basic challenge 2: evolution of bacteria Flashcards
Name 5 mechanisms for antibiotics.
- cell wall synthesis interference
- inhibition of protein synthesis
- alteration of cell membrane
- inhibition of nucleic acid synthesis
- antimetabolite activity
What are mobile genetic elements?
MGE are a type of moving genetic material that can move around in a genome or jump across different genomes.
What does the MGE consist of?
- inverted repeats
- direct repeats
- the genetic material itself
What enzyme moves the MGE + recognition and mechanism
transposase. the MGE consist of the genetic material between inverted repeats(IR) and Direct repeats. transposase recognises the IR and cuts it at that site. After transportation, the gaps between the IR and other sequences is filled with direct repeats
What are the different horizontal gene transfers?
- transformation (via the environment)
- conjugation (cell-to-cell)
- transduction (bacteriophages)
How does transformation work in the horizontal gene transfer
sex pilus sticks out the cell membrane, When the pilus comes in contact with DNA, it contracts and brings the DNA inside. This can be successfull or not and most bacteria are capable of transformation.
How does conjugation work in horizontal gene transfer?
This goes, like transformation, with the sex pilus. The pilus from F+ (bacteria that do contain the specific plasmid) comes in contact with a pilus from a bacteria that is F- (does not contain the plasmid). After this, the plasmid in the F+ is replicated by the rolling circle mechanism. Then the replicated plasmid gets transferred through the T4SS to the F- bacteria. This then becomes the F+ bacteria
How does transduction work?
There are 2 types of transduction: generalised transduction and specialised transduction.
- Generalised transduction: the genes of the bacteriophage does not integrate in the bacterial DNA but replicates outside of it. This will result in bacteriophages with either only the bacterial DNA or only the bacteriophage DNA.
- Specialised transduction: The genes of the bacteriophages integrate in the bacterial DNA and only specific portions can be transferred. This will result in bacteriophages with a mix of DNA of the bacteria itself and the bacteriophages.
What are the types of virulence factors?
- ability to inade host cells
- abillity to evade the innate immune system (+complement)
- abillity to evade the adaptive immune system
- ability to adjere and resist physical removal
- ability to contact other host cells
- ability to compete for nutrients
What is a super antigen?
type of antigen that can overactivate the immune system by activating non specific T-cells. This can result in massive cytokine release
What are the types of secretion systems?
One step:
- T3 (needle like injectors)
- T4 (conjugation)
-T6 (by gram negative, deliverance of toxins)
Two step
What the the difference between the core genome and pan genome?
core genome: minimum of genomes needed to survive
pan genome: this is acquireed by HGT, a bacteria who has been through a long evolution, will have a large pan genome.
What does pan genome consist of?
the pan genome consist of accessory genes. these can be antimicrobial resistance genes.
What are pathogenicity islands?
that are codes for virulence factors. this is a type of MGE.
What is the GC content?
number of strand guanine cytosine sites divided by the total DNA sequence length. This can be between 13-75%. Example:
cttagcccgat
This in total consists of 6 c’s and g’s. the total length is 11. 6/11 is 54,5%
