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Exam 3 Practise questions
Terms in this set (21)
Which of the following is a characteristic of bacteria?
b)bidirectional exchange of genetic material
c) genome size that is larger than that found in eukaryotes
d) none of the above
- bacteria don't make gametes
- there is only unidirectional exchange in bacteria
-bacteria is obviously smaller in chromosome size than eukaryotes
The distinction between an episome and a non-episomal plasmid involve what?
a) the ability to integrate into a host genome
b) presence/absence of an origin
c) circularity vs linearity
d) DNase sensitivity
- an episome is able to integrate into a host plasmid and a non-episome is not
(remember that plasmids are molecules that contain an origin of replication)
A cell in which an F factor is integrated within the chromosome is called:
- F+ cells contain a nonintegrated F factor
-F- cells do not contain an F factor
-there is no such thing as F= cells
- F' cells have an entire f factor that is non integrated along with chromosomal DNA
Which of the following are involved in conjugation?
a) proteins that bind DNA to the cell wall surface of the recipient cell
b) F factors
d) a virus
e) a conjugation channel
-a is transformation
- d is not involved
The mating that is most likely to product 2 F+ cells is:
a) F+ x F-
b) Hfr x F-
c) Hfr x F+
d) F' x F-
e) F- x F-
What factors may cause fixation?
natural selection or genetic drift
How to tell between natural selection and genetic drift?
if natural selection is involved, then all populations should be fixed for the same allele, but if different alleles are fixed than the driving force is genetic drift
How to tell when the driving force is inbreeding?
decline in the frequency of heterozygotes and an increase in the frequency of homozygotes
How to tell when the driving force is migration?
no change in allele frequencies or minor changes
Which of the following can describe an episome that contains the genes required for conjugation, as well as a few genes from the E. coli chromsome?
a) F- factor
b) F= factor
c) F+ factor
d) F' factor
e) F factor
The origin of replication that initiates the rolling circle replication of an F factor is located:
a) at the 5' end of the F factor
b) at the 3' end of the F factor
c) within the host chromosome (not within the F factor)
d) within the F factor
During transduction, the longer two cells stay together, the more DNA will be transferred.
true or false?
transduction doesn't require two cells to come together
conjugation does though, so this would be true for conjugation
Which of the following matings most commonly produces one Hfr cell and one F- cell?
a) Hfr x Hfr
b) Hfr x F'
c) Hfr x F-
d) Hfr x F+
e) F+ x F'
suppose that there are three mutations in E. coli, q-, m-, and x-. Each of the mutations is recessive to the wild type allele (q+,m+, and x+). Tests are completed in which DNA from wild type strains is partially fragmented , and this DNA is then used to transform mutant strains. In some cases, q+,m-, and x+ transformants are produced, and in some cases q-, m+, x+ transformants are produced. There are no other transformants produced ( but only a small number were tested). What can you conclude about the order of the genes on the E.coli chromosome?
genes that are closer together will be involved in trasformation together more often, so based on the information we have, this means that x is located between m and q
Which of the following allow two bacterial cells physically contact one another?
a) transformation pili
c) conjugation channels
d) all of the above
Which of the following insert into host chromosomes at random locations?
a) T4 genomes
b) lambda genomes
c) F factors
d) Hfr factors
e) none of the above
f) all of the above
g) b & c only
Incorrect excision produces which of the following:
a) F factors
b)lambda deficient viruses
c) F' factors
d) Hfr cells
e) all of the above
f) none of the above
g) b & c only
an operon involved in the breakdown of a disaccharide in E. coli is transcribed at a high rate when a regulatory molecule binds to the promoter of the operon. Is this an example of a negative or positive control?
this regulatory molecule is composed of a regulator gene product and a disaccharide. When the disaccharide is in low concentration, the regulatory molecule dissociates from the promoter. Is this a repressible or inducible operon?
a positive control; inducible
When the transcription of a prokaryotic gene is inhibited in response to a substance in the environment, the gene is under what type of control?
co-repressors are always invovled in what type of gene regulation systems?
when the transcription of a prokaryotic gene is inhibited when regulatory molecules bind to the promoter, it is called:
a) inducible control
b) repressible control
c) positive control
d) negative control
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