BCHM Quiz 4

1. 1Allolactose has an important role in regulation of the lac operon because:

   1. AIt specifically directs lac repressor to the O3 operator
   2. BIt is the most abundant form of sugar metabolized by galactosidase
   3. CIt binds to an allosteric site in the repressor protein resulting in reduced affinity for the operator sites
   4. DIt bind to the lac repressor and activates its binding capability
   5. EIt binds to the CRP protein and causes induction of the lac gene
2. 2Allolactose is

   1. AAn effector
   2. BAn inducer
   3. CAn effector and a repressor
   4. DAn effector and an inducer
   5. EA repressor
3. 3Which of the following statements on the TATA binding protein is not true

   1. ATBP recognizes an AT rich sequence, known as the TATA box
   2. BTBP bends DNA by opening up the major groove
   3. CTBP is used by all three classes of eukaryotic RNA polymerase
   4. DTBP is used for transcription initiation of all genes, even when a TATA box is not present in the core promoter
   5. ETBP is recruited to near position -3- of the promoter through proteins known as TBP-associated factors (TAFs)
4. 4Which of the following characteristics is different between DNA-dependent DNA synthesis and DNA-dependent RNA synthesis?

   1. ASynthesis requires a template
   2. BSynthesis is catalyzed in the 5’ to 3’ direction
   3. CSynthesis requires a polymerase
   4. DInitiation of synthesis requires a primer
   5. EInitiation involves the recognition of a specific DNA sequence
5. 5DNAse 1 is used in footprinting to:

   1. ABind to the DNA to protect regions bound by the DNA binding protein
   2. BCleave the labelled end of the DNa target so that it does not cause background noise when the autoradiogram of the footprint is generated
   3. CCleave at specific sites along the DNa sequence to identify the underlying response element
   4. DCleave all of the target DNA
   5. ECleave essentially every DNA target molecule at a frequency of once per DNa molecule in regions unprotected by the DNa binding protein
6. 6An exoribonuclease is

   1. AAn enzyme that degrades RNA by cleaving the central portion of the molecule
   2. BAn RNase that functions in the nucleus
   3. CA nucleotide-transport protein
   4. DA noncoding RNA complexed with protein
   5. EAn enzyme that degrades RNA from the ends inward
7. 7You create this merodiploid bacterium (X = loss of function mutation) and culture it in the absence of lactose. What gene(s) will be expressed?

   

   1. ALacZ, LacY, and LacA
   2. BLacZ and LacA
   3. CLacY and LacA
   4. DLacZ
   5. ENone of the genes will be expressed
8. 8How does cAMP affect the expression of the lac operon?

   1. AcAMP binds to the CRP, increasing its affinity for a DNA site near the promoter
   2. BcAMP binds to the Lac repressor, decreasing its affinity for a DNA site near the promoter
   3. CcAMP binds to the Lac repressor, increasing its affinity for a DNA site near the promoter
   4. DcAMP is a substrate for RNA polymerase
   5. EcAMP binds to the CRP, decreasing its affinity for a DNA site near the promoter
9. 9Electrophoretic mobility shift assays are important for

   1. ADetermining whether transcription factors bind to DNA as homodimers
   2. BEstablishing which regions of a promoter are important for promoting transcription
   3. CAll the answers are correct
   4. DIdentifying specific transcription factors that bind to DNA elements
   5. EIdentifying DNA elements that bind to specific transcription factors
10. 10Galactosidase permease is important because without it

    1. AAllolactose would not formed
    2. BAll the answers are correct
    3. CCells would starve in the absence of glucose
    4. DThe cell membrane would be impervious of lactose
    5. ECells would not be able to metabolize lactose

11. 11Which of the following is true of transition mutations

    1. AA mutation in the first position of a codon is usually silent
    2. BThey involve the insertion of a single nucleotide
    3. CA mutation in the third position of a codon usually results in a missense mutation
    4. DThey involve a mutation outside the coding sequence of a gene
    5. EThey involve the replacement of a purine by a purine
12. 12The expression of the Lac operon in an E. coli cell missing the gene that encodes for the lac repressor will

    1. AIncrease when lactose is present
    2. BDecrease when lactose is present
    3. CIncrease when glucose is present
    4. DDecrease when glucose is present
    5. EAlways be reduced, independent of the sugars present
13. 13Which of the following is not true of the kinetic proofreading reaction of the bacterial RNA polymerase

    1. ArNTP is the product
    2. BIt occurs when the enzyme stalls after incorporating a mismatched base
    3. CThe type of reaction is pyrophosphorolysis
    4. DWater is the nucleophile
    5. EPyrophosphate is a reactant
14. 14Which of the following statements regarding transcription only applies to prokaryotes and not to eukaryotes?

