Chapter 10

Write a one-sentence definition of the term "genotype." Do the same for "phenotype." Does the phenotype of an organism automatically change when a change in genotype occurs? Why or why not? Can phenotype change without a change in genotype? In both cases, give examples to support your answer. (Section 10.1)

Explain why an Escherichia coli strain that is His \(^{-}\)is an auxotroph and one that is \(\mathrm{Lac}^{-}\)is not. (Hint: Think about how \(E\). coli metabolizes histidine and lactose and what each compound is used for.) (Section 10.1)

What are silent mutations? From your knowledge of the genetic code, why do you think most silent mutations affect the third position in a codon? (Section 10.2)

Give an example of one biological, one chemical, and one physical mutagen and describe the mechanism by which each causes a mutation. (Section 10.4)

What are heteroduplex regions of DNA and what process leads to their formation? (Section 10.5)

Explain why performing genetic selection is difficult when studying Archaea. Give examples of some selective agents that work well with Archaea. (Section 10.10)