Question 1

Describe the structures of the amino acids phenylalanine and aspartate in the ionization state you would expect at pH 7.0. Why is aspartate very soluble in water, whereas phenylalanine is much less soluble?

Accepted Answer

At pH 7.0, phenylalanine is expected to ...

Question 2

Hydrolysis of peptide bonds is an exergonic reaction. Why, then, are peptide bonds quite stable?

Accepted Answer

Hydrolysis of peptide bonds is indeed an...

Question 3

In a mixture of the five proteins listed below, which should elute second in size-exclusion (gel- filtration)  chromatography?

Accepted Answer

A)   cytochrome c Mr = 13,000
B)   immunoglobulin G Mr = 145,000
C)   ribonuclease A Mr = 13,700
D)   RNA polymerase Mr = 450,000
E)   serum albumin Mr = 68,500F) D) and E)
G) A) and D)

Question 4

Why can only some amino acids be used to measure protein concentration based on absorption of UV light?

Accepted Answer

A)   Only some amino acids are aromatic.
B)   Only some amino acids are positively charged.
C)   Only some amino acids are strongly hydrophobic.
D)   Only some amino acids are strongly hydrophilic.
E)   Only some amino acids are negatively charged.F) All of the above
G) C) and E)

Question 5

Which of the following CORRECTLY matches the amino acid name with its one letter abbreviation?

Accepted Answer

A)   tyrosine, T
B)   lysine, L
C)   phenylalanine, P
D)   aspartic acid, D
E)   proline, RF) A) and B)
G) All of the above

Question 6

By adding SDS (sodium dodecyl sulfate)  during the electrophoresis of proteins, it is possible to:

Accepted Answer

A)   determine a protein's isoelectric point.
B)   determine an enzyme's specific activity.
C)   determine the amino acid composition of the protein.
D)   preserve a protein's native structure and biological activity.
E)   separate proteins exclusively on the basis of molecular weight.F) A) and E)
G) A) and B)

Question 7

Which type of structure refers to particularly stable arrangements of amino acid residues in a protein that give rise to recurring patterns?

Accepted Answer

A)   primary structure
B)   secondary structure
C)   tertiary structure
D)   quaternary structure
E)   None of the answers is correct.F) A) and D)
G) All of the above

Question 8

Which of the lanes in the gel below would represent an "uninduced" sample?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5F) A) and D)
G) C) and E)

Question 9

The chirality of an amino acid results from the fact that its  α\alphaα  carbon:

Accepted Answer

A)   has no net charge.
B)   is a carboxylic acid.
C)   is bonded to four different chemical groups.
D)   is in the L absolute configuration in naturally occurring proteins.
E)   is symmetric. F) A) and E)
G) A) and B)

Question 10

Provide a brief definition for a polymorphic protein.

Accepted Answer

A polymorphic protein is a protein that ...

Question 11

An octapeptide composed of four repeating glycylalanyl units has:

Accepted Answer

A)   one free amino group on an alanyl residue.
B)   one free amino group on an alanyl residue and one free carboxyl group on a glycyl residue.
C)   one free amino group on a glycyl residue and one free carboxyl group on an alanyl residue.
D)   two free amino and two free carboxyl groups.
E)   two free carboxyl groups, both on glycyl residues.F) B) and E)
G) D) and E)

Question 12

Selective precipitation of a protein from a crude extract is MOST effective by which molecule?

Accepted Answer

A)   ammonium sulfate
B)   urea
C)   sodium dodecyl sulfate
D)   EDTA (ethylenediaminetetraacetic acid) 
E)   All of the answers are correct.F) A) and B)
G) C) and D)

Question 13

What is the structure components of Gly-Ala-Glu in the ionic form that predominates at pH 7.

Accepted Answer

At pH 7, which is considered a neutral p...

Question 14

According to the table, size-exclusion (gel-filtration)  chromatography could NOT be used to separate which protein mixture? Protein
MW
PI
A
12,500
3) 2
B
13,200
5) 7
C
13,500
10) 5
D
25,200
6) 3
E
36,900
5) 8
F
78,400
6) 1

Accepted Answer

A)   proteins A, D, and F
B)   proteins C, E, and F
C)   proteins B, E, and F
D)   proteins A, B, and C
E)   All of the answers are correct.F) A) and B)
G) All of the above

Question 15

Conjugated proteins contain chemical substituents in addition to amino acids. List three classes of conjugated proteins and identify the type of prosthetic group associated with each one.

