Bacterial genetics, mobile elements and evolution Flashcards
What is HGT/ Horizontal Gene transfer?
The movement and rearranging DNA in prokaryotes such as bacteria
What are MGE?
MGE/ mobile genetic elements are a type of DNA that can move around and within the genome
What are some examples of MGE in the genome?
Transposons
Retrotransposons
DNA transposons
Insertion sequences
Plasminds
Bacteriphages
What is the total of all mobile genetic elements in a genome referred as?
May be referred as the mobilome
What is a plasmid?
A circular piece of self-replicating DNA located outside of the bacterial chromosone
What two processes does HGT require?
- Physical movement of DNA
- Incorporation into the receiving genome so it is stably inherited
What are the three mechanism of gene transfer?
- Conjugation
- Transformation
- Transduction
What is conjugation/ How does it work?
a summary
Conjugation is gene transfer by means of plasmids and conjugative pilli
* It requires close contact between bacteria
* it occurs primarily between closely-related strains or species
* the donor needs to possess the capacity to create conjugative pilli
* it is the most important mechanism for translocating DNA between bacteria
What is transformation?
a summary
- The uptake of free DNA by competent bacteria
- It does not require close contact between bacteria
- The free DNA usually comes from dead bacteria
What is the definition of competence
In terms of bacteria
A physiological state, often highly dependent of the environment which enables bacteria to uptake macromolecules that bind to its surface
What is fluoroquinalone resistance?
A single point mutation that can result in resistance and significant differencea in bacterial fitness
What is the difference between a transposon and a retrotransposon?
- DNA transposon is just excised from its initial DNA and then re-inserted
- Retro/ RNA transposons move via an RNA intermediate
What are the three steps involved in HGT?
- T- Transfer (the mechanism of gene transfer)
- I- Integration (mechanism of gene incorporation)
- E-Element (the mobile element involved)
What is the definition of lateral/ horizontal gene transfer?
The process where DNA from one cell is physically transferred
from one cell to another without an absolute requirement for cell
division and the incorporation of that DNA into the recipient’s
genome such that it can be stably inherited
