Download BIO208

BIO208
Bacterial Genetics Worksheet
1
1. Using standard bacterial genetic notation, write the genotypes of bacterial strains that have the
following characteristics:
a. unable to metabolize the sugar lactose (lac)
b. able to make the amino acid leucine (leu)
c. resistant to the antibiotic streptomycin (str)
d. sensitive to the antibiotic puromycin (pur)
2. Is strain "a" in question #1 prototroph or an auxotroph? Strain "b"? (Assume the strains are wildtype
for all genes but the one in question).
3. Describe 5 steps involved in the lytic life cycle of bacteriophages.
4. Fill in
Transformation
Transduction
Conjugation
_______________a. naked DNA is involved
_______________b. faulty head stuffing may occur
_______________c. involves exconjugants
_______________d. adsorption and injection of genetic material
_______________e. competent cells required
_______________f. an F plasmid encodes attachment proteins
_______________g. used to construct the E. coli minute map
_______________h. a pilus is produced
_______________i. lytic cycle entered in response to stress
_______________j. may be specialized or general
_______________k. requires cell to cell contact
_______________l. mediated by a virus
_______________m. known as parasexual mating
_______________n. requires competent cells
_______________o. involves a phage
5. Fill in using this word bank
homologous recombination
F Factor(plasmid)
generalized
interrupted mating
extrachromosomally (episomally)
Hfr bacterial strain
specialized
adsorption
F+ cell
F minus (F-)
lysogeny
a. the reciprocal exchange of DNA between two DNA fragments of identical (or at least close to
identical) sequences is called __________________________________
b. A plasmid can be maintained ______________ or integrate into bacterial chromosome.
c. In ______________ transduction, all bacterial DNA has equal probability of being packaged.
d. In ____________, phage genome integrates into bacterial genome creating a prophage.
e. In _______________transduction, the phage excises, and may also clip bacterial genes
f. The ________________ contains ~100,000 base pairs and contains 19 genes that encode for
proteins involved in pili synthesis and other functions
g. The F factor occasionally integrates randomly into the E. coli chromosome creating a(n)
___________________
h. In normal conjugation, recipient (female) cells remain __________
i. The __________________ technique involves conjugation and plating cells at different times
j. After a phage engages in _____________, it will inject genetic material into bacterium
BIO208
Bacterial Genetics Worksheet
2
6. What is the difference between:
a. A bacterial colony and a lawn
b. The log phase and the stationary phase of bacterial growth
c. Minimal media and complete media
d. A conditional mutant and a nutritional mutant
e. Binary fission and parasexual mating
f. A prototroph and an auxotroph
g. A plasmid and a chromosome
h. Generalized and specialized transduction
i. A phage and a bacterium
j. An F+, an Hfr, and an F- cell
k. A donor and recipient cell
l. A U tube and a blender
m. Size of F factor and size of bacterial genome
n. Lytic and lysogenic cycle
o. A virulent and a temperate phage
p. Prophage and phage
q. Phage adsorption and phage packaging
7. What is the difference between
a. operon inducer and repressor
b. betagalactosidase and Z structural gene
c. promoter and operator
d.
O and Oc
e. I and If. lactose and glucose
g.
negative and positive operon regulation
h. polycistronic and monocistronic (as in humans) mRNA
i.
constitutive and superrepressor mutants
8. Operons are found in (circle one)
a. Prokaryotes
b. Eukaryotes
9. Fill in using the following choices
lactose
repressor protein
operator
lac Z
promoter
beta galactosidase
a. _____________________________ DNA that binds repressor to prevent transcription
b. _____________________________ DNA that binds RNA polymerase
c. _________________________ binds repressor to allow transcription
d. _____________________________ a structural gene of the operon
e. _____________________________ is bound by lactose
f. _____________________________ a trans acting protein that represses the operon
g. _____________________________ encoded by the I gene
h. __________undergoes a conformational (shape) change which prevents binding to the operator
i. _____________________________ gene that is actively transcribed when derepressed
j. _____________________________ enzyme that cleaves lactose into glucose and galactose
k. _____________________________ 3 DNA elements of the lac operon
l. _____________________________ 2 proteins associated with the lac operon
m. _____________________________ 1 sugar associated with the lac operon
BIO208
Bacterial Genetics Worksheet
3
10. A normal bacterial cell is grown in lactose (sugar). Is the lactose operon
a. off (repressed)?
b. on (induced)
11. A bacterial cell has a lactose operon but the promoter is defective (mutated). All else is normal. The
bacteria is transformed with a plasmid that contains a wildtype (non-mutated) promoter, amp resistance
gene, and origin of replication. Can the cell utilize lactose when grown in the presence of the sugar?
Why or why not?
12. Match the plasmid feature to the gene
_____ allows cell to deactivate ampicillin
A. ara C
_____ allows plasmid to replicate autonomously
B. bla gene
(independent of bacterium)
C. ori
_____ allows cells to manufacture GFP (protein)
D. GFP gene
_____ regulates the expression of GFP gene
E. multiple cloning site
_____ enables genes to be ligated into plasmid
_____ known as a reporter gene
_____ also called ampR
_____ recognized by various restriction enzymes
_____ a foreign gene not normally found in bacteria
_____ enables jellyfish and other marine organisms to glow
13. Why is it useful for a cell to have operons?