BIO 302, Spring 2001
Review 2 - Microbial Genetics
Brief Answer Key
Answer 6 of the following 7 questions
The anti-HIV drug ddI has the following structure:
Explain its mode of action.
Expression of the tryptophan operon is controlled by
a repressor in a manner very similar to expression of the lactose operon.
The tryptophan operon also is regulated via a process known as attenuation.
Describe this process.
Compare and contrast transformation and generalized
A) For the following lac operon partial diploids, list
which genes will be expressed in the presence and absence of lactose. NOTE:
A (-) next to a gene indicates that a mutation exists in that gene that
precludes expression of that particular gene. Genes preceding the slash
exist on a plasmid. Genes following the slash exist on the chromosome.
B) Mutations in the lacI gene have been identified
that abolish the ability of the repressor (I) to bind to lactose (all other
functions of the repressor remain unchanged). Briefly describe the effects
of these mutations.
Eukaryotic mRNAs are monocistronic. Prokaryotic mRNAs,
however, may be polycistronic. Why?
Molecular biologists often comment that positive sense,
single stranded RNA viruses possess infectious RNA. What is meant by this
statement? Why is the same comment not true for negative sense, single
stranded RNA viruses?
The local chapter of Fish R Us has hired you as a consultant.
They are trying to produce large amounts of fish growth factor to dump
into Lake Norman and, hopefully, increase the size of the bass in the lake.
They have cloned the complete fish growth factor gene, including all its
regulatory regions, into a bacterial plasmid and transformed E. coli
with this plasmid. These bacteria, though, are not producing fish growth
factor. What are your recommendations to them? Explain why you made these