Flashcards in Bacterial Genetics Deck (56):
How do complex transposons differ from simple transposons?
A: Complex transposons are found in multiple locations in the target DNA; simple transposons are found only in one location.
B: Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon itself.
C: Complex transposons code for transposase; simple transposons do not.
What is the difference between an F+ and an Hfr bacterium?
A: F+ bacteria have an F plasmid that includes some nuclear genes, while Hfr (high frequency recombinant) bacteria have an F plasmid with only the essential genes for conjugation.
B: F+ bacteria have a plasmid with only the essential genes for conjugation, while Hfr (high frequency recombinant) bacteria have an F plasmid that includes some nuclear genes.
C: F+ bacteria have an integrated F plasmid, while Hfr bacteria have a nonintegrated F plasmid.
D: F+ bacteria have a nonintegrated F plasmid, while Hfr bacteria have an F plasmid that is integrated into their main chromosome.
What must occur for bacterial conjugation to take place?
A: The cells must come into contact with each other.
B: One of the cells must be E. coli.
C: Each cell must contain a plasmid.
D: The cells must transfer RNA.
Which statement about conjugation is false?
A: E. coli is the model for bacterial conjugation.
B: After conjugation, each cell involved has a copy of the shared DNA.
C: Conjugation is a process of bacterial reproduction.
What is unique about transduction compared to normal bacteriophage infection?
A: The bacteriophage does not erupt from an infected cell during transduction.
B: The bacteriophage takes fragments of the cell with it during transduction.
C: Transduction transfers DNA from the chromosome of one cell to another.
How is generalized transduction different from specialized transduction?
A: Only one specific host gene is transferred in both specialized transduction and generalized transduction.
B: Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage.
C: Specialized transduction uses animal viruses instead of bacteriophage.
D: Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.
A transducing phage
A: is a lysogenic bacteriophage.
B: cannot infect new host cells.
C: has a viral coat made of host proteins.
D: contains fragments of the host chromosome instead of the viral genome.
During conjugation, if an Hfr cell is mated with an F- cell, why will the F- cell remain F-?
A: The cells would not stay in contact long enough for the entire Hfr genome to be transferred.
B: The recipient will not remain F-, it will become F+.
C: The donor cell is not an F+ cell, it is Hfr.
D: The recipient will not remain F-, it will become Hfr because of the donor cell genome.
How do restriction enzymes cut DNA sequences?
A: They have the ability to cut DNA randomly.
B: They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.
C: They cut DNA at sequences that have lots of adenine bases.
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?
A: To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene
B: To insert a desirable gene
C: To replace a defective gene with a working gene
D: To remove an undesirable gene
Which of the following attaches the target gene to a desired location?
A Chromosomal DNA
B Restriction enzymes
D DNA ligase
Why would a recombinant DNA molecule be inserted into a host cell?
A: Restriction enzymes can only be used inside of a cell.
B: It can be copied, transcribed, and translated into a desired protein.
C: It can protect the recombinant DNA.
D: Plasmids cannot be isolated outside of a host cell.
Which process listed below does NOT require homologous recombination to maintain the new genetic material in the recipient cell?
A transduction by a dsDNA phage Mu
B conjugation of a linear piece of DNA
C transformation of a linear piece of DNA
D gene transfer through a genetic transfer agent
Which of the following proteins is NOT required for homologous recombination?
C proteins having helicase activity
Consider the following experiment. First, large populations of two mutant strains of Escherichia coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result?
A The colonies may be due to recombination.
B The colonies could be due to either recombination or back mutation.
C The colonies may be due to back mutation (reversion).
D The colonies being due to recombination or back mutation is not possible.
Homologous recombination has been observed in
A Archaea, Bacteria, and Eukarya.
A deleterious mutation in recA results in
A an increase in homologous recombination.
B no change in either general or specific recombination.
C a decrease in specific recombination.
D a decrease in homologous recombination.
recA is involved in DNA repair and homologous recombination
The process in which related DNA sequences from two different sources are exchanged is called
A homologous recombination.
C phage conversion.
Mice that are injected with only the R strain of Streptococcus pneumoniae
A stay healthy, because their immune systems can kill this strain easily.
B become sick for prolonged periods of time.
C are killed, because R strain cells are deadly.
What characteristic of the S strain allows it to evade the immune system of the mice?
A The cells have a capsule.
B They are resistant to heat.
C They are genetically engineered to be resistant to killing.
D They are naturally competent.
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells?
A The R strain cells picked up the capsules from the S strain cells.
B The R strain picked up the S strain DNA, enabling it to produce a capsule.
C The S strain fused with the R strain, making it resistant.
D The S strain was revived by the presence of the host’s immune system.
Which finding is most surprising from Griffith’s experiments?
A S strain cells kill the mice.
B S strains are able to escape phagocytosis.
C S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.
D R strain cells fail to produce a capsule.
Transformation and homologous recombination allow for the formation of heteroduplex DNA. Which of the following would occur during DNA replication of this molecule?
A Both daughter strands are complementary to the parent DNA molecule.
B One daughter strand is complementary to the recombinant DNA molecule, while the other daughter strand is complementary to the parent DNA molecule.
C Both daughter strands are complementary to the recombinant DNA molecule.
D None of the answers are correct.
Integration of linear transforming DNA into the chromosome
A almost never occurs because restriction endonuclease will degrade the DNA before it is integrated.
B is not required for the expression for the transformed genes.
C is catalyzed by the RecA gene.
D only occurs in laboratory-based systems in artificial competent cells.
High-efficiency natural transformation
A is common in Bacteria and Archaea.
