Question 1

The C-terminal residue of a polypeptide can be determined by first cleaving the polypeptide with:

Accepted Answer

A)  chymotrypsin. 
B)  carboxypeptidase. 
C)  trypsin. 
D)  CNBr. 
E)  none of the above. 
A)  chymotrypsin. 
B)  carboxypeptidase. 
C)  trypsin. 
D)  CNBr. 
E)  none of the above. B

Question 2

What is the overall net charge on the peptide lys-lys-ser-glu at pH 7.0?

Accepted Answer

A)  +2 
B)  +1 
C)  0 
D)  −1 
E)  −2 
A)  +2 
B)  +1 
C)  0 
D)  −1 
E)  −2 B

Question 3

α-Helix and β-strand are components of ____ structure

Accepted Answer

A)  primary 
B)  secondary 
C)  tertiary 
D)  quaternary 
E)  all are true 
A)  primary 
B)  secondary 
C)  tertiary 
D)  quaternary 
E)  all are true B

Question 4

Explain the significance of the proteome.​

Accepted Answer

An accurate reflection of what a cell is

Question 5

____ is specific in hydrolyzing only peptide bonds in which the carboxyl function is contributed by an arginine or a lysine residue.

Accepted Answer

A)  Chymotrypsin 
B)  Carboxypeptidase 
C)  Trypsin 
D)  CNBr 
E)  None of the above. 
A)  Chymotrypsin 
B)  Carboxypeptidase 
C)  Trypsin 
D)  CNBr 
E)  None of the above.

Question 6

Proteins with two different polypeptide chains are:

Accepted Answer

A)  monomeric proteins. 
B)  trimeric proteins. 
C)  homodimeric proteins. 
D)  heterodimeric proteins. 
E)  none of the above. 
A)  monomeric proteins. 
B)  trimeric proteins. 
C)  homodimeric proteins. 
D)  heterodimeric proteins. 
E)  none of the above.

Question 7

Insulin is a polypeptide hormone that contains two short polypeptide chains linked by two interstrand disulfide bonds. The most logical order of events to perform in order to sequence this protein would be:
A.The peptides are reduced with mercaptoethanol.
B.The peptides are sequenced using Edman chemistry.
C.The peptides are separated by chromatography techniques.
D.The peptides are alkylated with iodoacetamide.

Accepted Answer

A)  A, D, C, B 
B)  C, A, D, B 
C)  C, B, A, D 
D)  A, B, C, D 
E)  A, C, D, B 
A)  A, D, C, B 
B)  C, A, D, B 
C)  C, B, A, D 
D)  A, B, C, D 
E)  A, C, D, B

Question 8

Which of the following reagents is correctly defined?

Accepted Answer

A)  iodoacetic acid: reduces disulfide bonds 
B)  guanadinium hydrochloride: disrupts ionic interactions and hydrogen bonds 
C)  phenylisothiocyanate: reacts with free carboxyl groups 
D)  cyanogen bromide: reacts with internal cysteine residues 
E)  performic acid: reacts with free cysteine residues 
A)  iodoacetic acid: reduces disulfide bonds 
B)  guanadinium hydrochloride: disrupts ionic interactions and hydrogen bonds 
C)  phenylisothiocyanate: reacts with free carboxyl groups 
D)  cyanogen bromide: reacts with internal cysteine residues 
E)  performic acid: reacts with free cysteine residues

Question 9

The diversity in hemoglobin mutants indicates that:

Accepted Answer

A)  any amino acid change is relatively important. 
B)  any amino acid change is lethal to the organism. 
C)  specific amino acid changes drastically alter one or more functions of a protein. 
D)  any amino acid change will have the same effect on the protein function. 
E)  All are true. 
A)  any amino acid change is relatively important. 
B)  any amino acid change is lethal to the organism. 
C)  specific amino acid changes drastically alter one or more functions of a protein. 
D)  any amino acid change will have the same effect on the protein function. 
E)  All are true.

Question 10

A gene can be defined as:

Accepted Answer

A)  the unique function that some cells have but other cells do not have. 
B)  a specific segment of nucleotide bases in DNA that encode for the synthesis of a particular protein. 
C)  a single strand of DNA that is designated as the sense strand. 
D)  a functional segment of a unique protein. 
E)  the segment of DNA that is changed in a mutation. 
A)  the unique function that some cells have but other cells do not have. 
B)  a specific segment of nucleotide bases in DNA that encode for the synthesis of a particular protein. 
C)  a single strand of DNA that is designated as the sense strand. 
D)  a functional segment of a unique protein. 
E)  the segment of DNA that is changed in a mutation.

Question 11

Which of the following would be a possible amino acid sequence for an oligopeptide given the experimental data below?
1)The amino acid composition is found to be [ala, lys, phe, met, cys, plus some decomposition products].
2)The peptide has a molecular weight around 700 Da and absorbs at 280 nm.
3)Treatment with carboxypeptidase results in tryptophan and a peptidE.4.CNBr treatment yields a tetrapeptide and a dipeptidE.5.Trypsin digestion produces an amino acid and a pentapeptide with met on the amino enD.6.Chymotrypsin digestion yields a dipeptide and a tetrapeptidE.

Accepted Answer

A)  trp-lys-met-cys-met-ala 
B)  lys-met-cys-phe-ala-trp 
C)  trp-ala-phe-cys-met-lys 
D)  lys-ala-cys-phe-met-trp 
E)  lys-met-cys-ala-phe-trp 
A)  trp-lys-met-cys-met-ala 
B)  lys-met-cys-phe-ala-trp 
C)  trp-ala-phe-cys-met-lys 
D)  lys-ala-cys-phe-met-trp 
E)  lys-met-cys-ala-phe-trp

Question 12

Proteins that do NOT perform any obvious chemical transformation, but control the ability of other proteins to carry out their physiological functions are:

Accepted Answer

A)  enzymes. 
B)  regulatory proteins. 
C)  transport proteins. 
D)  storage proteins. 
E)  structural proteins. 
A)  enzymes. 
B)  regulatory proteins. 
C)  transport proteins. 
D)  storage proteins. 
E)  structural proteins.

Question 13

Discuss the computer programs that can align amino acid sequences.​

Accepted Answer

Protein sequence databases provide enorm

Question 14

Membrane proteins differ from globular proteins in that:

Accepted Answer

A)  membrane associated amino acids usually have polar side chains. 
B)  membrane proteins are much more soluble in detergents than water. 
C)  membrane proteins usually have more hydrophobic amino acids. 
D)  globular proteins are water insoluble. 
E)  All are true. 
A)  membrane associated amino acids usually have polar side chains. 
B)  membrane proteins are much more soluble in detergents than water. 
C)  membrane proteins usually have more hydrophobic amino acids. 
D)  globular proteins are water insoluble. 
E)  All are true.

Question 15

All of the statements about the peptide val-asp-trp-asn-ser are correct EXCEPT:

Accepted Answer

A)  This peptide would show a strong absorption band at 280 nm. 
B)  Reaction with chymotrypsin would yield two peptides. 
C)  To synthesize this peptide using the solid phase method of Merrifield, the amino acid directly attached to the resin would be valine. 
D)  After the second round of Edman degradation using the reagent PITC, the PTH-amino acid residue released would be PTH-asp. 
E)  The peptide would be converted to a dipeptide and a tripeptide by chymotrypsin. 
A)  This peptide would show a strong absorption band at 280 nm. 
B)  Reaction with chymotrypsin would yield two peptides. 
C)  To synthesize this peptide using the solid phase method of Merrifield, the amino acid directly attached to the resin would be valine. 
D)  After the second round of Edman degradation using the reagent PITC, the PTH-amino acid residue released would be PTH-asp. 
E)  The peptide would be converted to a dipeptide and a tripeptide by chymotrypsin.

Question 16

The amino acid sequence is NOT:

Accepted Answer

A)  a distinctive characteristic of a polypeptide. 
B)  encoded by the nucleotide sequence of DNA. 
C)  a form of genetic information. 
D)  read from N-terminal end to C-terminal end. 
E)  constant for proteins with the same function from different organisms. 
A)  a distinctive characteristic of a polypeptide. 
B)  encoded by the nucleotide sequence of DNA. 
C)  a form of genetic information. 
D)  read from N-terminal end to C-terminal end. 
E)  constant for proteins with the same function from different organisms.

Question 17

After treating a protein with trypsin, which of the following techniques could be used to determine its identity by peptide mass fingerprinting?

Accepted Answer

A)  NMR 
B)  MALDI-TOF mass spectrometer 
C)  HPLC 
D)  gel electrophoresis 
E)  none of the above 
A)  NMR 
B)  MALDI-TOF mass spectrometer 
C)  HPLC 
D)  gel electrophoresis 
E)  none of the above

Question 18

​Explain the role of trypsin in identifying the primary structure of a protein.

Accepted Answer

Trypsin is a digestive enzyme that is us

Question 19

Discuss the quaternary structure of proteins with an example.​

Accepted Answer

Many proteins consist of two or more int

Question 20

The advantage of treating separate samples of a protein with two or more enzymes when sequencing a protein is that the products are:

Accepted Answer

A)  more homogeneous. 
B)  sequenceable without further chromatography. 
C)  fragments with the same N- and C-terminal amino acids. 
D)  fragments with sequence overlaps. 
E)  all are true. 
A)  more homogeneous. 
B)  sequenceable without further chromatography. 
C)  fragments with the same N- and C-terminal amino acids. 
D)  fragments with sequence overlaps. 
E)  all are true.

Exam 5: Proteins: Their Primary Structure and Biological Functions

The C-terminal residue of a polypeptide can be determined by first cleaving the polypeptide with:

What is the overall net charge on the peptide lys-lys-ser-glu at pH 7.0?

α-Helix and β-strand are components of ____ structure

Explain the significance of the proteome.​

____ is specific in hydrolyzing only peptide bonds in which the carboxyl function is contributed by an arginine or a lysine residue.

Proteins with two different polypeptide chains are:

Which of the following reagents is correctly defined?

The diversity in hemoglobin mutants indicates that:

A gene can be defined as:

Proteins that do NOT perform any obvious chemical transformation, but control the ability of other proteins to carry out their physiological functions are:

Discuss the computer programs that can align amino acid sequences.​

Membrane proteins differ from globular proteins in that:

All of the statements about the peptide val-asp-trp-asn-ser are correct EXCEPT:

The amino acid sequence is NOT:

After treating a protein with trypsin, which of the following techniques could be used to determine its identity by peptide mass fingerprinting?

​Explain the role of trypsin in identifying the primary structure of a protein.

Discuss the quaternary structure of proteins with an example.​

The advantage of treating separate samples of a protein with two or more enzymes when sequencing a protein is that the products are:

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

Explain the significance of the proteome.

Discuss the computer programs that can align amino acid sequences.

Explain the role of trypsin in identifying the primary structure of a protein.

Discuss the quaternary structure of proteins with an example.