Mechanisms of genetic exchange in bacteria Flashcards
Where are essential genes found?
In chromosomes
Where are non-essential genes found?
In plasmids
Plasmids replicate independent of chromosomes. True or false?
True
Bacteria cannot survive without plasmids. True or false?
False - as they carry non-essential genes, bacteria can still survive without them, however they provide bacteria with a competitive advantage e.g. resistance
Rate of evolution is influenced by unicellularity. True or false?
True
What is transformation?
A genetic transfer process by which DNA is incorporated into a recipient cell and brings about genetic change
Cells that are capable of taking up DNA and being transformed are referred to as _________
competent
What can be used to force cells to take up DNA?
Electricity (electroporation)
Mainly gram ______ bacteria are competent
positive
What is transduction?
The transfer of DNA from one cell to another by a bacteriophage
What are the two modes of transduction?
Specialised
Generalised
What is generalised transduction?
DNA from any portion of the host genome is packaged inside the virion
What is specialised transduction?
DNA from a specific region of the host chromosome is integrated directly into the virus genome
Generalised transduction is a rare event that happens i.e. low efficiency. True or false?
True
What is conjugation?
Mechanism of transfer that involves cell to cell contact
Bacteria need plasmids for conjugation to take place. True or false?
True
Does the recipient cell contain the conjugative plasmid?
No
Sex pilus is essential for ___________. It is only produced by the donor cell
conjugation
F plasmid is an _______ - it can integrate into host chromosome
episome
What are cells possessing a non-integrated F plasmid called?
F+
What are cells possessing an integrated F plasmid called?
Hfr
What does Hfr mean?
High frequency of recombination
Presence of an F plasmid results in alteration of _________ so that cell can no longer act as a recipient in conjugation, it can only be a donor
surface receptors
F plasmid contains ____ genes that encode transfer function
tra
