Question 1

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"

Question 2

Matching

-GABA is a neurotransmitter derived from ______.

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 3

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 4

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 5

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 6

All the standard amino acids except ____ are optically active.

Accepted Answer

A) Pro 
B) Arg 
C) Trp 
D) Gly 
E) Phe 
A) Pro 
B) Arg 
C) Trp 
D) Gly 
E) Phe

Question 7

For the following questions  refer to the diagram below  
-What is the three-letter symbol for the amino acid shown above?

Accepted Answer

A) Ala 
B) Asn 
C) Gln 
D) Asp 
E) Glu 
A) Ala 
B) Asn 
C) Gln 
D) Asp 
E) Glu

Question 8

Which of the amino acids represented below has two chiral centers?

Accepted Answer

A) Ala 
B) Leu 
C) Ile 
D) Pro 
E) Asn 
A) Ala 
B) Leu 
C) Ile 
D) Pro 
E) Asn

Question 9

Questions are based on the diagram below.  
-What is the three-letter symbol of the N-terminal amino acid in the structure shown above?

Accepted Answer

A) Asp 
B) Asn 
C) Gln 
D) Glu 
E) Lys 
A) Asp 
B) Asn 
C) Gln 
D) Glu 
E) Lys

Question 10

Which of the five amino acids shown below has 2 chiral centers?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 11

Questions are based on the diagram below.  
-What is the name of this molecule?

Accepted Answer

A) "GABA" 
B) "thyroxine" 
C) "$\gamma$-carboxyglutamate" 
D) "glutathione" 
E) "epinephrine" 
A) "GABA" 
B) "thyroxine" 
C) "$\gamma$-carboxyglutamate" 
D) "glutathione" 
E) "epinephrine"

Question 12

The pK1,pK2,and pKR for the amino acid arginine are 1.8,9.0,and 12.5,respectively.At pH 7.0 arginine would be charged predominantly as follows:

Accepted Answer

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

Question 13

Matching

-Biological systems usually produce a single enantiomer,whereas chemical synthesis produces a ______.

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 isoelectronic point of an amino acid is the point where

Accepted Answer

A) the pKa of the $\alpha$-carboxylic acid is the same as the pKa of the $\alpha$-amino group. 
B) the $\alpha$-carboxylic acid is protonated and the $\alpha$-amino group is unprotonated. 
C) the solubility of the amino acid is maximized. 
D) the $\alpha$-carboxylic acid and the $\alpha$-amino group are both half protonated. 
E) the amino acid carries no net electrical charge. 
A) the pKa of the $\alpha$-carboxylic acid is the same as the pKa of the $\alpha$-amino group. 
B) the $\alpha$-carboxylic acid is protonated and the $\alpha$-amino group is unprotonated. 
C) the solubility of the amino acid is maximized. 
D) the $\alpha$-carboxylic acid and the $\alpha$-amino group are both half protonated. 
E) the amino acid carries no net electrical charge.

Question 16

Which of the following amino acids has a sulfur atom in its side chain?

Accepted Answer

A) Asn 
B) Ser 
C) Phe 
D) Met 
E) Tyr 
A) Asn 
B) Ser 
C) Phe 
D) Met 
E) Tyr

Question 17

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 18

The peptide AYDG has an N-terminal _________ residue.

Accepted Answer

A) glycine 
B) glutamic acid 
C) glutamine 
D) aspartic acid 
E) alanine 
A) glycine 
B) glutamic acid 
C) glutamine 
D) aspartic acid 
E) alanine

Question 19

The picture below shows the structure of $\gamma$-amino-butyric acid (GABA).   
a.From which amino acid is GABA derived (give the name of the amino acid closest in structure to GABA).
b.What is the structural difference between GABA and this amino acid.
c.What is the function of GABA.

Accepted Answer

a.glutamate
b.GABA is missing

Question 20

Questions are based on the diagram shown below.  
-What is the name of the N-terminal amino acid in the peptide shown above?

Accepted Answer

A) cysteine 
B) methionine 
C) valine 
D) alanine 
E) tryptophan 
A) cysteine 
B) methionine 
C) valine 
D) alanine 
E) tryptophan

Exam 4: Amino Acids

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:

Matching -GABA is a neurotransmitter derived from ______.

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

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

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

All the standard amino acids except ____ are optically active.

For the following questions refer to the diagram below -What is the three-letter symbol for the amino acid shown above?

Which of the amino acids represented below has two chiral centers?

Questions are based on the diagram below. -What is the three-letter symbol of the N-terminal amino acid in the structure shown above?

Which of the five amino acids shown below has 2 chiral centers?

Questions are based on the diagram below. -What is the name of this molecule?

The pK1,pK2,and pKR for the amino acid arginine are 1.8,9.0,and 12.5,respectively.At pH 7.0 arginine would be charged predominantly as follows:

Matching -Biological systems usually produce a single enantiomer,whereas chemical synthesis produces a ______.

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

The isoelectronic point of an amino acid is the point where

Which of the following amino acids has a sulfur atom in its side chain?

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

The peptide AYDG has an N-terminal _________ residue.

The picture below shows the structure of γ\gammaγ -amino-butyric acid (GABA). a.From which amino acid is GABA derived (give the name of the amino acid closest in structure to GABA). b.What is the structural difference between GABA and this amino acid. c.What is the function of GABA.

Questions are based on the diagram shown below. -What is the name of the N-terminal amino acid in the peptide shown above?

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 aspartic acid are 2.0,9.9,and 3.9,respectively.At pH 7.0,aspartic acid would be charged predominantly as follows:

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

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

The pK₁,pK₂,and pK_R for the amino acid arginine are 1.8,9.0,and 12.5,respectively.At pH 7.0 arginine would be charged predominantly as follows: