CHAPTER FIVEAMINO ACIDS, PEPTIDES, AND PROTEINS

1) Which of the following is a function of proteins?

A) DefenseB) Metabolic regulationC) TransportD) CatalysisE) All of the above are correct

Ans E

2) The term protein refers to amino acid polymers with greater than ________amino acids.

A) 10B) 20C) 50D) 70E) 90

Ans C

3) Which of the following is a nonstandard amino acid?

A) GlycineB) CysteineC) 5-HydroxyprolineD) ValineE) Alanine

Ans C

4) Which of the following is a heterocyclic amino acid?

A) AlanineB) ValineC) ProlineD) TyrosineE) Cystine

Ans C

5) Which of the following is not a class of amino acid?

A) Nonpolar and neutralB) Polar and neutralC) AcidicD) BasicE) Asymmetric

Ans E

6) Which of the following amino acids lacks a center of asymmetry?

A) AlanineB) GlycineC) ValineD) IsoleucineE) Aspartic acid

Ans B

7) Given the following pK’s what is the principal form of serine at pH 5?

pKa1 = 2.21 pKa2 = 9.15

A)

B)

C)

D)

H2CCH

CO

O

H

NH3

OH

H

+

+

H2CCH

CO

O

H

NH3

OH

+

+

_H2CCH

CO

O

NH3

OH

H

+

H2CCH

CO

O

H

NH2

OH

E)

Ans E

8) Given the following pKa’s the isoelectric point of serine is ________.pK1 = 2.21 pK2 = 9.15

A) 2.21B) 5.68C) 9.15D) 6.62E)11.36

Ans B

9) Consider the following dipeptide. Which letter indicates a peptide bond

A) AB) BC) CD) DE) E

Ans C

H2CCH

CO

O

NH3

OH

+

_

H

N

C

C

N

C

C

O

H

H

H

H

O

H

H

H

OA

B

C

D

E

10) The amino acid sequence of a polypeptide is referred to as ________structure.

A) PrimaryB) SecondaryC) TertiaryD) QuaternaryE) Peptide

Ans A

11) The overall three-dimensional structure of a polypeptide is referred to as _________ structure.

A) PrimaryB) SecondaryC) TertiaryD) QuaternaryE) Peptide

Ans C

12) Invariant amino acids in a protein are presumed:

A) To be unimportant in the structure and function of the proteinB) To be essential to the structure and function of the proteinC) Always to occur at the beginning of the amino acid sequence of an enzymeD) Always to occur at the end of the amino acid sequence of an enzymeE) To be part of the prosthetic group.

Ans B

13) -pleated sheets are associated with what level of protein structure?

A) PrimaryB) SecondaryC) TertiaryD) QuaternaryE) Superquaternary

Ans B

14) Which of the following amino acids would foster an -helix?

A) GlycineB) AlanineC) ProlineD) TyrosineE) Serine

Ans B

15) The Greek key is associated with which of the following?

A) -helixB) Parallel -pleated sheetsC) Antiparallel -pleated sheetsD) Disulfide bridgesE) Salt bridges

Ans C

16) Which of the following interactions do not stabilize tertiary structure?

A) Hydrophobic interactionsB) Electrostatic interactionsC) Hydrogen bondsD) Covalent bondsE) None of the above

Ans E

17) Detergents denature proteins by disrupting which of the following?

A) Hydrogen bondsB) Disulfide bridgesC) Hydrophobic interactionsD) Salt bridgesE) Both A and B are correct

Ans C

18) Fibrous proteins typically have large amounts of: A) -HelixB) -Pleated sheetsC) Disulfide bridgesD) Salt bridgesE) Both A and B are correct

Ans E

19) The identity and arrangement of amino acids on the surface of a globular protein are important because they may:

A) Interact to form specific binding cavitiesB) Stabilize the tertiary structure of the proteinC) Bind regulatory moleculesD) Both A and C are correctE) All of the above are correct

Ans E

20) Which of the following statements regarding cooperative binding is true?

A) Two or more proteins aid the binding of a ligand.B) The binding of one ligand aids the binding of a second ligandC) The folding of part of a protein aids in the folding of the remainder of the proteinD) All proteins engage in cooperative bindingE) The binding of a cofactor to a protein aids in the binding of a ligand.

Ans B

21) Which of the following statements is true of the Bohr effect?

A) Oxygen is delivered to cells in proportion to their needsB) Binding of protons to hemoglobin molecules facilitates the binding of oxygenC) Metabolic waste products bond to oxyhemoglobinD) A and B are both trueE) All of the above are true

Ans A

22) A polypeptide has a high pI value. Which of the following amino acids are likely to be present?

A) GlycineB) SerineC) ValineD) Aspartic acidE) Arginine

Ans E

23) Structural proteins “freeze” large amounts of water. Which of the following interactions is not likely to be involved in the binding of water?

