You have an oligonucleotide probe that hybridizes to part of gene A from a eukaryotic cell. Indicate whether a cDNA library or a genomic DNA library will be more appropriate for use in the following applications
A. You want to study the promoter of gene A.
B. Gene A encodes a tRNA and you wish to isolate a piece of DNA containing the full-length sequence of the tRNA.
C. You discover that gene A is alternatively spliced and you want to see which predicted alternative splice products the cell actually produces.
D. You want to find both gene A and the genes located near gene A on the chromosome.
E. You want to express gene A in bacteria to produce lots of protein A.
A. Genomic library. (cDNAs are produced from mRNAs; therefore, the promoters will not be included in a cDNA library.)
B. Genomic library. (cDNAs are usually constructed by using an oligo dT primer; tRNAs do not have poly-A tails. If the cDNA library were made using random primers, it would be unlikely to contain the full-length version of the tRNA.)
C. cDNA library. (Because cDNAs are produced from mRNAs, isolating cDNAs would tell you which splice variants are produced in a cell.)
D. Genomic library. (A genomic DNA fragment can contain the genes next to your gene of interest; a cDNA will not.)
E. cDNA library. (Bacteria do not have the ability to remove introns, which may exist in DNA isolated from a genomic library.)
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