Accepted Answer

1. Glycoproteins - These proteins have c...

Question 16

The term specific activity differs from the term activity in that specific activity:

Accepted Answer

A)   is measured only under optimal conditions.
B)   is the activity (enzyme units)  in a milligram of protein.
C)   is the activity (enzyme units)  of a specific protein.
D)   refers only to a purified protein.
E)   refers to proteins other than enzymes.F) B) and C)
G) A) and B)

Question 17

The functional differences, as well as differences in three-dimensional structures, between two different enzymes from E. coli result directly from their different:

Accepted Answer

A)   affinities for ATP.
B)   amino acid sequences.
C)   roles in DNA metabolism.
D)   roles in the metabolism of E. coli.
E)   secondary structures.F) A) and B)
G) B) and D)

Question 18

Which type of structure describes the overall three-dimensional folding of a polypeptide?

Accepted Answer

A)   primary structure
B)   secondary structure
C)   tertiary structure
D)   quaternary structure
E)   None of the answers is correct.F) C) and E)
G) B) and D)

Question 19

According to the diagram, which estimate is BEST of this amino acid's isoelectric point?

Accepted Answer

A)   0.5
B)   1
C)   1.5
D)   6
E)   11F) A) and E)
G) A) and D)

Question 20

Name two uncommon amino acids that occur in proteins. By what route do they get into proteins?

Accepted Answer

Two uncommon amino acids that occur in p...

Exam 3: Amino Acids, Peptides, and Proteins

According to the table, size-exclusion (gel-filtration) chromatography could NOT be used to separate which protein mixture? Protein MW PI A 12,500 3) 2 B 13,200 5) 7 C 13,500 10) 5 D 25,200 6) 3 E 36,900 5) 8 F 78,400 6) 1

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An octapeptide composed of four repeating glycylalanyl units has:

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Conjugated proteins contain chemical substituents in addition to amino acids. List three classes of conjugated proteins and identify the type of prosthetic group associated with each one.

Correct AnswerAnswered by ExamLex AI1. Glycoproteins - These proteins have c...View AnswerShow Answer

The term specific activity differs from the term activity in that specific activity:

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Which type of structure refers to particularly stable arrangements of amino acid residues in a protein that give rise to recurring patterns?

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Provide a brief definition for a polymorphic protein.

Correct AnswerAnswered by ExamLex AIA polymorphic protein is a protein that ...View AnswerShow Answer

Name two uncommon amino acids that occur in proteins. By what route do they get into proteins?

Correct AnswerAnswered by ExamLex AITwo uncommon amino acids that occur in p...View AnswerShow Answer

Why can only some amino acids be used to measure protein concentration based on absorption of UV light?

Correct AnswerverifiedShow Answer

In a mixture of the five proteins listed below, which should elute second in size-exclusion (gel- filtration) chromatography?

Correct AnswerverifiedShow Answer

Selective precipitation of a protein from a crude extract is MOST effective by which molecule?

Correct AnswerverifiedShow Answer

Which of the lanes in the gel below would represent an "uninduced" sample?

Correct AnswerverifiedShow Answer

The functional differences, as well as differences in three-dimensional structures, between two different enzymes from E. coli result directly from their different:

Correct AnswerverifiedShow Answer

Hydrolysis of peptide bonds is an exergonic reaction. Why, then, are peptide bonds quite stable?

Correct AnswerAnswered by ExamLex AIHydrolysis of peptide bonds is indeed an...View AnswerShow Answer

According to the diagram, which estimate is BEST of this amino acid's isoelectric point?

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Describe the structures of the amino acids phenylalanine and aspartate in the ionization state you would expect at pH 7.0. Why is aspartate very soluble in water, whereas phenylalanine is much less soluble?

Correct AnswerAnswered by ExamLex AIAt pH 7.0, phenylalanine is expected to ...View AnswerShow Answer

Which of the following CORRECTLY matches the amino acid name with its one letter abbreviation?

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The chirality of an amino acid results from the fact that its α\alphaα carbon:

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What is the structure components of Gly-Ala-Glu in the ionic form that predominates at pH 7.

Correct AnswerAnswered by ExamLex AIAt pH 7, which is considered a neutral p...View AnswerShow Answer

By adding SDS (sodium dodecyl sulfate) during the electrophoresis of proteins, it is possible to:

Correct AnswerverifiedShow Answer

Which type of structure describes the overall three-dimensional folding of a polypeptide?

Correct AnswerverifiedShow Answer

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1. Glycoproteins - These proteins have c...
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Answered by ExamLex AI
A polymorphic protein is a protein that ...
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Two uncommon amino acids that occur in p...
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Hydrolysis of peptide bonds is indeed an...
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Correct Answer
Answered by ExamLex AI
At pH 7.0, phenylalanine is expected to ...
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The chirality of an amino acid results from the fact that its $\alpha$ carbon:

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At pH 7, which is considered a neutral p...
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Correct Answer
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