QUESTION 1 How does proofreading increase the accuracy of ge

QUESTION 1 How does proofreading increase the accuracy of genome replication? a. the 5 to 3\' exonuclease activity of the DNA polymerase removes a nucleotide that has been incorrectly added to the end of the nucleotides being synthesized b. when the 3 terminal nucleotide is not base paired to the template it is removed by the exonuclease activity of the DNA polymerase c. the DNA polymerase discriminates against the incorrect nucleotide when these first become bound to the enzyme O d. proofreading increases the error rate in replication QUESTION 2 What methods were used to identify replication origin binding proteins in the Bell and Stillman paper? a. density gradient velocity) sedimentation, SDS PAGE, protein sequencing b. density gradient velocity) sedimentation, DNA footprinting, recombinant DNA expression O c. affinity chromatography, SDS-PAGE, DNA sequencing d. affinity chromatography, density gradient (velocity) sedimentation and DNA footprinting QUESTION 3 What feature makes the origin recognition complex unique among DNA binding proteins? a. ORC binds in the minor groove of the ACS b. ORC requires ATP for specific DNA binding C. ORC has quaternary structure d ORC slides along the DNA in the 3 to 5 direction

Solution

Please find the answers and explanations below:

Answer 1: Choice A (the fidelity of DNA replication is highly dependent upon proofreading activity of 5\' to 3\' of DNA polymerase which causes deletion of faulty nucleotide and insertion of correct nucleotide. This proof-reading capacity is found only in DNA polymerases of eukaryotes which makes the DNA replication process highly accurate)

Answer 2: Choice D (the classical research paper by Bell and Stillman identified the replication origin binding sites in Saccharomycyes by affinity chromatography, subsequent SDS-PAGE and DNA footprinting experiments)

Answer 3: Choice B (the origin of replication site of the eukaryotes contains some consensus sequences which are pre-requisite for binding of DNA binding proteins which can open up the DNA helix for onset of replication. These enzymes are ATP dependent.)

Answer 5: Choice B (DNA polymerase I and flap polymerase comprise of 5\' to 3\' polymerase and exonuclease activity which are exploited to remove RNA primers in PCR reactions. The same polymerase is utilized for strand amplicfication in eukaryotic DNA replication)