    1. AA region of the promoter about 30 nucleotides upstream of +1 contains AT-rich base pairs
    2. BThe RNA start site is designated +1
    3. CInitiation of transcription is enhanced by the presence of a Kozak sequence
    4. DImportant sequence elements are frequently found downstream of +1
    5. EA region of the promoter about 10 nucleotides upstream of +1 contains AT-rich base pairs
15. 15Which of the following characteristics of transcription is similar to that for DNA replication?

    1. ADNA strands are duplicated
    2. BOnly certain genes serve as templates at any given time
    3. CJust one of the two strands of a DNA segment serves as a template
    4. DNascent strands dissociate from the template
    5. EThe process has distinct initiation, elongation, and termination phases
16. 16DNAse I is used in footprinting to:

    1. ACleave at specific sites along the DNA sequence to identify the underlying response element
    2. BCleave essentially every DNA target molecule at a frequency of once per DNA molecule in regions unprotected by the DNA binding protein
    3. CCleave all of the target DNA
    4. DBind to DNA to protect regions bound by the DNA binding protein
    5. ECleave the labelled end of the DNA target so that it does not cause background noise when the autoradiogram of the footprint is generated
17. 17Which of the following sequences is NOT generally found in the core promoter of RNA polymerase II?

    1. ABRE
    2. BDPE
    3. Cenhancer
    4. DInr
    5. ETATA
18. 18A corepressor is distinct from a repressor in that:

    1. AOnly co-repressors recruit HDAC activity
    2. BA repressor blocks the activity of one gene and the co-repressor blocks the activity of an adjacent gene
    3. CA repressor has DNA binding activity whereas a corepressor does not and relies on other transcription factors for its activity
    4. DA co-repressor has DNA binding activity whereas a repressor does not and relies on other transcription factors for its activity
    5. EOnly co-repressors bind the TATA box
19. 19The majority of transcription in eukaryotic cells is accounted for by

    1. ASynthesis of tRNA by RNA Pol III
    2. BSynthesis of mRNA by RNA Pol II
    3. CSynthesis of rRNA by RNA Pol III
    4. DSynthesis of rRNA by RNA Pol I
    5. ESynthesis of tRNA by RNA Pol I
20. 20The nucleophile of the peptidyl transferase reaction is the:

    1. Aα-amino group of the aminoacyl-tRNA in the A site.
    2. Bcarbonyl carbon of the ester bond linking the peptide chain to the tRNA in the P site.
    3. Cα-amino group of the peptidyl-tRNA in the P site.
    4. Dcarbonyl carbon of the ester bond linking the amino acid to the tRNA in the A site.
21. 21The Shine–Dalgarno mRNA sequence is specifically recognized by

    1. AThe 18S rRNA of the 40S subunit
    2. Bprotein S5 of the 30S subunit
    3. CN-formylmethionyl-tRNAfMet
    4. Dthe 16S rRNA of the 50S subunit
    5. Ethe 16S rRNA of the 30S subunit
22. 22Which of the following does not reflect the action of an effector molecule on the transcription of a gene?

    1. AAn effector binds to a repressor to decrease the level of transcription
    2. BAn effector binds to a repressor to increase the level of transcription
    3. CAn effector binds to a polymerase to increase the level of transcription
    4. DAn effector binds to an activator to increase the level of transcription
    5. EAn effector binds to an activator to decrease the level of transcription
23. 23Indicate which of the following RNA products is most likely to be synthesized by RNA polymerase III in eukaryotic cells.

