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Genetic Transfer and Recombination in Microbiology

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  • What is genetic recombination in bacteria?
    Genetic recombination is the exchange of genes between two DNA molecules to form new gene combinations on a chromosome, often involving crossing over.
  • What enzyme catalyzes the joining of DNA strands during recombination?
    The RecA protein catalyzes the joining of donor and recipient DNA strands during genetic recombination.
  • Difference between horizontal and vertical gene transfer
    Vertical gene transfer passes genes from parent to offspring, while horizontal gene transfer transfers genes between cells of the same generation.
  • What are plasmids?
    Plasmids are self-replicating, circular DNA molecules found mainly in bacteria that carry genes, often for survival advantages like antibiotic resistance.
  • What is the F factor in bacteria?
    The F factor is a conjugative plasmid carrying genes for sex pili and plasmid transfer during bacterial conjugation.
  • Why are R factors clinically important?
    R factors are plasmids that carry genes encoding resistance to antibiotics and toxins, contributing to antibiotic-resistant bacterial populations.
  • What role do plasmids play in bacterial pathogenicity?
    Plasmids can carry genes for toxin production and attachment factors, turning harmless bacteria into pathogens.
  • What are transposons?
    Transposons are DNA segments that can move within or between DNA molecules, sometimes carrying genes like antibiotic resistance.
  • What enzyme do transposons encode for movement?
    Transposons encode transposase, an enzyme that cuts and reseals DNA during transposition.
  • Why are transposons called 'jumping genes'?
    Because they can move from one DNA location to another, inserting themselves into different sites within chromosomes or plasmids.
  • What is bacterial transformation?
    Transformation is the uptake of naked DNA from the environment by a bacterial cell, which can then integrate it into its chromosome.
  • What was Griffith's experiment demonstrating transformation?
    Griffith showed that dead encapsulated bacteria could transfer genetic material to live nonencapsulated bacteria, making them virulent.
  • Which molecule was identified as the transforming factor in bacteria?
    DNA was identified as the transforming factor responsible for genetic change in bacteria.
  • What does it mean for a bacterial cell to be competent?
    A competent cell can take up donor DNA from its environment during transformation.
  • What is bacterial conjugation?
    Conjugation is the transfer of genetic material between bacteria via direct cell-to-cell contact, often mediated by plasmids.
  • What is an F+ cell?
    An F+ cell contains the F factor plasmid and can donate it to an F- cell during conjugation.
  • What is an Hfr cell?
    An Hfr cell has the F factor integrated into its chromosome and can transfer chromosomal genes to an F- cell during conjugation.
  • Do bacteria reproduce during conjugation?
    No, conjugation transfers DNA between cells but does not involve bacterial reproduction.
  • What is transduction in bacteria?
    Transduction is the transfer of bacterial DNA from a donor to a recipient cell inside a bacteriophage (virus) particle.
  • What is generalized transduction?
    Generalized transduction occurs when any bacterial DNA fragment is accidentally packaged into a phage and transferred to another bacterium.
  • How can bacteria acquire toxin genes via transduction?
    Bacteriophages can carry toxin genes from one bacterial host to another during specialized transduction.