Chapter 19 Solutions Manual Study Guide Rated A+

14. Briefly explain in situ hybridization, giving some applications of this technique. {Ans: Solution: In situ hybridization involves hybridization of radiolabeled or fluorescently labeled DNA or RNA probes to DNA or RNA molecules that are still in the cell. This technique can be used to visualize the expression of specific mRNAs in different cells and tissues and the location of genes on metaphase or polytene chromosomes.}36. A protein has the following amino acid sequence: Met-Tyr-Asn-Val-Arg-Val-Tyr-Lys-Ala-Lys-Trp-Leu-Ile-His-Thr-Pro You wish to make a set of probes to screen a cDNA library for the sequence that encodes this protein. Your probes should be at least 18 nucleotides in length. a. Which amino acids in the protein should be used to construct the probes so that the least degeneracy results? (Consult the genetic code in Figure 15.10.) b. How many different probes must be synthesized to be certain that you will find the correct cDNA sequence that specifies the protein? {Ans: a. Solution: A probe of 18 nucleotides must be based on six amino acids. The six amino acid stretch with the least degeneracy is Val-Tyr-Lys-Ala-Lys-Trp. This sequence avoids the amino acids arg and leu, which have six codons each. b. Solution: Val