Question 1

Which of these natural amino acids contains two carboxylic acid groups?

Accepted Answer

A) Aspartic acid 
B) Cysteine 
C) Glutamic acid 
D) Cystine and cysteine 
E) Aspartic acidand glutamic acid 
A) Aspartic acid 
B) Cysteine 
C) Glutamic acid 
D) Cystine and cysteine 
E) Aspartic acidand glutamic acid

Question 2

What is the pI of phenylalanine (pKa1 = 1.8; pKa2= 9.1)?

Accepted Answer

A) 2.3 
B) 1.8 
C) 5.5 
D) 9.1 
E) 10.9 
A) 2.3 
B) 1.8 
C) 5.5 
D) 9.1 
E) 10.9

Question 3

Draw the Fischer projection of a threonine diastereomer,and label the chiral centers as R or S.

Accepted Answer

The answer of Draw the Fischer projection of a threonine...

Question 4

Which of the following would provide a synthesis of phenylalanine?

Accepted Answer

A) Phenylacetaldehyde,NH3,HCN; then H3O+ and heat 
B) Potassium phthalimide,BrCH(CO2C2H5)2; C6H5CH2Br,NaOEt; then NaOH; then HCl,heat 
C) Potassium phthalimide,(C6H5)CH2CH2Br; then KOH/H2O; then HCl,heat 
D) C6H5CH2COOH,SOCl2; then NH3 
E) Two of these choices. 
A) Phenylacetaldehyde,NH3,HCN; then H3O+ and heat 
B) Potassium phthalimide,BrCH(CO2C2H5)2; C6H5CH2Br,NaOEt; then NaOH; then HCl,heat 
C) Potassium phthalimide,(C6H5)CH2CH2Br; then KOH/H2O; then HCl,heat 
D) C6H5CH2COOH,SOCl2; then NH3 
E) Two of these choices.

Question 5

Logically,the following "unnatural" amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs?

Accepted Answer

A) Methionine 
B) Cysteine 
C) Cystine 
D) Tyrosine 
E) It could be substituted for all of these amino acids. 
A) Methionine 
B) Cysteine 
C) Cystine 
D) Tyrosine 
E) It could be substituted for all of these amino acids.

Question 6

Which amino acid is achiral?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 7

Which of these amino acids is(are)R amino acid(s)?

Accepted Answer

A) II and IV 
B) IV and V 
C) I and III 
D) V 
E) All of these are R amino acids. 
A) II and IV 
B) IV and V 
C) I and III 
D) V 
E) All of these are R amino acids.

Question 8

Draw structures to represent what happens when valine is dissolved in a strongly acidic solution (pH=0).

Accepted Answer

The answer of Draw structures to represent what happens when...

Question 9

All reactions that occur in living cells are mediated by biological catalysts called ___.The prevailing hypothesis for enzyme catalysis is called the ___ hypothesis.

Accepted Answer

enzymes; l

Question 10

Show how a Strecker synthesis might be used to prepare phenylalanine starting from phenylacetaldehyde.

Accepted Answer

The answer of Show how a Strecker synthesis might be...

Question 11

What is the pI of the following amino acid?

Accepted Answer

A) 1.2 
B) 3.2 
C) 5.5 
D) 6.2 
E) 7.0 
A) 1.2 
B) 3.2 
C) 5.5 
D) 6.2 
E) 7.0

Question 12

Which of these natural amino acids,when present in a polypeptide,is likely to exhibit significant hydrogen bonding through its side chain?

Accepted Answer

A) Serine 
B) Threonine 
C) Tyrosine 
D) Two of these choices. 
E) All of these choices. 
A) Serine 
B) Threonine 
C) Tyrosine 
D) Two of these choices. 
E) All of these choices.

Question 13

Enzymes catalyze stereospecific reactions.Stereospecific reactions are those that:

Accepted Answer

A) Lead to different stereoisomers from different stereoisomeric substrates. 
B) Lead to the same stereoisomer despite starting with different stereoisomeric substrates. 
C) Both stereoisomers,cis or trans can produce identical products. 
D) Transform different substrates. 
E) Transform one conformer into another conformer by rotation of the bonds. 
A) Lead to different stereoisomers from different stereoisomeric substrates. 
B) Lead to the same stereoisomer despite starting with different stereoisomeric substrates. 
C) Both stereoisomers,cis or trans can produce identical products. 
D) Transform different substrates. 
E) Transform one conformer into another conformer by rotation of the bonds.

