11 November: Mechanisms of Genetic Exchange Flashcards
What characteristics of bacteria lead to the spread and an increase in antibiotic resistance?
- High numbers
- Single copy of a chromosome
- Transcription and translation combined
- Short generation time
Three mechanisms of bacterial genetic exchange
Conjugation, transformation and transduction
Conjugation
Type of horizontal gene transfer
- Plasmid-encoded pilus attaches to another cell + transfers copy of plasmid to another cell
Three types of plasmids
R plasmids (antibiotic resistance), Virulence plasmas (toxins or other disease causing products), and transmissible plasmids (transfer copies of themselves to other cells)
F plasmid
Encodes protein that makes pilus
F+ cell (Donor Cell)
Has the F plasmid
Origin of Transfer
Sequence of DNA that tells F plasmid where to start making DNA and when to start moving into another cell
F- Cell (Recipient cell)
Does not have the F plasmid, and receives it from the F+ plasmid which makes it a F+ cell
Hfr Cells
High frequency of recombination, a type of F+ cell whose plasmid is incorporated into the chromosome
Homology
Regions of the same sequence of DNA that can help genetic material zip together (swapping DNA)
Transformation
Horizontal gene transfer
- Recipient cell takes up DNA from the environment
- Used for genetic engineering by artificially inducing competence
Horizontal Gene Transfer
Not from parent to child, but like sibling to sibling, human to human
Competent cells
Cells that take up DNA
What does transformation require?
Homologous recombination
Transduction
Horizontal gene transfer
- Using bacteriophage to carry host bacterial DNA to recipient cell, infecting that new cell
- Requires homologous recombination