    1. AmicroRNA
    2. B25S rRNA
    3. CtRNA
    4. DmRNA
    5. E18S rRNA
24. 24Which of the following is NOT true of the reaction catalyzed by RNA polymerases?

    1. AU residues are incorporated into the RNA to pair with T residues of the template
    2. BPrecise hydrogen bonding between the incoming ribonucleotide and the template strand must occur before reaction can proceed
    3. CThe 3'-hydroxyl group of the growing RNA strand is a nucleophile
    4. DThe reaction is magnesium ion-dependent
    5. ETemplate DNA is copied from the 3' to the 5' direction
25. 25Allolactose has an important role in regulation of the lac operon because:

    1. AIt specifically directs lac repressor binding to the O3 operator
    2. BIt binds to the lac repressor and activates its binding capability
    3. CIt is the most abundant form of sugar metabolized by galactosidase
    4. DIt binds to the CRP protein and causes induction of the lac gene
    5. EIt binds to an allosteric site in the lac repressor protein resulting in reduced affinity for the operator sites
26. 26Which of the following is not a component of the bacrterial RNA polymerase holoenzyme?

    1. ASubunit beta
    2. BSubunit alpha
    3. Csigma factor
    4. Dsubunit omega
    5. ENone of the above
27. 27The sequence of the messenger RNA molecule (primary transcript) synthesized from a DNA molecule with a template strand having the sequence 5'- ATGCTACCGTTA-3' is:

    1. A5’-UACGAUGGCAAU-3’
    2. B5’-TAACGGTAGCAT-3’
    3. C5’-TACGATGGCAAT-3’
    4. D5’-UAACGGUAGCAU-3’
    5. E5’-UAAGGCUCCAUG-3’
28. 28Which of the following is NOT true of the formation of a bacterial translation initiation complex?

    1. AThe 30S ribosome associates with the mRNA before the 50S ribosome.
    2. BN-formylmethionyl-tRNAf^Met binds in the P site.
    3. CIF-3 binding to GTP is required for the charged tRNA to associate with the first mRNA codon.
    4. DIF-1, IF-2, and IF-3 dissociate upon the 50S subunit binding.
29. 29A single nucleotide insertion mutation holds the potential to alter how many amino acids in the resultant protein?

    1. AOne amino acid
    2. BTwo amino acids
    3. CThree amino acids
    4. DMore than one amino acid
    5. ENo amino acids, the mutation would be silent
30. 30Which of the following proteins is NOT associated with the C-terminal domain of RNA polymerase II?

    1. Acap binding complex
    2. BRNA-editing terminal uridylyl-transferase
    3. Cguanylyltransferase
    4. Dpolyadenylation factors
31. 31While on Mars you identify a new type of life that does not use the universal genetic code of all life on earth. Proteins in this life form also include a new amino acid, Gaeline, which is encoded by the codons UCU, UCC, UCA and UCG. Based on Crick’s rules of the wobble hypothesis, what is the minimum number of tRNAs needed to translate all of these codons:

    1. A1
    2. B2
    3. C3
    4. D4
    5. E5
32. 32Tom and Jerry are monomeric transcription factors that can either form homodimers with themselves or heterodimers with each other. The DNA binding sequences for each monomer are shown in the figure. Which of the following sequences show the most likely binding sites for dimers A, B and C, respectively

    

    1. A
    2. B
    3. C
    4. D
    5. E
33. 33For the transcript shown in the diagram, which primer pair will allow for the qPCR amplification of a segment of cDNA, but not contaminating genomic DNA

    

    1. A1 & 2
    2. B1 & 3
    3. C1 & 4
    4. D2 & 3
    5. E3 & 4
34. 34You wish to perform qPCR for a splice variant that is close to the 5’ end of your mRNA of interest. This would be best accomplished by

    1. APerforming your reverse transcription reaction using Oligo dT primers
    2. BPerforming your PCR amplification using random hexamers
    3. CGenerating cDNA exclusively from the products of RNA Pol I
    4. DPerforming your reverse transcription reaction using random hexamers
    5. EPerforming your PCR amplification using Oligo dT primers

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Quiz on BCHM Quiz 4, created by joshua freedman on 25/11/2019.

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