Advanced Microbiology - Transformation and Homologous Recombination

These flashcards cover key terms and concepts related to transformation and homologous recombination as discussed in Advanced Microbiology.

Transformation

Direct uptake of 'naked' DNA from the environment by a cell.

Wild type (WT)

Normal members of a species.

Mutant (∆)

An organism that is genetically distinct from the normal members of a species.

Competent Bacteria

Bacteria that can take up DNA from their environment.

Natural Transformation

Transformation that occurs without special chemical or electrical treatments.

Induced Transformation

Transformation that requires special chemical treatment or electrical application to facilitate DNA uptake.

Griffith’s Experiment

An experiment that demonstrated that dead pathogenic bacteria could transfer a 'transforming principle' to live non-pathogenic bacteria.

Transformant

A recipient cell that has taken up DNA and incorporated it into its own genome.

Quorum sensing

A mechanism where bacteria communicate and coordinate their behavior based on population density.

Competence Pheromones

Small peptides secreted by bacteria that promote competency to take up DNA.

DNA Uptake Sequence (DUS)

Specific sequences required by some Gram-negative bacteria for DNA uptake.

Homologous Recombination

A process that allows for genetic material exchange during DNA repair.

Artificially Induced Competence

Induction of competence in bacteria that are not naturally competent, often using calcium ions or electroporation.

Double-Stranded Break Repair

Mechanisms that fix DNA breaks, including homologous recombination and nonhomologous end joining.

Avery, McCarty, and MacLeod

Scientists who identified DNA as the 'transforming principle' responsible for genetic transformation.

Nucleases

Enzymes that degrade DNA, allowing for single-stranded DNA to be translocated inside a cell.

RecA

A protein involved in homologous recombination that facilitates the repair of DNA.

Amplification of DNA

Duplication of a specific gene or chromosome segment through recombination events.

Steps of Transformation

1. DNA is released into the environment.

2. Competent bacteria take up the DNA.

3. DNA is integrated into the bacterial genome through homologous recombination.

Visual Aid: Transformation Process

Illustrate the transformation process showing:

• Release of DNA from dead bacteria

• Uptake by competent bacteria

• Integration into the genome.

Types of Competence

1. Natural Competence:
   • Occurs without artificial interventions.
2. Artificial Competence:
   • Induced using methods like electroporation or heat shock.

Applications of Transformation

1. Genetic Engineering: Introducing genes for desired traits.
2. Gene Therapy: Correcting defective genes in clinical settings.
3. Production of Recombinant Proteins: Utilizing transformed bacteria for protein synthesis.

Quorum Sensing Mechanism Steps

1. Bacteria release signaling molecules (autoinducers).
2. As population increases, concentration of autoinducers rises.
3. Once a threshold is met, genes related to behavior are activated.