MICR 271 Final Exam Questions and Answers Graded A+.

MICR 271 Final Exam Questions and
Answers Graded A+.
Replisome Speed - Answer eukaryotic slower - must displace nucleosomes, cell-dependent
regulation of replication



multiple initiation sites to compensate



Bacterial Replication Forks - Answer 1. Helicase unwinds DNA, lagging strand coated with
single stranded binding proteins, RNA primer synthesized by primase



2. DNA Pol III holoenzyme tethered to DNA by beta clamp, loaded by t-clamp loader



3. 1 Pol III core leading strand synthesis (continuous)



4. 2 Pol III cores lagging strand synthesis (okazaki fragments)



5. Pol I removes primer and fills with DNA, Ligase joins strands



Eukaryotic Replication Fork - Answer 1. Helicase (Mcm2-7) + proteins (GINSS, Cdc45, Mcm10)
activate unwound DNA, ssDNA bound by replication protein A



2. Helicase associates wtih primase (synthesizes RNA primer)



3. Pol ε does leading, Pol δ does lagging (loaded onto DNA by proliferating cell nuclear antigen,
carried to DNA by replication factor C)



4. shorter okazaki fragments generation, Pol δ removes RNA primer and fills with DNA, ligase
seals gap



Family A DNA Polymerases - Answer replication/repair



Family B DNA Polymerases - Answer DNA replication, 3'-5' exonuclease activity



Family C DNA Polymerases - Answer DNA replication

,Family D DNA Polymerases - Answer DNA replication



Family X DNA Polymerases - Answer DNA damage repair



Family Y DNA Polymerases - Answer translesion DNA repair



Translesion Repair - Answer insert bases opposite damaged nucleotides or repair dsDNA
breaks



Class I virus - Answer dsDNA genome



mRNA synthesis: transcription using host machinery, translatin mRNA --> proteins



genome replication: using host machinery



Class II virus - Answer ssDNA genome (+ or -)



mRNA synthesis: dsDNA transcribed into mRNA using host machinery



genome replication: dsDNA produced and replicated, strands separated



Class III virus - Answer dsRNA genome



mRNA synthesis: separated into ssRNA, + strand used as mRNA, translated into viral proteins



genome replication: + ssRNA = template to produce new dsRNA



Class IV virus - Answer + ssRNA genome



mRNA synthesis: + ssRNA used as mRNA, translated into proteins



genome replication: + ssRNA used to produce - ssRNA = template to produce new + ssRNA



Class V virus - Answer - ssRNA genome

, mRNA synthesis: -ssRNA template to make + ssRNA (mRNA) translated into proteins



genome replication: -ssRNA used to produce + ssRNA = template to produce new -ssRNA



Class VI viruses - Answer Retroviruses



ssDNA reverse transcribed from RNA genome, dsDNA made using DNA Pol



mRNA synthesis: dsDNA integrated into host genome --> mRNA --> protein



genome replication: + ssRNA --> ssDNA by viral reverse transcriptase --> dsDNA into host
genome by integrase --> +ssRNA to produce new genomes



Class VII viruses - Answer Reverse transcribing dsDNA genome



mRNA synthesis: dsDNA --> mRNA by viral RNA Pol --> proteins



genome replication: + ssRNA --> ssDNA by reverse transcriptase --> partially dsDNA genomes



T4 Phage - Answer dsDNA genome



1. linear dsDNA genome injected



2. bacterial RNA Pol makes "early" mRNA = template for transcription of DNA-dependent DNA
polymerase



3. Host DNA degraded, phage DNA starts replicating (incorporates hydroxymethylcytosine to
protect from degradation by restriction enzymes)



4. phage DNA replicated, remaining mRNA transcribed by modified host RNA Pol (promotes
phage gene expression)



5. phage structural component genes translated when phage DNA ready for packaging



6. ~150 phages assembled, cell lysed by holin and endolin