Transposons, Plasmids, and Conjugation Flashcards
true or false, each gene encodes a single protein or RNA molecule
true
Other than a bacteria’s genome, how can it obtain additional sources of DNA?
1) via plasmids
2) genetic transfer from other bacteria
A DNA molecule that is physically seperate from the chromosomes is called? what info would this carry?
Plasmids
they usually contain non - essential genes
Explain what plasmids are
- extrachromosomal DNA
- usually circular
- self replicating (independent of chromosome)
- large plasmids have low copy number, small plasmids have high copy number
True or false, a cell can contain multiple copies of a plasmid AND multiple different plasmids
True
What is Curing?
The elimination of a plasmid. Curing inhibit the replication of a plasmid without affecting chromosomal replication.
what is an example of a curing agent?
Acridine Orange
What is an episome?
a type of plasmid that can exist separate from a chromosome but can also integrate itself into one
what are conjugated Plasmids
- contain genes for sex pili which make them self transmissible via conjugation
- they can transfer a copy of themselves to other bacteria
what are Non-conjugated Plasmids
- they are NOT SELF TRANSMISSIBLE
- however if they are in a cell with conjugated plasmids they can replicate and sneak a copy of themselves through pre made sex pilus
What significance does plasmids have in pathogenesis?
they can create a rapid spread of resistance to anti- biotic drugs
What is a well known conjugative plasmid in E. Coli?
Fertility factors aka F factors. These are also episomes.
what are Tra genes?
short for transfer genes which are the genes responsible for the transfer of conjugated plasmids. (make sex pilus)
What is a resistance factor?
- R factors are plasmids that code enzymes that destroy anti-biotic drugs
- single gene can code resistance to many drugs (up to 8 anti-biotics)
Why is the R factor said to be promiscuous?
they are conjugated plasmids that can transfer their genetic material to ANY bacteria, not just their own species
what is a bacteriocin?
A protein that is produced by one strain of bacteria that is pathogenic to strains very similar to the strain that produces it.
What are Col plasmids?
- they encode Colicin which is a bacteriocin to E. Coli
- it kills E. Coli
- considered Competitive (c) factor
Are Col plasmids conjugative?
Sometimes, not always
What are virulence and metabolic plasmids?
Virulence - carry pathogenic genes
metabolic - genes that code for metabolic processes
ex genes for Nitrogen fixation in Rhizobium
What causes travellers diaherria?
Virulence plasmids
What is transposition?
the movement of pieces of DNA from one part of the genome to another. Transposons are the sections of DNA that encode for transposition.
What are the two types of transposable elements (Transposons)
1) insertion sequences
2) composite transposons
explain insertion sequences
transposon that encodes only for transposase enzymes. In other words only contains info to move DNA.
Called IS elements
Explain composite transposons
contain DNA that encode enzymes to move DNA and other genes often R factors. composite transposons are flanked on both sides by IS elements