BioL 3001 Final Exam 2 Questions All
Solved Correctly 2026-2027 Edition.
Regulation of Gene Expression - Answer Promoter: site where RNA polymerase can bind to
DNA and begin transcription.
Operator: on/off switch
Genes are coordinately controlled
Operon: the operator, the promoter, and the genes they control
E. Coli Mutation Rate - Answer The probability of a spontaneous mutation occurring in a given
E. coli gene averages only about one in ten million (1x10^-7) per cell division. But among the
2x10^10 new E. coli cells that arise each day in a person's intestine, there will be approximately
(2x10^10) x (1x10^-7) = 2,000 bacteria that have a mutation in that gene. The total number of
mutations when all 4,300 E. coli genes are considered is about 4,300 x 2,000 = 9 million per day
per human host.
The key point is that new mutations, though rare, can increase genetic diversity quickly in
species with short generation times and large populations. This diversity, in turn, can lead to
rapid evolution: individuals that are genetically better equipped for their environment tend to
survive and reproduce more prolifically than less fit individuals.
Lederberg and Tatum (1945) experiments in bacteria that could not make arginine or
tryptophan but exchanged genetic information and recovered functions; bacterial
transformation - Answer Sexual reproduction (conjugation) between bacteria resulting in
transformation and the ability to now produce colonies. Shows that there is genetic exchange
between bacteria
2 E. coli mutants:
One can't synthesize tryptophan [can make argenine]
One can't synthesize argenine [can make tryptophan]
Exchange genetic information -- Bacterial Transformation: naturally exchange DNA
R or resistance plasmids - Answer "Resistance genes"
Carry the genes to code for enzymes that specifically destroy or otherwise hinder the
effectiveness of certain antibiotics, such as tetracycline or ampicillin.
Exposing a bacterial population to a specific antibiotic, whether in a laboratory culture or within
a host organism, will kill antibiotic-sensitive bacteria but not those that happen to have r
plasmids with genes that counter the antibiotic. Under these circumstances, we could predict
that natural selection would cause the fraction of the bacterial population carrying genes for
antibiotic resistance to increase, and that is exactly what happens.
F plasmid and bacterial conjugation through pilus - Answer Conjugation: DNA is transferred
between two prokaryotic cells (usually of the same species) that are temporarily joined.
, In bacteria, the DNA transfer is always one-way: one cell donates the DNA, and the other
receives it.
In E. coli, a pilus of the donor cell attaches to the recipient. The pilus then retracts, pulling the
two E. coli cells together , much like a grappling hook. The next step is thought to be the
formation of a temporary "mating bridge" between the two cells, through which the donor may
transfer the recipient.
F Factor: a particular piece of DNA that gives the ability to form pili and donate DNA during
conjugation. The F factor of E. coli consists of about 25 genes, most required for the production
of pili.
The F factor can exist either as a plasmid or as a segment of DNA within the bacterial
chromosome.
F Plasmid: the F factor in its plasmid form.
Cells containing the F plasmid, designated F+ cells, function as DNA donors during conjugation.
Cells lacking the F factor, designated F-, function as DNA recipients during conjugation. The F+
condition is transferrable in the sense that an F+ cell converts an F- cell to F+ if a copy of the
entire F+ plasmid is transferred.
Conjugation: DNA is transferred between two prokaryotic cells (usually of the same species)
that are temporarily joined.
In bacteria, the DNA transfer is always one-way: one cell donates the DNA, and the other
receives it.
In E. coli, a pilus of the donor cell attaches to the recipient. The pilus then retracts, pulling the
two E. coli cells together , much like a grappling hook. The next step is thought to be the
formation of a temporary "mating bridge" between the two cells, through which the donor may
transfer the recipient.
F Factor: a particular piece of DNA that gives the ability to form pili and donate DNA during
conjugation
Wollman and Jacob (1957) mapping the sequence of bacterial genes with interrupted
conjugation - Answer Used interrupted mating technique: the chromosome of Hfr bacteria
were transferred linearly -> gene order and distance can be predicted b/c specific genes were
transferred/recombined sooner than others.
BUT order of genes transferred varied between Hfr strains -> origin of transfer is diff per Hrf
strain
Jacob and Monod (1961) bacterial operon - Answer Used interrupted mating technique and
identified clusters of related genes with adjacent promoter region and switch segment, the
operator.
Named this the bacterial operon.
Operator is controlled by repressor protein made by regulator gene (located elsewhere).