A) Salt bridgesB) Hydrogen bondingC) Hydrophilic interactionsD) Disulfide bridgesE) Both C and D are correct.

Ans D

24) Why is the peptide bond stronger than the ester bond?

A) Greater electronegativity of nitrogenB) Greater electronegativity of oxygenC) Resonance stabilization of the amide bondD) Increased basicity of nitrogenE) Size of the nitrogen atom compared to the oxygen atom

Ans C

25) Which of the following amino acids would be classified as a nonstandard amino acid

A) TyrosineB) LysineC) CystineD) GlycineE) Arginine

Ans C

26) Given that pK1 = 2.35 and pK2 = 9.69 for alanine. What is its isoelectric point

A) 9.69B) 2.34C) 6.02D) 12.03E) 7.00

Ans C

27) When not at the terminal of a protein which of the following amino acids cannot contribute to the PI of a protein?

A) ArginineB) LysineC) CysteineD) TyrosineE) Alanine

Ans E

28) When part of a polypeptide chain other than the N-terminus, which of the following amino acids can form a aldimines?

A) GlycineB) AlanineC) ProlineD) HistidineE) Lysine

Ans E

29) Collagen is classified as which of the following types of protein?

A) EnzymeB) StructuralC) MovementD) DefenseE) Regulatory

Ans B

30) A prosthetic group is a :

A) Repair enzymeB) Group other than an amino acid that is part of a proteinC) Group that generates the native form of a proteinD) Disulfide linkE) Group that reduces enzyme activity

Ans B

31) The major component of the dry weight of cells is _______.

A) CarbohydrateB) ProteinC) FatsD) MineralsE) The major component will vary from organism to organism

Ans B

32) The total number of proteins that can be produced from any 10 amino acids is?

A) 1020

B) 2010

C) 100D) 200E) 1010

Ans B

33) Schiff bases are also referred to as:

A) AldiminesB) AminesC) CarbinolaminesD) Amino acidsE) Both A and C are correct

Ans A

34) Which of the following amino acids would be found in a -turn?

A) ProlineB) AlanineC) PhenylalanineD) LysineE) Tyrosine

Ans A

35) Which of the following is not a function of IUPs?

A) Signal transductionB) TranscriptionC) TranslationD) Cell proliferationE) Oxygen transport

Ans E

36) The source of energy for motor proteins in addition to ATP is:

A) NAD+

B) GTPC) PEPD) ADPE) PPi

Ans B

37) Keratin is classified as which of the following types of protein?

A) EnzymeB) StructuralC) MovementD) DefenseE) Regulatory

Ans B

38) In which of the following mechanical properties does spider silk exceed all synthetic fibers?

A) ToughnessB) Tensile strengthC) ElasticityD) ResilienceE) All of the above

Ans E

39) Which of the following is a hydrophobic amino acid?

A) GlycineB) SerineC) LysineD) PhenylalanineE) Both C and D are hydrophobic

Ans E

40) A conjugated protein consists of a simple protein combined with a _________.

A) ApoproteinB) HoloproteinC) Prosthetic groupD) Answers B and C are correctE) All of the above are correct

Ans C

41) Which of the following amino acids is not one of the twenty standard amino acids?

A) GlycineB) PhenylalanineC) TyrosineD) CystineE) Arginine

Ans D

42) How many standard amino acids are there?

A) 5B) 17C) 20D) 12E) 32

Ans C

43) How many octapeptides containing only two amino acids are possible?

A) 8B) 148C) 16D) 256E) 35

Ans D

44) Amino acid polymers with a molecular weight between several thousand and several million Daltons are called

A) DipeptidesB) PolypeptidesC) ProteinsD) PeptidesE) None of the above

Ans C

45) Which of the following is not a function of proteins?

A) Structural materialsB) CatalystC) Metabolic regulationD) TransportE) All of the above are functions of proteins

Ans E

46) Which of the following is a polar amino acid?

A) PhenylalanineB) TyrosineC) MethionineD) TryptophanE) Proline

Ans B

CHAPTER NINETEENPROTEIN SYNTHESIS

1) The Shine-Dalgarno sequence is a

A) Prokaryotic mRNA sequence that binds IF-3B) Prokaryotic mRNA sequence that binds 16S rRNA of the small ribosomal subunitC) Prokaryotic mRNA sequence that binds the 16S RNA of the large ribosomal subunitD) Eukaryotic rRNA sequence that binds the AUG codon of mRNAE) None of the above are correct

Ans B

2) The initiation phase of prokaryotic translation ends as the GTP molecule bound to ________ is hydrolysed to GDP and Pi

A) IF-1B) IF-2C) IF-3D) IF-4E) None of the above are correct

Ans B

3) During the elongation phase of prokaryotic translation the aminoacyl-tRNA must first bind _________ before it can be positioned in the A site.

