question 18

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 19

Zwitterions are

Accepted Answer

A) amino acids. 
B) ionic molecules that are racemic. 
C) ions that bear both negatively and positively charged groups. 
D) side chain carboxylate anions. 
E) delocalized ions. 
A) amino acids. 
B) ionic molecules that are racemic. 
C) ions that bear both negatively and positively charged groups. 
D) side chain carboxylate anions. 
E) delocalized ions.

Question 20

Which of the following tripeptides carries a net positive charge at pH 7.0?

Accepted Answer

A) Ala─Thr─Asn 
B) Gln─Val─Ser 
C) Arg─Glu─Met 
D) Pro─Ile─Leu 
E) Leu─Lys─Gly 
A) Ala─Thr─Asn 
B) Gln─Val─Ser 
C) Arg─Glu─Met 
D) Pro─Ile─Leu 
E) Leu─Lys─Gly

Exam 4: Amino Acids

Matching -At a pH below its pKa,the ε\varepsilonε -amino group of lysine is ______.

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

The two peptides shown in the diagram below are linked through

The side-chains of amino acids have

The tripeptide glycylarginylglutamate contains four ionizable groups with pKas of 2.1,4.1 9.8,and 12.5.Calculate the pI for this molecule.

The pK1,pK2,and pKR for the amino acid glutamate are 2.1,9.5,and 4.1,respectively.At pH 11.0,glutamate would be charged predominantly as follows:

The pK1,pK2,and pKR for the amino acid lysine are 2.2,9.1,and 10.5,respectively.At pH 1.0,lysine would be charged predominantly as follows:

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.

Matching -In the tripeptide Lys─Pro─Ile,there are ______ charged groups at pH 7.

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

Questions are based on the diagram below. -Residues 1 and 2 in the peptide shown above are connected through a

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

While proteins are usually composed of linear chains of amino acids,branched chains of amino acids and internally cross-linked chains can be found in certain proteins.Polypeptide chains are most commonly linked to each other through

What percentage of the 20 amino acids is considered to be nutritionally essential to lab animals?

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

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

Zwitterions are

Which of the following tripeptides carries a net positive charge at pH 7.0?

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

Matching -At a pH below its pK_a,the $\varepsilon$ -amino group of lysine is ______.

The tripeptide glycylarginylglutamate contains four ionizable groups with pK_as of 2.1,4.1 9.8,and 12.5.Calculate the pI for this molecule.

The pK₁,pK₂,and pK_R for the amino acid glutamate are 2.1,9.5,and 4.1,respectively.At pH 11.0,glutamate would be charged predominantly as follows:

The pK₁,pK₂,and pK_R for the amino acid lysine are 2.2,9.1,and 10.5,respectively.At pH 1.0,lysine would be charged predominantly as follows:

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.

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