Lack genetic diversity compared to sexual reproduction (e.g., humans with meiosis).
This chapter explores methods bacteria use to introduce genetic diversity.
Gene Transfer
Vertical Gene Transfer
Hereditary transfer of DNA to the next generation.
Horizontal/Lateral Gene Transfer
Unique to prokaryotic cells.
Bacteria can exchange genetic material with peers, not just offspring.
This process involves donors and recipients and results in recombination.
Transformation in Bacteria
Definition
The ability of bacteria to take up DNA from their environment and incorporate it into their genome.
Historical Context
Discovered by Frederick Griffith in 1928 using strains of Streptococcus pneumoniae.
Griffith's experiment demonstrated transformation using rough (non-virulent) and smooth (virulent) bacterial strains.
Griffith's Experiment
Experiment Details
Heat-killed smooth bacteria: Non-virulent when injected into mice.
Live smooth bacteria: Virulent and lethal to mice.
Live rough bacteria: Non-virulent and safe for mice.
Combination of heat-killed smooth and live rough bacteria: Resulted in death of mice due to transformation.
Transformation Explanation
Heat-killed smooth bacteria released DNA fragments into the environment.
Rough bacteria incorporated these fragments, gaining a capsule and becoming virulent.
Competent Bacteria
Competence Factor
Proteins that allow bacteria to take in DNA and remain healthy.
Commercial Use
Competent bacteria can be purchased for genetic experiments.
Genetic Recombination
Process
Competent bacteria can incorporate environmental DNA, leading to genetic recombination.
Results in genetic diversity, potentially enhancing abilities like antibiotic resistance.
Significance
The chapter highlights the methods through which bacteria increase genetic variability, with implications for biotechnology, including vaccine and medicine production.