Question 1

This reagent is used to "protect" the amino group of an amino acid which is to be joined to a second amino acid by a peptide bond.

Accepted Answer

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

Question 2

Which amino acid would have its isoelectric point near pH 3?

Accepted Answer

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

Question 3

Which amino acid would not have its isoelectric point in the pH range 5-7?

Accepted Answer

A)  Glycine 
B)  Proline 
C)  Cysteine 
D)  Glutamine 
E)  All of these amino acids have isoelectric point in the pH range 5-7 
A)  Glycine 
B)  Proline 
C)  Cysteine 
D)  Glutamine 
E)  All of these amino acids have isoelectric point in the pH range 5-7

Question 4

What would be the predominant form of lysine in water at pH 14?

Accepted Answer

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

Question 5

The predominant form of aspartic acid in water at pH 1 would be:

Accepted Answer

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

Question 6

What product(s)would you expect from the following reaction?

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 natural amino acids contains an indole ring?

Accepted Answer

A)  Phenylalanine 
B)  Tyrosine 
C)  Tryptophan 
D)  4-Hydroxyproline 
E)  Asparigine 
A)  Phenylalanine 
B)  Tyrosine 
C)  Tryptophan 
D)  4-Hydroxyproline 
E)  Asparigine

Question 8

Which of these natural amino acids contains an amide function?

Accepted Answer

A)  Asparagine 
B)  Proline 
C)  Arginine 
D)  Histidine 
E)  None of these 
A)  Asparagine 
B)  Proline 
C)  Arginine 
D)  Histidine 
E)  None of these

Question 9

Which of these amino acids contains a hydrophobic side chain?

Accepted Answer

A)  Lysine 
B)  Serine 
C)  Methionine 
D)  Arginine 
E)  Cysteine 
A)  Lysine 
B)  Serine 
C)  Methionine 
D)  Arginine 
E)  Cysteine

Question 10

A heptapeptide Ala2,Glu,Phe,Pro,Tyr,Val gives labeled alanine when heated with DNFB followed by hydrolysis.On partial hydrolysis the unlabeled heptapeptide gives the following: Ala·Glu,Pro·Tyr,Ala·Val,Tyr·Ala,Val·Phe·Pro.
What is the amino acid sequence of the heptapeptide?

Accepted Answer

A)  Ala·Phe·Pro·Tyr·Ala·Glu·Val 
B)  Ala·Val·Phe·Pro·Tyr·Ala·Glu 
C)  Ala·Val·Phe·Pro·Tyr·Glu·Ala 
D)  Ala·Val·Phe·Tyr·Pro·Ala·Glu 
E)  Val·Ala·Phe·Tyr·Pro·Ala·Glu 
A)  Ala·Phe·Pro·Tyr·Ala·Glu·Val 
B)  Ala·Val·Phe·Pro·Tyr·Ala·Glu 
C)  Ala·Val·Phe·Pro·Tyr·Glu·Ala 
D)  Ala·Val·Phe·Tyr·Pro·Ala·Glu 
E)  Val·Ala·Phe·Tyr·Pro·Ala·Glu

Question 11

The 22 $\alpha$-amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ____________.

Accepted Answer

neutral,ac

Question 12

The pH at which the concentration of the zwitterionic form (dipolar form)of an amino acid is at its highest and the concentrations of the cationic and anionic forms are equal is called the _____________.

Accepted Answer

The answer of The pH at which the concentration of...

Question 13

The exact sequence of the different $\alpha$-amino acids along the protein chain is called the ________________ of the protein.

Accepted Answer

The answer of The exact sequence of the different $\alpha$-amino...

Question 14

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 10?

Accepted Answer

A)  It must have a hydrophobic side chain 
B)  It must have a hydrophilic side chain 
C)  Its side chain must contain more basic groups then acidic functions 
D)  Its side chain must contain an acidic group 
E)  None of the above is a valid conclusion 
A)  It must have a hydrophobic side chain 
B)  It must have a hydrophilic side chain 
C)  Its side chain must contain more basic groups then acidic functions 
D)  Its side chain must contain an acidic group 
E)  None of the above is a valid conclusion

Question 15

Which amino acid would not have its isoelectric point in the pH range 5-7?

Accepted Answer

A)  Leucine 
B)  Threonine 
C)  Methionine 
D)  Arginine 
E)  Cysteine 
A)  Leucine 
B)  Threonine 
C)  Methionine 
D)  Arginine 
E)  Cysteine

Question 16

Which of these amino acids is formed from a precursor amino acid only after the latter has been incorporated into a polypeptide chain?

Accepted Answer

A)  Serine 
B)  Arginine 
C)  Isoleucine 
D)  Tryptophan 
E)  Hydroxyproline 
A)  Serine 
B)  Arginine 
C)  Isoleucine 
D)  Tryptophan 
E)  Hydroxyproline

Question 17

Give the structure of the aldehyde which,upon treatment with HCN and ammonia,followed by heating with aqueous acid,would afford racemic tryptophan.What is this strategy for the synthesis of $\alpha$-amino acids called?

Accepted Answer

This is ca

Question 18

Why is this sequence,CH2=CHCH2OH + HBr,then CrO3/H2SO4/H2O,finally xs NH3,not a good method for the preparation of L-alanine?