B requires specialized DNA uptake, DNA binding, and integration proteins.
C is only common in Archaea.
D usually involves plasmids.
The minimal amount of genetic information required for specialized transduction would include
A a helper phage.
B the att region, cos site, and a helper phage.
C the att region.
D the cos site.
Lysogeny probably carries a strong selective advantage for the host cell because it
A prevents cell lysis.
B confers resistance to infection by viruses of a different type (or strain).
C confers resistance to infection by many virus types and prevent cell lysis.
D confers resistance to infection by viruses of the same type.
Plasmids that govern their own transfer are known as
Which of the following would NOT be a trait of a resistance plasmid?
A It may carry heavy metal resistance genes.
B It may carry antibiotic resistance genes.
C It may undergo genetic recombination.
D It increases the host's growth rate.
Hfr strains of Escherichia coli
have an integrated F factor.
have the F factor as a plasmid.
do not possess an F factor.
transfer the complete F factor to recipient cells at a high frequency.
F+ strains of Escherichia coli
A do not have an F factor.
B have the F factor as a plasmid.
C transfer the F factor to recipient cells at a high frequency.
D have an integrated F factor.
F- strains of Escherichia coli
A transfer the F factor to other strains at a high frequency.
B have an integrated F factor.
C do not have an F factor.
D have the F factor as a plasmid.
All Hfr strains integrate into the chromosome at
A the same locus most of the time, although there may be some variation.
B the same locus.
C several specific sites.
D loci that cannot be accurately determined.
The enzyme transposase may be coded for by insertion sequences on a
C chromosome, phage, or plasmid.
Which of the following features are common to transformation, transduction, and conjugation?
(1) unidirectional transfer of genes
(2) incomplete gene transfer
(3) homologous recombination
(4) meiosis occurring in the recipient
Which of the following features are common to transformation, transduction, and conjugation?
A 1, 2
B 1, 2, 3
C 1, 2, 4
D 3, 4
What is the function of the conjugation pilus?
A It pulls the F+ and F- cells together.
B It carries the chromosome of F- cells.
C It converts F- cells into F+ cells.
D It contains an F plasmid.
What is required by an F- cell to become an F+ cell?
A Conjugation pilus
B An F- cell to be a recipient
C F plasmid
D F+ chromosome
What is the key difference between donor cells and recipient cells?
A An F plasmid
B A chromosome
C Cell membranes
What cellular macromolecule is the fertility factor comprised of?
A Nucleic acid
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?
A Conjugation is typically disrupted before the fertility factor can be transferred.
B The transferred genes typically recombine with the recipient chromosome.
C The cell membranes between the two strands never fuse together.
D Hfr strains lack fertility factor.
Which of the following is a characteristic of an F+ cell?
A Presence of a fertility factor
B Ability to synthesize sex pili
C Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
D Ability to mate with an F- cell
You have performed the following mating experiment using Hfr and F- strains of Escherichia coli:
Hfr (thr+ leu+ gal+ strs) × F- (thr- leu- gal- strr). Which of the following selective media would you use to score recombinant colonies?
A minimal medium + threonine
B minimal medium + streptomycin
C minimal medium + streptomycin + threonine
D minimal medium
The positions of genes on a genetic map are marked according to
A plasmid may
A be transferred cell-to-cell during conjugation.
B be integrated into the chromosome.
C replicate independently of the chromosome, integrate into the chromosome, or be transferred cell-to-cell during conjugation.
D replicate independently of the chromosome.
Consider conjugation in Escherichia coli. In which of the following matings would chromosomal genes be transferred most frequently?
A F+ × F-
B Hfr × F+
C F- × F-
D Hfr × F-
Which of the following is most similar to lysogeny?
A F' state
B Hfr state
C F- state
D F+ state
Hfr means high frequency of ________, and these cells are capable of transferring genes from their ________ to other cells.
A transduction / chromosome
B recombination / chromosome
C transduction / plasmids
D transformation / chromosome
The F (fertility) plasmid contains a set of genes that encode for the ________ proteins that are essential in conjugative transfer of DNA.
C SOS repair
Horizontal gene transfer in Archaea
A frequently occurs in nature and has been used to perform genetic studies in the laboratory as well.
B is infrequent in nature and therefore difficult to use for genetic studies in the laboratory.
C has not been documented, thus all genetic studies of archaea are done via genomic sequencing.
D frequently occurs in nature, but there are very few laboratory studies because archaea do not cause human disease.
Transposition is a(n)
A site-specific recombination event.
B general recombination event.
C homologous recombination event.
D analogous recombination event.
In the bacterial world, a gene located on which of the following would be the LEAST likely to be transferred?
A the chromosome
B R factor
D the phage Mu
Genetic recombination involving insertion sequences typically results in what type of mutation?
A base-pair substitution mutation
B frameshift mutation
C silent mutation
D base-pair deletion mutation
When a transposon is cut from one location in genome and pasted into a new location, it is called __________.
A conservative transposition
B replicative transposition
C cut and paste transposition
It is not increasing the number of transposons, so it is conservative.
How is a complex transposon different from a simple transposon?
A Complex transposons have one very long insertion sequence.
B They have two simple transposons with another DNA sequence between them.
C They always integrate in multiple copies into the host genome.
D Complex transposons code for different types of transposase.
Why does a complex transposon often contain an extra piece of DNA between the two insertion elements?
A It is often a gene that confers a survival advantage to the host, such as antibiotic resistance.
B The insertion elements require a certain distance between them to function properly.
C It prevents degradation of the whole transposon.