A) EF-TsB) EF-TuC) EF-Ts-GDPD) EF-Ts-GTPE) EF-Tu-GTP

Ans E

4) ________ is an enzymatic activity that hydrolyses the bond linking the completed polypeptide chain and the P site tRNA

A) RF-1B) EF-GC) Peptidyl transferaseD) Ribosomal esteraseE) Signal peptidase

Ans C5) Prominent prokaryotic posttanslational modifications include all of the following except __________.

A) GlycosylationB) MethylationC) Proteolytic processingD) PrenylationE) Phosphorylation

Ans D

6) In prokaryotes most of the control of protein synthesis occurs at the level of ______.

A) TranslationB) TranscriptionC) ReplicationD) Reverse transcriptionE) Posttranslational modification

Ans B

7) The enzymatic activities coded by the lac operon include all of the following except:

A) Thiogalactoside transacylaseB) Lactose transferaseC) -GalactosidaseD) Galactose permeaseE) None of the above are correct

Ans B

8) Translocation in eukaryotes requires _____, which is a GTP binding protein.

A) eEF-1B) eEF-2C) eEF-3D) eEF-4E) None of the above are correct

Ans B

9) In eukaryotic translation the 40S complex binds the 60S subunit to form the _______initiation complex.

A) 80SB) 88SC) 90SD) 100SE) 108S

Ans A

10) ________ provides the energy needed to move the ribosome along the mRNA.

A) ATPB) GTPC) UTPD) TTPE) All of the above are correct

Ans B

11) Polypeptides containing signal peptides are called ________.

A) ZymogensB) PreproproteinsC) ProproteinsD) All of the above are correctE) None of the above are correct

Ans B

12) Phosphorylated dolichol, a polyisoprenoid found in ER membrane, is involved in

A) Polypeptide synthesisB) Proteolytic cleavage reactionsC) Lipophillic modification reactionsD) Hydroxylation reactionsE) Glycosylation reactions

Ans E

13) All of the following are involved in signal peptide processing except

A) Ribosomal polypeptide translocation factorB) SRP receptor proteinC) Docking proteinD) TransloconE) Stop transfer signal

Ans A

14) The phrase “global control” refers to

A) Large alterations in mRNA translation patternsB) Large alterations in mRNA synthesis patternsC) Specific changes in rRNA synthesisD) Specific changes in mRNA synthesisE) Changes in transcript localization patterns

Ans A

15) Translational frameshifting

A) Results in the synthesis of more than one polypeptide from a single mRNAB) Has been observed in cells infected by retrovirusesC) Is the result of a +1 or –1 change in the reading frame of an mRNAD) Both A and C are correctE) All of the above are correct

Ans E

16) All of the following statements concerning eukaryotic mRNA are true except

A) Only a small portion of mRNA enters the cytoplasmB) Most hnRNA is processed into mRNAC) Export of mRNA through muclear pores is carefully controlledD) mRNA export usually requires a 5’-cap and a 3’-poly A tailE) None of the above are correct

Ans B

17) Eukaryotic mRNA stability involves

A) Reversible adenylationB) The length of poly (A) tailsC) The binding of specific proteins to certain mRNA sequencesD) The action of various nucleasesE) All of the above are correct

Ans E

18) _______ are a group of molecules that mediate protein folding.

A) Hsp 70sB) ChaparoninsC) Docking proteinD) Both A and B are correctE) All of the above are correct

Ans D

19) The mRNA that codes for ________ possesses an iron response element.

A) CollagenB) ElastinC) GlobinD) FerritinE) Thiogalactoside transacetylase

Ans D

20) Chloramphenicol is an antibiotic that

A) Inhibits prokaryotic peptidyl transferaseB) Causes mRNA misreading via binding to the 30S subunitC) Interferes with aminoacyl-tRNA binding via binding to 30S subunitD) Inhibits eukaryotic peptidyl transferaseE) Inhibits prokaryotic peptide chain elongation

Ans A

21) Cycloheximide is an antibiotic that

A) Inhibits prokaryotic peptidyl transferaseB) Causes mRNA misreading via binding to 30s subunitC) Interferes with aminoacyl-tRNA binding via binding to the 30S subunitD) Inhibits eukaryotic peptidyl transferaseE) Inhibits prokaryotic peptide chain elongation

Ans D

22) Tetracycline is an antibiotic that

A) Inhibits prokaryotic peptidyl transferaseB) Causes mRNA misreading via binding to 30S subunitC) Interferes with aminoacyl-tRNA binding to the 30S subunitD) Inhibits eukaryotic peptidyl transferaseE) Inhibits prokaryotic peptide chain elongation