Accepted Answer

A)  NH3 is not sufficiently nucleophilic to perform the final step. 
B)  HBr does not add to substituted alkenes. 
C)  1° alcohols are not oxidized by CrO3 in acidic solution. 
D)  Initial HBr addition produces a racemic intermediate which leads to racemic product. 
E)  Steric hindrance precludes nucleophilic substitution at a 2° carbon atom. 
A)  NH3 is not sufficiently nucleophilic to perform the final step. 
B)  HBr does not add to substituted alkenes. 
C)  1° alcohols are not oxidized by CrO3 in acidic solution. 
D)  Initial HBr addition produces a racemic intermediate which leads to racemic product. 
E)  Steric hindrance precludes nucleophilic substitution at a 2° carbon atom.

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

Which amino acid of a polypeptide would become labeled when the polypeptide is treated with 2,4-dinitrofluorobenzene in base,even though the amino acid is not a terminal amino acid?

Accepted Answer

A)  Lysine 
B)  Glycine 
C)  Alanine 
D)  Phenylalanine 
E)  Leucine 
A)  Lysine 
B)  Glycine 
C)  Alanine 
D)  Phenylalanine 
E)  Leucine

Exam 24: Amino Acids and Proteins

This reagent is used to "protect" the amino group of an amino acid which is to be joined to a second amino acid by a peptide bond.

Which amino acid would have its isoelectric point near pH 3?

Which amino acid would not have its isoelectric point in the pH range 5-7?

What would be the predominant form of lysine in water at pH 14?

The predominant form of aspartic acid in water at pH 1 would be:

What product(s)would you expect from the following reaction?

Which of these natural amino acids contains an indole ring?

Which of these natural amino acids contains an amide function?

Which of these amino acids contains a hydrophobic side chain?

A heptapeptide Ala2,Glu,Phe,Pro,Tyr,Val gives labeled alanine when heated with DNFB followed by hydrolysis.On partial hydrolysis the unlabeled heptapeptide gives the following: Ala·Glu,Pro·Tyr,Ala·Val,Tyr·Ala,Val·Phe·Pro. What is the amino acid sequence of the heptapeptide?

The 22 α\alphaα -amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ____________.

The pH at which the concentration of the zwitterionic form (dipolar form)of an amino acid is at its highest and the concentrations of the cationic and anionic forms are equal is called the _____________.

The exact sequence of the different α\alphaα -amino acids along the protein chain is called the ________________ of the protein.

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 10?

Which amino acid would not have its isoelectric point in the pH range 5-7?

Which of these amino acids is formed from a precursor amino acid only after the latter has been incorporated into a polypeptide chain?

Give the structure of the aldehyde which,upon treatment with HCN and ammonia,followed by heating with aqueous acid,would afford racemic tryptophan.What is this strategy for the synthesis of α\alphaα -amino acids called?

Why is this sequence,CH2=CHCH2OH + HBr,then CrO3/H2SO4/H2O,finally xs NH3,not a good method for the preparation of L-alanine?

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

Which amino acid of a polypeptide would become labeled when the polypeptide is treated with 2,4-dinitrofluorobenzene in base,even though the amino acid is not a terminal amino acid?

Carbon Compounds and Chemical Bonds

Representative Carbon Compounds: Functional Groups, Intermolecular Forces, and Infrared Ir Spectroscopy

An Introduction to Organic Reactions: Acids and Bases

Alkanes: Nomenclature, Conformational Analysis, and an Introduction to Synthesis

Stereochemistry: Chiral Molecules

Ionic Reactions - Nucleophilic Substitution and Elimination Reactions of Alkyl Halides

Alkenes and Alkynes I: Properties and Synthesis, Elimination Reactions of Alkyl Halides

Alkenes and Alkynes Ii: Addition Reactions

Nuclear Magnetic Resonance and Mass Spectrometry: Tools for Structure Determination

Radical Reactions

Alcohols and Ethers

Alcohols From Carbonyl Compounds Oxidation-Reduction and Organometallic Compounds

Conjugated Unsaturated Systems

Aromatic Compounds

Reactions of Aromatic Compounds

Aldehydes and Ketones I Nucleophilic Addition to the Carbonyl Group

Aldehydes and Ketones Ii Aldol Reactions

Carboxylic Acids and Their Derivatives Nucleophilic Addition - Elimination at the Acyl Carbon

Synthesis and Reactions of Beta-Dicarbonyl Compounds: More Chemistry of Enolate Ions

Amines

Phenols and Aryl Halides: Nucleophilic Aromatic Substitution

Carbohydrates

Lipids

Nucleic Acids and Protein Synthesis

Filters

A heptapeptide Ala₂,Glu,Phe,Pro,Tyr,Val gives labeled alanine when heated with DNFB followed by hydrolysis.On partial hydrolysis the unlabeled heptapeptide gives the following: Ala·Glu,Pro·Tyr,Ala·Val,Tyr·Ala,Val·Phe·Pro. What is the amino acid sequence of the heptapeptide?

The 22 $\alpha$ -amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ____________.

The exact sequence of the different $\alpha$ -amino acids along the protein chain is called the ________________ of the protein.

Give the structure of the aldehyde which,upon treatment with HCN and ammonia,followed by heating with aqueous acid,would afford racemic tryptophan.What is this strategy for the synthesis of $\alpha$ -amino acids called?

Why is this sequence,CH₂=CHCH₂OH + HBr,then CrO₃/H₂SO₄/H₂O,finally xs NH₃,not a good method for the preparation of L-alanine?