Chapter 5 Exploring Genes and Genomes 7 11 Briefly outline how a cDNA library is made. Ans:Reverse transcriptase is used to convert mRNA molecules into DNA,and the RNA is then digested away by alkali.Terminal transferase is used to add several residues to the end of the fragment,such as G.Then,a complementary primer,such as polyC,can be used to synthesize the opposite strand.Linkers can be added so the fragment can be inserted into a vector.and then into a host.such as bacteria. Section:5.3 and Figure 5.17 12 Why are foreign genes often inserted with a different promoter,such as the metallothionein gene promoter? Ans:Promoters are selected that are easy to control,and can be turned on or off as desired. Thus,metallothionein,which is induced by the presence of heavy metals,can be mediated by altering metals concentrations. Section:5.4 13 How is gene disruption used to determine the function of a gene? Ans:If a gene is completely disrupted (also called gene knockout),a functioning protein is not made.By examining the knockout organism,clues to the protein's function can be made by observation and testing. Section:5.4 14 How is a gene gun used? Ans:DNA is coated onto tungsten pellets,and the microprojectiles are shot into the tissue at very high velocity. Section:5.4 15 What advantage can be gained by splicing together portions of two different genes? Ans:This technique allows the creation of novel bifunctional genes.Distinct functional domains are paired and aligned into one gene,often resulting in proteins with unique characteristics and activities. Section:5.4Chapter 5 Exploring Genes and Genomes 7 11 Briefly outline how a cDNA library is made. Ans: Reverse transcriptase is used to convert mRNA molecules into DNA, and the RNA is then digested away by alkali. Terminal transferase is used to add several residues to the end of the fragment, such as G. Then, a complementary primer, such as polyC, can be used to synthesize the opposite strand. Linkers can be added so the fragment can be inserted into a vector, and then into a host, such as bacteria. Section: 5.3 and Figure 5.17 12 Why are foreign genes often inserted with a different promoter, such as the metallothionein gene promoter? Ans: Promoters are selected that are easy to control, and can be turned on or off as desired. Thus, metallothionein, which is induced by the presence of heavy metals, can be mediated by altering metals concentrations. Section: 5.4 13 How is gene disruption used to determine the function of a gene? Ans: If a gene is completely disrupted (also called gene knockout), a functioning protein is not made. By examining the knockout organism, clues to the protein’s function can be made by observation and testing. Section: 5.4 14 How is a gene gun used? Ans: DNA is coated onto tungsten pellets, and the microprojectiles are shot into the tissue at very high velocity. Section: 5.4 15 What advantage can be gained by splicing together portions of two different genes? Ans: This technique allows the creation of novel bifunctional genes. Distinct functional domains are paired and aligned into one gene, often resulting in proteins with unique characteristics and activities. Section: 5.4