A 3-kb supercolled circular plasmid contains the restriction sites shown below. N and X represent Nhel and Xbal sites, r

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A 3 Kb Supercolled Circular Plasmid Contains The Restriction Sites Shown Below N And X Represent Nhel And Xbal Sites R 1 (54.09 KiB) Viewed 67 times

A 3 Kb Supercolled Circular Plasmid Contains The Restriction Sites Shown Below N And X Represent Nhel And Xbal Sites R 2 (66.87 KiB) Viewed 67 times

A 3-kb supercolled circular plasmid contains the restriction sites shown below. N and X represent Nhel and Xbal sites, respectively; A through F mark six points on the plasmid. A preparation of plasmid DNA was separately digested (cut) to completion with Xbal alone, Nhel alone, and a mixture of the two enzymes. The products were separated by agarose gel electrophoresis. A. Draw the predicted appearance of each digestion on the gel. -2 kb E D LL F N C A B 1 kb SHEN 000000 & A 312 216 1.5k 1Kb 750 bp 500 bp 2500p -Welle Lane M-A mixture of known markers from 250 bp to 10 kb (shown) Lane 1-Sample from the original plasmid DNA preparation (no digestion) (note: because uncut, supercoiled plasmid is very compact, it moves through the gel matrix easier than uncompacted DNA. You can expect it to run somewhere between 1.5-2000kb) Lane 2 Products of complete digestion with Xbal alone Lane 3 Products of complete digestion with Nhel alone Lane 4- Products of complete digestion with Xbal and hel B. Imagine this circular plasmid was actually a linear piece of DNA, with exactly the same genes and restriction enzyme sites. Would this change the number of bands you saw on the gel for each of the described digestion experiments in lanes 2, 3, and 4 above? If so, explain how many bands you would see for each and why. 2. Consider a cross of two haploid Neurospora strains, one with genotype A B C and the other with genotype a be. The three genes are linked a. Consider just alleles and b. Suppose that and b differ by one base pair: the B
2. Consider a cross of two haploid Neurospora strains, one with genotype ABC and the other with genotype a b c. The three genes are linked. a. Consider just alleles B and b. Suppose that B and b differ by one base pair: the B allele has an AT base pair and the b allele has a G:C base pair at the same position. If meiosis and tetrad formation occurs without heteroduplex formation in the B/b diploid, what possible tetrads can be expected? (write the possibilities as patterns of B's, for example: BBBBBbbb) b. With respect to the "B" gene, suppose some aberrant tetrads were formed. When examining the flanking A and C genes, the following spores were identified (with spores in the order shown). Answer the questions about the meiotic events leading to the formation of both of the asci shown belop. (hint: the A and Cgene patterns are what is affected by the different resolution pathways. The B gene pattern is what is affected by the repair or no repair of heterodyplexes) ABC ABC ABC ABC aBc abc abc abc L ii. The crossover happened between the A and C genes. Was it same plane resolution or opposite plane resolution? Explain your reasoning. il. Heteroduplex(es) was/were formed. List all the possible ways they could have been repaired, or if they were repaired at all, to get this spore pattern. Explain your reasoning. ABC ABC ABC ABC aBC aBC abc abc 1. The crossover happened between the A and C genes. Was it same plane resolution or opposite plane resolution? Explain your reasoning. Heteroduplex(es) was/were formed. List all the possible ways they could have been repaired, or if they were repaired at all, to get this spore pattern. Explain your reasoning.