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Unformatted text preview: 1) Suppose you were to run a PCR on normal DNA using dNTP ’ s labeled with 15 N. How would the DNA separate on a CsCl gradient after one cycle? How would the DNA separate on a CsCl gradient after two cycles? 2) Place the following activites under the appropriate polymerase: 3 ’->5 ’ DNA polymerase activity (DNA synthesis) 5 ’->3 ’ exonuclase activity 5 ’->3 ’ DNA polymerase activity (DNA synthesis) 3 ’->5 ’ exonuclease acticity DNA Polymearse I DNA Polymerase III 3) Match the protein with its function Primase Sliding clamp/B-subunit Helicase SSB Topoisomerase Tau Initiator * Prevents polymerase from dissociating with the DNA, a ring structure * Makes an RNA primer, is most often associated with lagging strand * Recognizes speciFc origin sequence, ATPase * Protein that holds the polymerase subunits together * Breakage and joining of DNA strands so strands can rotate freely around eachother and relieve tension * Unwinds DNA using ATP * Cooperatively stabilizes single stranded DNA, found on the lagging strand Practice problems for Midterm 2: *DNA replication*DNA repair*Cloning* 4) You have a plasmid which codes for ampicillian resistance and the alpha fragment of B-gal. The alpha-fragment has a BamHI site in the middle of its sequence. You want to clone a gene (which luckily is Fanked by BamHI sites) into the plasmid. You cut both the gene and the plasmid with BamHI, purify and ligate them together. You then transform your recombinant DNA into e.coli (a strain that expresses the beta subunit) and streak them on four different plates: 1)Nutrient + ampicillian 2)Nutrient + X-gal 3)Nutrient + Amp + X-gal 4)Nutrient alone a) What color colonies would you expect to see on plate #1? Do your bacteria contain a) What color colonies would you expect to see on plate #1?...
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- Fall '09
- DNA, BamHI, *DNA replication*DNA repair*Cloning*