Question 1

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. 
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.

Question 2

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

Question 3

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. 
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.

Question 4

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 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 = 68,500 
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 = 68,500

Question 6

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, R 
A)  tyrosine, T 
B)  lysine, L 
C)  phenylalanine, P 
D)  aspartic acid, D 
E)  proline, R

Question 7

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 8

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

Question 9

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

Question 10

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 11

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. 
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.

Question 12

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. 
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.

Question 13

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 14

Provide a brief definition for a polymorphic protein.

Accepted Answer

A polymorphic protein is a protein that

Question 15

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. 
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.

Question 16

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 17

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

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 18

The chirality of an amino acid results from the fact that its $\alpha$ 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. 
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.

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)  11 
A)  0.5 
B)  1 
C)  1.5 
D)  6 
E)  11

Question 20

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

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?

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

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

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.

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

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

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

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

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

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

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

An octapeptide composed of four repeating glycylalanyl units has:

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

Provide a brief definition for a polymorphic protein.

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

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?

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

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

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

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

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

The chirality of an amino acid results from the fact that its $\alpha$ carbon: