Question 1

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.

Question 2

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 3

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.

Question 4

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

Accepted Answer

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

Question 5

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

Question 6

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.

Question 7

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.

Question 8

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

Question 9

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

Question 10

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 11

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

Accepted Answer

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

Question 12

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.

Question 13

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

Question 14

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...

Question 15

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 16

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 17

Which amino acid is achiral?

Accepted Answer

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

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

Question 19

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

Accepted Answer

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

Question 20

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.

Exam 24: Amino Acids and Proteins

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct Answerverifiedenzymes; l...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which of the following would provide a synthesis of phenylalanine?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is the pI of the following amino acid?

Correct AnswerverifiedShow Answer

What is the pI of the following amino acid?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Enzymes catalyze stereospecific reactions.Stereospecific reactions are those that:

Correct AnswerverifiedShow Answer

Which amino acid is achiral?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

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enzymes; l...
View Answer

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

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Correct Answer
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