Bacterial Genetics Flashcards
What is a spontaneous mutation?
A mistake during DNA replication can substitute one base for a different base
What can a spontaneous mutation involve?
Can change a single amino acid, or add a stop codon and inactivate the whole protein
What does removal or addition of a nucleotide change?
The translational reading frame
Is it better to change one nucleotide, or a group of 3?
A shift or change of a group of 3 nucleotides has a less damaging effect on the strand.
In which 3 ways can a mutation be induced?
UV or X-ray radiation, or chemicals that alter DNA
What is the effect of vertical gene transfer on progeny?
All the progeny of that bacteria have the new DNA sequence
At what rate do spontaneous mutations occur?
Occurs between 1 in 104 and 1 in 1012 in a given gene when a cell divides
What are the names of the two types of “directional” gene transfer that contribute to bacterial diversity?
Horizontal and vertical.
What are the 3 types of Horizontal Gene Transfer?
- Transformation
- Transduction
- Conjugation
What is Transformation?
The transfer of genetic material from transfer of naked DNA
What is Transduction?
The transfer of genetic material from one bacterium to another by a bacteriophage
What is Conjugation?
The transfer of genetic material from one bacterium to another by means of conjugation pili
What are the 3 steps of Transformation?
- Cells rupture during the stationary and death phase (The chromosome breaks into small pieces)
- Recipient cell picks up piece of the naked DNA
- The naked DNA is integrated onto the recipient chromosome
What condition is required for natural transformation to occur?
Natural transformation occurs when bacterial cells are “competent”
When is bacterial competence?
Competence is a condition in which bacterial cells are capable of taking up and integrating larger fragments of DNA