Question 14

Which amino acid is unlikely to be found in a natural protein?

Accepted Answer

A) IV 
B) III 
C) II 
D) V 
E) I 
A) IV 
B) III 
C) II 
D) V 
E) I

Question 15

Which one of these amino acids does not give the usual purple color with ninhydrin?

Accepted Answer

A) Histidine 
B) Proline 
C) Tryptophan 
D) Leucine 
E) Aspartic acid 
A) Histidine 
B) Proline 
C) Tryptophan 
D) Leucine 
E) Aspartic acid

Question 16

Which of these amino acids is described as an "essential" amino acid?

Accepted Answer

A) Methionine 
B) Phenylalanine 
C) Isoleucine 
D) Tryptophan 
E) All of these are "essential" amino acids. 
A) Methionine 
B) Phenylalanine 
C) Isoleucine 
D) Tryptophan 
E) All of these are "essential" amino acids.

Question 17

Which amino acid would have its isoelectric point near pH 10?

Accepted Answer

A) Glycine 
B) Tryptophan 
C) Serine 
D) Proline 
E) Lysine 
A) Glycine 
B) Tryptophan 
C) Serine 
D) Proline 
E) Lysine

Question 18

What is the pI of the following amino acid?

Accepted Answer

A) 1.5 
B) 6.3 
C) 5.6 
D) 9.8 
E) 7.2 
A) 1.5 
B) 6.3 
C) 5.6 
D) 9.8 
E) 7.2

Question 19

Which amino acid would have its isoelectric point near pH 10?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 20

Draw structures to represent what happens when lysine is dissolved in a strongly basic solution (pH=14).

Accepted Answer

The answer of Draw structures to represent what happens when...

Exam 24: Amino Acids and Proteins

Which of these natural amino acids contains two carboxylic acid groups?

What is the pI of phenylalanine (pKa1 = 1.8; pKa2= 9.1)?

Draw the Fischer projection of a threonine diastereomer,and label the chiral centers as R or S.

Which of the following would provide a synthesis of phenylalanine?

Logically,the following "unnatural" amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs?

Which amino acid is achiral?

Which of these amino acids is(are)R amino acid(s)?

Draw structures to represent what happens when valine is dissolved in a strongly acidic solution (pH=0).

All reactions that occur in living cells are mediated by biological catalysts called ___.The prevailing hypothesis for enzyme catalysis is called the ___ hypothesis.

Show how a Strecker synthesis might be used to prepare phenylalanine starting from phenylacetaldehyde.

What is the pI of the following amino acid?

Which of these natural amino acids,when present in a polypeptide,is likely to exhibit significant hydrogen bonding through its side chain?

Enzymes catalyze stereospecific reactions.Stereospecific reactions are those that:

Which amino acid is unlikely to be found in a natural protein?

Which one of these amino acids does not give the usual purple color with ninhydrin?

Which of these amino acids is described as an "essential" amino acid?

Which amino acid would have its isoelectric point near pH 10?

What is the pI of the following amino acid?

Which amino acid would have its isoelectric point near pH 10?

Draw structures to represent what happens when lysine is dissolved in a strongly basic solution (pH=14).

The Basics

Families of Carbon

Acids and Bases

Nomenclature and Conformations of Alkanes and Cycloalkanes

Stereochemistry

Nucleophilic Reactions

Alkenes and Alkynes I

Alkenes and Alkynes II

Nuclear Magnetic Resonance and Mass Spectrometry

Radical Reactions

Alcohols and Ethers

Alcohols From Carbonyl Compounds

Conjugated Unsaturated Systems

Aromatic Compounds

Reactions of Aromatic Compounds

Aldehydes and Ketones

Carboxylic Acids and Their Derivatives

Reactions at the Α Carbon of Carbonyl Compounds

Condensation and Conjugate Addition Reactions of Carbonyl Compounds

Amines

Transition Metal Complexes

Carbohydrates

Lipids

Nucleic Acids and Protein Synthesis

Filters

What is the pI of phenylalanine (pK_a1 = 1.8; pK_a2= 9.1)?

All reactions that occur in living cells are mediated by biological catalysts called _.The prevailing hypothesis for enzyme catalysis is called the _ hypothesis.