Question 1

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) B) and D)
G) C) and D)

Question 2

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) A) and C)

Question 3

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) C) and D)
G) A) and B)

Question 4

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) B) and C)
G) B) and E)

Question 5

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) A) and D)
G) C) and E)

Question 6

Provide a brief definition for a polymorphic protein.

Accepted Answer

A polymorphic protein is a protein that ...

Question 7

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) D) and E)
G) A) and E)

Question 8

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 9

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 D)
G) A) and B)

Question 10

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) A) and B)
G) B) and C)

Question 11

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) A) and D)
G) C) and E)

Question 12

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) C) and E)
G) B) and E)

Question 13

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) B) and C)

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 E)
G) A) and C)

Question 15

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) A) and E)

Question 16

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) B) and E)
G) A) and E)

Question 17

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...

Question 18

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 19

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 20

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 ...

Exam 3: Amino Acids, Peptides, and Proteins

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

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An octapeptide composed of four repeating glycylalanyl units has:

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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

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

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

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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

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

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow 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

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

Correct AnswerverifiedShow Answer

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

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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

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 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

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Provide a brief definition for a polymorphic protein.

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

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow 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
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Correct Answer
Answered by ExamLex AI
At pH 7, which is considered a neutral 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
Answered by ExamLex AI
Two uncommon amino acids that occur in p...
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The chirality of an amino acid results from the fact that its $\alpha$ carbon:

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Correct Answer
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At pH 7.0, phenylalanine is expected to ...
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1. Glycoproteins - These proteins have c...
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Correct Answer
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A polymorphic protein is a protein that ...
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