Solved Correctly 2026-2027 Edition.
Regulation of Gene Expression - Answer Promoter: site where RNA polymerase can bind to
DNA and begin transcription.
Operator: on/off switch
Genes are coordinately controlled
Operon: the operator, the promoter, and the genes they control
E. Coli Mutation Rate - Answer The probability of a spontaneous mutation occurring in a given
E. coli gene averages only about one in ten million (1x10^-7) per cell division. But among the
2x10^10 new E. coli cells that arise each day in a person's intestine, there will be approximately
(2x10^10) x (1x10^-7) = 2,000 bacteria that have a mutation in that gene. The total number of
mutations when all 4,300 E. coli genes are considered is about 4,300 x 2,000 = 9 million per day
per human host.
The key point is that new mutations, though rare, can increase genetic diversity quickly in
species with short generation times and large populations. This diversity, in turn, can lead to
rapid evolution: individuals that are genetically better equipped for their environment tend to
survive and reproduce more prolifically than less fit individuals.
Lederberg and Tatum (1945) experiments in bacteria that could not make arginine or
tryptophan but exchanged genetic information and recovered functions; bacterial
transformation - Answer Sexual reproduction (conjugation) between bacteria resulting in
transformation and the ability to now produce colonies. Shows that there is genetic exchange
between bacteria
2 E. coli mutants:
One can't synthesize tryptophan [can make argenine]
One can't synthesize argenine [can make tryptophan]
Exchange genetic information -- Bacterial Transformation: naturally exchange DNA
R or resistance plasmids - Answer "Resistance genes"
Carry the genes to code for enzymes that specifically destroy or otherwise hinder the
effectiveness of certain antibiotics, such as tetracycline or ampicillin.
Exposing a bacterial population to a specific antibiotic, whether in a laboratory culture or within
a host organism, will kill antibiotic-sensitive bacteria but not those that happen to have r
plasmids with genes that counter the antibiotic. Under these circumstances, we could predict
that natural selection would cause the fraction of the bacterial population carrying genes for
antibiotic resistance to increase, and that is exactly what happens.
F plasmid and bacterial conjugation through pilus - Answer Conjugation: DNA is transferred
between two prokaryotic cells (usually of the same species) that are temporarily joined.
, In bacteria, the DNA transfer is always one-way: one cell donates the DNA, and the other
receives it.
In E. coli, a pilus of the donor cell attaches to the recipient. The pilus then retracts, pulling the
two E. coli cells together , much like a grappling hook. The next step is thought to be the
formation of a temporary "mating bridge" between the two cells, through which the donor may
transfer the recipient.
F Factor: a particular piece of DNA that gives the ability to form pili and donate DNA during
conjugation. The F factor of E. coli consists of about 25 genes, most required for the production
of pili.
The F factor can exist either as a plasmid or as a segment of DNA within the bacterial
chromosome.
F Plasmid: the F factor in its plasmid form.
Cells containing the F plasmid, designated F+ cells, function as DNA donors during conjugation.
Cells lacking the F factor, designated F-, function as DNA recipients during conjugation. The F+
condition is transferrable in the sense that an F+ cell converts an F- cell to F+ if a copy of the
entire F+ plasmid is transferred.
Conjugation: DNA is transferred between two prokaryotic cells (usually of the same species)
that are temporarily joined.
In bacteria, the DNA transfer is always one-way: one cell donates the DNA, and the other
receives it.
In E. coli, a pilus of the donor cell attaches to the recipient. The pilus then retracts, pulling the
two E. coli cells together , much like a grappling hook. The next step is thought to be the
formation of a temporary "mating bridge" between the two cells, through which the donor may
transfer the recipient.
F Factor: a particular piece of DNA that gives the ability to form pili and donate DNA during
conjugation
Wollman and Jacob (1957) mapping the sequence of bacterial genes with interrupted
conjugation - Answer Used interrupted mating technique: the chromosome of Hfr bacteria
were transferred linearly -> gene order and distance can be predicted b/c specific genes were
transferred/recombined sooner than others.
BUT order of genes transferred varied between Hfr strains -> origin of transfer is diff per Hrf
strain
Jacob and Monod (1961) bacterial operon - Answer Used interrupted mating technique and
identified clusters of related genes with adjacent promoter region and switch segment, the
operator.
Named this the bacterial operon.
Operator is controlled by repressor protein made by regulator gene (located elsewhere).
