Question 1

At pH 7.0,converting a proline to hydroxyproline,will have what effect on the overall charge of the protein containing it?

Accepted Answer

A) It will become more negative 
B) It will become more positive. 
C) It will stay the same. 
D) There is not enough information to answer the question. 
E) The answer depends on the salt concentration. 
A) It will become more negative 
B) It will become more positive. 
C) It will stay the same. 
D) There is not enough information to answer the question. 
E) The answer depends on the salt concentration. C

Question 2

To determine the isoelectric point of a protein,first establish that a gel:

Accepted Answer

A) contains a denaturing detergent that can distribute uniform negative charges over the protein's surface. 
B) exhibits a stable pH gradient when ampholytes become distributed in an electric field. 
C) is washed with an antibody specific to the protein of interest. 
D) neutralizes all ionic groups on a protein by titrating them with strong bases. 
E) relates the unknown protein to a series of protein markers with known molecular weights,Mr. 
A) contains a denaturing detergent that can distribute uniform negative charges over the protein's surface. 
B) exhibits a stable pH gradient when ampholytes become distributed in an electric field. 
C) is washed with an antibody specific to the protein of interest. 
D) neutralizes all ionic groups on a protein by titrating them with strong bases. 
E) relates the unknown protein to a series of protein markers with known molecular weights,Mr. B

Question 3

Define the primary structure of a protein.

Accepted Answer

The primary structure of a protein is its unique sequence of amino acids and any disulfide bridges present in the native structure,that is,its covalent bond structure.

Question 4

Of the 20 standard amino acids,only ___________ is not optically active.The reason is that its side chain ___________.

Accepted Answer

A) alanine;is a simple methyl group 
B) glycine;is a hydrogen atom 
C) glycine;is unbranched 
D) lysine;contains only nitrogen 
E) proline;forms a covalent bond with the amino group 
A) alanine;is a simple methyl group 
B) glycine;is a hydrogen atom 
C) glycine;is unbranched 
D) lysine;contains only nitrogen 
E) proline;forms a covalent bond with the amino group

Question 5

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 6

One method used to prevent disulfide bond interference with protein sequencing procedures is:

Accepted Answer

A) cleaving proteins with proteases that specifically recognize disulfide bonds. 
B) protecting the disulfide bridge against spontaneous reduction to cysteinyl sulfhydryl groups. 
C) reducing disulfide bridges and preventing their re-formation by further modifying the -SH groups. 
D) removing cystines from protein sequences by proteolytic cleavage. 
E) sequencing proteins that do not contain cysteinyl residues. 
A) cleaving proteins with proteases that specifically recognize disulfide bonds. 
B) protecting the disulfide bridge against spontaneous reduction to cysteinyl sulfhydryl groups. 
C) reducing disulfide bridges and preventing their re-formation by further modifying the -SH groups. 
D) removing cystines from protein sequences by proteolytic cleavage. 
E) sequencing proteins that do not contain cysteinyl residues.

Question 7

A major advance in the application of mass spectrometry to macromolecules came with the development of techniques to overcome which of the following problems?

Accepted Answer

A) Macromolecules were insoluble in the solvents used in mass spectrometry. 
B) Mass spectrometric analyses of macromolecules were too complex to interpret. 
C) Mass spectrometric analysis involved molecules in the gas phase. 
D) Most macromolecules could not be purified to the degree required for mass spectrometric analysis. 
E) The specialized instruments required were prohibitively expensive. 
A) Macromolecules were insoluble in the solvents used in mass spectrometry. 
B) Mass spectrometric analyses of macromolecules were too complex to interpret. 
C) Mass spectrometric analysis involved molecules in the gas phase. 
D) Most macromolecules could not be purified to the degree required for mass spectrometric analysis. 
E) The specialized instruments required were prohibitively expensive.

Question 8

As more OH- equivalents (base)are added to an amino acid solution,what titration reaction will occur around pH = 9.5?

Accepted Answer

Around pH = 9.5,the -NH<sub>3<

Question 9

Briefly describe the five major groupings of amino acids.