Ans C

23) Erythromycin is an antibiotic that

A) Inhibits prokaryotic peptidyl transferaseB) Causes mRNA misreading via binding to 30S subunitC) Interferes with aminoacyl-tRNA binding via binding to the 30S subunitD) Inhibits eukaryotic peptidyl transferaseE) Inhibits prokaryotic peptide chain elongation

Ans E

24) Which of the following antibiotics would be most toxic for humans

A) TetracyclineB) ChloramphenicolC) StreptomcyinD) CycloheximideE) Erythromycin

Ans D

25) Ribonucleoprotein particles

A) Contain an mRNAB) Contain several types of proteinC) Are found only in prokaryotesD) Both A and B are correctE) All of the above are correct

Ans D

26) _________ is a translation factor that possesses a unique histidine residue that can be modified to form dipthamide

A) IF-2B) EF-TuC) EF-TsD) eEF-1E) eEF-2

Ans E

27) Hydroxylation is a posttranslational modification that

A) Requires ascorbic acidB) Is catalyzed by several mixed function oxidasesC) Is required for the structural integrity of globinD) Both A and B are correctE) All of the above are correct

Ans D

28) In prokaryotes posttranslational methylation reactions are associated with

A) Signal transductionB) ChemotaxisC) S-AdenosylmethionineD) All of the above are correctE) None of the above are correct

Ans D

29) The half-lives of prokaryotic mRNA usually varies between

A) 1 and 3 secondsB) 1 and 3 minutesC) 1 and 3 hoursD) 3 and 10 hoursE) None of the above are correct

Ans B

30) Peptidyl transferase is an enzymatic activity that

A) Catalyzes the release of polypeptides from the ribosomesB) Is found in an rRNA component of ribosomesC) Catalyzes the nucleophilic attack of the A site -amino group on the carbonyl carbon of the P side amino acidD) Catalyses peptide bond formationE) All of the above are correct

Ans E

31) Energy for ribosome function is provided by

A) ATPB) GTPC) PhosphoenolpyruvateD) Hydrolysis of pyrophosphateE) Both A and B are correct

Ans B

32) Unlike the protein synthesis mechanism in the cytoplasm of eukaryotic cells, mitochondria have _______ stop codes.

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

Ans D

33) An analysis of the wobble hypothesis suggests that a minimum of _______ RNA’s are required to translate all 61 codons plus one for a start codon.

A) 22B) 32C) 16D) 62E) 30

Ans B

34) Translation begins with

A) ElongationB) InitiationC) TerminationD) TargetingE) tRNA synthesis

Ans B

35) Which of the following is a type of posttranslational modification?

A) Removal of signal peptidesB) CarboxylationC) MethylationD) PhosphorylationE) All of the above

Ans E

36) Protein synthesis requires _____ high energy phosphate bonds per peptide bond.

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

Ans D

37) An amino acid coded for by a stop signal is

A) PyrrolysineB) LysineC) CysteineD) SelenocysteineE) Both A and D are correct

Ans E

38) In eukaryotes which of the following amino acids is often hydroxylated after protein synthesis?

A) ProlineB) TyrosoneC) ArginineD) MethionineE) All of the above

Ans A

39) Which of the following amino acids is sometimes carboxylated after protein synthesis in eukaryotes

A) GlutamateB) AspartateC) PhenylalanineD) LysineE) Arginine

Ans A

40) Prokaryotes exclusively use which of the following translational control mechanisms?

A) Negative translational control of ribosomal proteinsB) Global controlsC) RNA specific controlsD) Allosteric modifications of ribosomesE) Energy depletion

Ans A

41) Which of the following is a synonymous codon with UCU?

A) AAUB) UCAC) GAUD) AAAE) CUG

Ans B

42) Protein synthesis in bacteria involves six functional centers. Which of the following is not one of those centers?

A) Decoding centerB) Aminase transfer centerC) Pepidyl transfer centerD) GTPase associated regionE) A site

Ans B

43) The peptide emerging from the exit tunnel first encounters a molecular factor called

A) Trigger factorB) Signal factorC) Linkage chaperone

D) P-siteE) Translation factor

Ans A

44) Eukaryotic initiation begins with the assembly of ________________.

A) Preinitiation complexB) Cap-binding complexC) Poly-binding complexD) 48S Initiation complexE) Translational initiation complex

Ans A

45) Which of the following compounds is referred to as the twenty first amino acid

A) SelenocysteineB) GlucolysineC) CysteineD) DehydroxyalinineE) D-Lysine

Ans A

46) During synthesis of secreted proteins; binding of the ribosome to the ER membrane is mediated by

A) The transloconB) SRP and SRP receptor proteinC) Signal peptidaseD) Cotranslational transferE) Posttranslational translocation

Ans B