Pick the correct answer choice: (Problem 24) In yeast, you have sequenced a piec
ID: 262055 • Letter: P
Question
Pick the correct answer choice:
(Problem 24) In yeast, you have sequenced a piece of wild-type DNA and it clearly contains a gene, but you do not know what gene it is. Therefore, to investigate further, you would like to find out its mutant phenotype. How would you use the cloned wild-type gene to do so? Mutate the gene using a version of PCR that creates mutations in a gene sequence. Insert the mutant gene into the yeast, allowing the mutant gene to recombine and replace the normal gene. Now look for a mutant phenotype. Mutate the gene using a version of PCR that creates mutations in a gene sequence. Clone the mutant gene into bacteria and express the mutant protein using an in vitro method. Analyze the bacteria for a mutant phenotype. Using the wild-type gene, probe libraries of yeast DNA looking for clones that hybridize weakly to the wild-type gene. These are likely mutant copies of the gene. Isolate those yeast containing the putative mutant, grow them, and analyze for a mutant phenotype. Construct a recombinant expression vector containing the wild-type gene cloned into it and a selectable marker gene inserted into the wild-type gene. Transform yeast cells and grow under conditions that select for the marker gene. This procedure will knock out the gene of interest. Analyze for a mutant phenotype.Explanation / Answer
Ans 11: Whole genome shotgun approach would be use to sequence the genome of a newly discovered bacterial species.
Ans 13: Scaffold are composed of contigs and gaps. It is not a sequence of overlapping reads or not a collection of join together contigs. Scaffolds are also not a part of the apparatus used in the generating contigs. Therefore none of the options is correct.
Ans 15: When a segment of cloned DNA containing a protein encoding gene radioactively labelled and used in situ hybridization radioactiovity was observed over five regions on different chromosome. It may be due to the clone may contain DNA that hybridize to a small family of repetitive DNA adjacent to the gene being studied or within one of its introns; the clone may share homology with members of a small gene family therefore it hybridized all of them; there may be 4 pseudogenes that are descendants of the gene being studied
Therefore all of the options are correct.
Ans 34: Kanamycin resistant is a dominant phenotype. In plant 1, the Ti vector inserted the gene of interest once into the tobacco plant and in plant 2 the Ti vector inserted the gene of interest twice into the tobacco plant. For this reason, while plant 2 was backrossed with wild type 75% of the progeny showed Kanamycin resistance and 25 % showed sensitivity. On the other hand while plant 1 was backcrossed with wild type 50% progeny showed Kanamycin resistance and 50 % showed sensitivity.
Ans24: As we don't know the gene sequence it is not possible to mutant that specific gene by PCR; so we can eleminate option 1 and 2. Again to clone a gene we need to know the sequnce of that specific gene therefore construction of a recombinant expression vector containg the wild type gene is also not feasable.
Therefore option 3 "Using the wild-type gene, probe libraries of yeast DNA looking for clones that hybridize weakly to the wild-type gene. These are likely mutant copies of the gene. Isolate those yeast containing the putative mutant, grow them, and analyze for a mutant phenotype" is correct..