Accepted Answer

Amino acids may be categorized

Question 10

In one or two sentences,describe the usefulness of each of the following reagents or reactions in the analysis of protein structure:
(a)Edman reagent (phenylisothiocyanate)
(b)protease
(c)reducing agent (dithiothreitol or $\beta$-mercaptoethanol)

Accepted Answer

(a)Used in determination of the amino ac

Question 11

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

Accepted Answer

Some examples are 4-hydroxyproline,5-hyd

Question 12

If the average molecular weight of the 20 standard amino acids is 138,why do biochemists divide a protein's molecular weight by 110 to estimate its number of amino acid residues?

Accepted Answer

For each peptide bond formed,a molecule

Question 13

What is the approximate charge difference between glutamic acid and $\alpha$-ketoglutarate at pH 9.5?

Accepted Answer

A) 0 
B) ½ 
C) 1 
D) 1½ 
E) 2 
A) 0 
B) ½ 
C) 1 
D) 1½ 
E) 2

Question 14

Prosthetic groups in the class of proteins known as glycoproteins are composed of:

Accepted Answer

A) carbohydrates. 
B) flavin nucleotides. 
C) lipids. 
D) metals . 
E) phosphates. 
A) carbohydrates. 
B) flavin nucleotides. 
C) lipids. 
D) metals . 
E) phosphates.

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

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.

Question 17

What is the uniquely important acid-base characteristic of the histidine R group?

Accepted Answer

Only the imidazole ring of the

Question 18

You are given a solution containing an enzyme that converts B into A.Describe what you would do to determine the specific activity of this enzyme solution.

Accepted Answer

First,add a known volume of the enzyme s

Question 19

The formation of a peptide bond between two amino acids is an example of a(n)______________ reaction.

Accepted Answer

A) cleavage 
B) condensation 
C) group transfer 
D) isomerization 
E) oxidation reduction 
A) cleavage 
B) condensation 
C) group transfer 
D) isomerization 
E) oxidation reduction

Question 20

For each of these methods of separating proteins,describe the principle of the method,and tell what property of proteins allows their separation by this technique.
(a)ion-exchange chromatography
(b)size-exclusion (gel filtration)chromatography
(c)affinity chromatography

Accepted Answer

(a)Ion-exchange chromatography separates

Exam 3: Amino Acids, peptides, and Proteins

At pH 7.0,converting a proline to hydroxyproline,will have what effect on the overall charge of the protein containing it?

To determine the isoelectric point of a protein,first establish that a gel:

Define the primary structure of a protein.

Of the 20 standard amino acids,only ___________ is not optically active.The reason is that its side chain ___________.

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

One method used to prevent disulfide bond interference with protein sequencing procedures is:

A major advance in the application of mass spectrometry to macromolecules came with the development of techniques to overcome which of the following problems?

As more OH- equivalents (base)are added to an amino acid solution,what titration reaction will occur around pH = 9.5?

Briefly describe the five major groupings of amino acids.

In one or two sentences,describe the usefulness of each of the following reagents or reactions in the analysis of protein structure: (a)Edman reagent (phenylisothiocyanate) (b)protease (c)reducing agent (dithiothreitol or β\betaβ -mercaptoethanol)

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

If the average molecular weight of the 20 standard amino acids is 138,why do biochemists divide a protein's molecular weight by 110 to estimate its number of amino acid residues?

What is the approximate charge difference between glutamic acid and α\alphaα -ketoglutarate at pH 9.5?

Prosthetic groups in the class of proteins known as glycoproteins are composed of:

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

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

What is the uniquely important acid-base characteristic of the histidine R group?

You are given a solution containing an enzyme that converts B into A.Describe what you would do to determine the specific activity of this enzyme solution.

The formation of a peptide bond between two amino acids is an example of a(n)______________ reaction.

For each of these methods of separating proteins,describe the principle of the method,and tell what property of proteins allows their separation by this technique. (a)ion-exchange chromatography (b)size-exclusion (gel filtration)chromatography (c)affinity chromatography

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

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

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Of the 20 standard amino acids,only _ is not optically active.The reason is that its side chain _.

As more OH^- equivalents (base)are added to an amino acid solution,what titration reaction will occur around pH = 9.5?

In one or two sentences,describe the usefulness of each of the following reagents or reactions in the analysis of protein structure: (a)Edman reagent (phenylisothiocyanate) (b)protease (c)reducing agent (dithiothreitol or $\beta$ -mercaptoethanol)

What is the approximate charge difference between glutamic acid and $\alpha$ -ketoglutarate at pH 9.5?