What is unique about transduction compared to normal bacteriophage inection?
answer
Transduction transfers DNA from the chromosome of one cell to another
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How is generalized transduction different from specialized transduciton?
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Generalized transduction is initiated during lytic cycle of virulent bacteriophage; specialized trasnduction is initiated during the lysogenic cycle of a temperate bacteriophage.
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A transducing phage...
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contains fragments of the host chromosome instead of the viral genome.
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When a transducing phage interacts with a new host cell,
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the DNA from the previous host can recombine with the new host chormosome
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How does n F+ cell differ from an Hfr cell?
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Hfr strains have the F plasmid integrated into the chromosome
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Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?
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Conjugation is typically disrupted before the fertility factor can be transferred.
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Which of the following is a characteristic of an F+ cell?
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Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F-cell.
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What benefit does the F- strain receive from mating with an Hfr stain?
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It acquires new, potentially beneficial genes from the Hfr strain
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Which of the following is a method of vertical gene transmission?
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Cell divison
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Frederick Griffith did experiments on genetic transformation. Which of the following statements about his experiments is accurate?
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Griffith found that hereditary material released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent
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A student states that the trp gene is located at 26 minutes. What does this mean?
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It takes 26 minutes for the gene to be transferred during conjugation.
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If argG, argR, and argE are all required to make a cell able to metabolize arginine, how long would it take for an arg- recipient to become arg+?
answer
87 minutes
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If conjugation was allowed to be carried out for 25 minutes, which genes would be transferred to the recipient strain?
answer
lac
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How does conjugation help geneticists map the genomes of bacteria?
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It provides them with the relative position of the genes on the chromosomes.
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If gene X transferred at 90 minutes fir E. Coli, what conclusion could you make about gene X?
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Gene X is close to the fertility factor on the Hfr chromosome, but is near the end of the chromosome transfer
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What is the function of the conjugation pilus?
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It pulls the F+ and the F- cells together
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What is required by an F- cell to become an F+ cell?
answer
F plasmid
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What is the key difference between donor cells and recipient cells?
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an F plasmid
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What cellular marcomolecule is the fertility factor comprised of?
answer
Nucleic Acid
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At which point does a recipient cell become an F+ cell?
1. Fusion of the cell membranes
2. Attachment of the sex pilus
3. Transfer of the single stranded F factor
4. Pulling of donor and recipient cells together
5. Formation of the complementary strand of the F factor
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5. Formation of the complementary strand of the F factor
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Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate?
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Conjugation does not result in the formation of new offspring
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What must occur for bacterial conjugation to take place?
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The cells must come into contact with each other
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Which statement about conjugation is false?
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Conjugation is a process of bacterial reproduction
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Based on the animation, what is transferred during bacterial conjugation?
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a bacterial plasmid
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A recombinant cell
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is a cell that receives DNA from an outside source and incorporates it into its own
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What is the hallmark of all horizontal gene transfers?
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Transfer of DNA between organisms of the same generation
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Which of the following is an example of horizontal gene transfer in bacteria?
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Transduction, conjugation, and transformation
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Competent cells are cells that
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can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination
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Mice that are injected with only the R strain of Streptococcus pneumoniae
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stay healthy, because their immune systems can kill this strain easily.
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What characteristic of the S strain allows it to evade the immune system of the mice?
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The cells have a capsule
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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?
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The R strain picked up the S strain DNA, enabling it to produce a capsule
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Which finding is most surprising from Griffith's experiments?
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S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains
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How is a complex transposon different from a simple transposon?
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They have 2 simple transposons with another DNA sequence between them.
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Why does a complex transposon often contain an extra piece of DNA between the 2 insertion elements?
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It is often a gene that confers a survival advantage to the host, such as antibiotic resistance.
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How would you be able to determine if the Tn5 transposon you put into a bacterium integrated into the host genome?
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If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin.
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Insertion sequences target which areas on a target DNA sequence?
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A sequence of nucleotides identical to the inverted repeat sequence found on the insertion sequence itself
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What makes an insertion sequence different from other DNA sequences found in a cell?
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They are capable of effecting their own movement from one location to another on DNA
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If the gene that codes for transposase is mutated so that it no longer produces the fully functional enzyme, how will the insertion sequence be affected?
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The insertion sequence would lose its ability to effect its own movement
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How does replicative transposition differ from cut-and-paste transposition?
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Replicative transposition results in the transposon being copied to a new location; in cut-and-paste transposition, the entire transposon moves to the new location.
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Which type of transposon would contain a gene for transposase?
answer
Both simple and complex transposons
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How do complex transposons differ from simple transposons?
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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.
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Horizontal Gene Transfer
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*Gaining a single new gene sequence from outside of the cell
*Infection by a prophage containing a partial bacterial operon
*Uptake and insertion of a transposable element carrying foreign genes
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Vertical Gene Transfer
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*Mitosis to form 2 daughter cells
*Two haploid cells fusing to form a diploid cell
*Binary fission of bacterial cell
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Consider the following statement: Bacteria can exchange genetic material through conjugation without the need for any protein structures or control mechanisms. Is this statement True or False?
answer
False
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If the inserted sequence had been complete except for missing the last 54 nucleotides (and thus the stop signal), would a working protein be possible?
answer
Both yes and no are probable. DNA sequencing after the inserted gene would need to be done to see whether any stop signals would be in the correct reading frame or what possible amino acids would be added to the protein.
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