Biochemistry Chapter 19

Front 1

The Shine-Dalgarno sequence is a

Back 1

Prokaryotic mRNA sequence that binds 16S rRNA of the small ribosomal subunit

Front 2

The initiation phase of prokaryotic trasnaltion ends as the GTP molecule bound to ______ is hydrolysed to GDP and Pi

Back 2

IF-2

Front 3

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

Back 3

EF-Tu-GTP

Front 4

_____ is an enzymatic activity that hydrolyses the bond linking the completed polypeptide chain and the P sit tRNA

Back 4

Peptidyl transferase

Front 5

Prominent prokaryotic post-translational modifications include all of the following except

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

Back 5

Prenylation

Front 6

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

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

Back 6

Transcription

Front 7

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

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

Back 7

Lactose transferase

Front 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

Back 8

eEF-2

Front 9

In eukaryotic translation the 40S complex binds the 60S subunit to form the _______initiation complex.A) 80SB) 88SC) 90SD) 100SE) 108S

Back 9

80S

Front 10

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

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

Back 10

GTP

Front 11

Polypeptides containing signal peptides are called ________.

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

Back 11

Preproproteins

Front 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

Back 12

Glycosylation Reactions

Front 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

Back 13

Ribosomal polypeptide translocation factor

Front 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

Back 14

Large alterations in mRNA translation patterns

Front 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

Back 15

All of the above are correct

Front 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

Back 16

Most hnRNA is processed into mRNA

Front 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

Back 17

All of the above are correct

Front 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

Back 18

Both A and B are correct

Front 19

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

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

Back 19

Ferritin

Front 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

Back 20

Inhibits prokaryotic peptidyl transferase

Front 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

Back 21

Inhibits eukaryotic peptidyl transferase

Front 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

Back 22

Interferes with aminoacyl-tRNA binding to the 30S subunit

Front 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

Back 23

Inhibits prokaryotic peptide chain elongation

Front 24

Which of the following antibiotics would be most toxic for humans

A) TetracyclineB) ChloramphenicolC) StreptomcyinD) CycloheximideE) Erythromycin

Back 24

Cycloheximide

Front 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

Back 25

Both A and B are correct

Front 26

_________ is a translation factor that possesses a unique histidine residue that can bemodified to form dipthamide

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

Back 26

eEF-2

Front 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

Back 27

Both A and B are correct

Front 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

Back 28

All of the above are correct

Front 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

Back 29

1 and 3 minutes

Front 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 a-amino group on the carbonyl carbonof the P side amino acidD) Catalyses peptide bond formationE) All of the above are correct

Back 30

All of the above are correct

Front 31

Energy for ribosome function is provided by

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

Back 31

GTP

Front 32

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

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

Back 32

4

Front 33

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

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

Back 33

32

Front 34

Translation begins with

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

Back 34

Initiation

Front 35

Which of the following is a type of posttranslational modification?

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

Back 35

All of the above

Front 36

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

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

Back 36

4

Front 37

An amino acid coded for by a stop signal is

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

Back 37

Both A and D are correct

Front 38

In eukaryotes which of the following amino acids is often hydroxylated after proteinsynthesis?

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

Back 38

Proline

Front 39

Which of the following amino acids is sometimes carboxylated after protein synthesisin eukaryotes

A) GlutamateB) AspartateC) PhenylalanineD) LysineE) Arginine

Back 39

Glutamate

Front 40

Prokaryotes exclusively use which of the following translational controlmechanisms?

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

Back 40

Negative translational control of ribosomal proteins

Front 41

Which of the following is a synonymous codon with UCU?

A) AAUB) UCAC) GAUD) AAAE) CUG

Back 41

UCA

Front 42

Protein synthesis in bacteria involves six functional centers. Which of the followingis not one of those centers?

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

Back 42

Aminase transfer center

Front 43

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

A) Trigger factorB) Signal factorC) Linkage chaperoneD) P-siteE) Translation factor

Back 43

Trigger factor

Front 44

Eukaryotic initiation begins with the assembly of ________________.

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

Back 44

Preinitiation complex

Front 45

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

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

Back 45

Selenocysteine

Front 46

During synthesis of secreted proteins; binding of the ribosome to the ER membraneis mediated by

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

Back 46

SRP and SRP receptor protein