CH. 18 STUDY GUIDE: Virus and Bacterial Genetics
KEY TERMS
VIRUSES
plasmids
capsid
transposons("jumping genes")
nucleic acid core
structural gene
lytic cycle
regulator gene
lysogenic cycle
operator
bacteriophage
operon
vectors
promoter
provirus
inducer
BACTERIA
repressor
bacterial chromosome
activator
transformation
repressible enzymes
transduction
inducible enzymes
conjugation
cAMP-CAP complex
prion
restriction enzymes
viriod
retrovirus
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WORD ROOTS
capsa - = a box (capsid: the protein shell that encloses the viral genome).
conjug - = together (conjugation: in bacteria, the transfer of DNA between two cells that are
temporarily joined)
lyto - = loosen (lytic cycle: a type of viral replication cycle resulting in the release of new phages
by death or lysis of the host cell).
- oid = like, form (nucleoid: a dense region of DNA in a prokaryotic cell)
- phage = to eat (bacteriophages: viruses that infect bacteria).
pro - = before (provirus: viral DNA that inserts into a host genome)
retro - = backward (retrovirus: an RNA virus that reproduces by transcribing its RNA into DNA
and then inserting the DNA into a cellular chromosome)
trans - = across (transformation: a phenomenon in which external DNA is assimilated by a cell).
virul - = poisonous (virulent virus: a virus that reproduces only a lytic cycle).
QUESTIONS
1. Using a diagram describe the lytic and lysogenic cycles of viral replication.
Use the following terms in your description: virulent, temperate, lysogenic
cells, lytic cycle, provirus and vegetative virus.
2. Describe the bacterial chromosome. How does it differ from a eukaryotic
chromosome?
3. Describe the nature of bacterial plasmids and discuss their role in
recombinant DNA studies.
4. Using a diagram describe the process of transduction by bacteriophages
and tell of the implications and uses of this process.
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5. Describe prokaryotic gene induction. Explain the role of inducer, operator,
promoter and repressor, the regulator gene and the structural genes.
6. Using a diagram, describe the function of a repressible operon and explain
how it differs from an inducible operon.
7. Using a diagram, describe how the cAMP-CAP complex facilitates
transcription.
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