review Flashcards
what are the 4 types of horizontal gene transfer mechanisms?
Conjugation:
DNA acquired directly from another bacterium
Transformation:
DNA acquired from external environment (not from another organism)
Transduction:
DNA acquired from a bacteriophage
Extracellular vesicles:
DNA delivered by vesicle
What is one thing that the donor needs in conjugation?
A conjugative mobile genetic element (MGE):
e.g. plasmid, genomic island, etc
What does a conjugative MGE have?
- sex pilus genes
- mobility (MOB) genes
Mobilizable MGEs (plasmids, genomic islands, etc) have _______ genes but DO NOT have _______ genes
Mobilizable MGEs (plasmids, genomic islands, etc) have MOB genes but DO NOT have sex pilus genes
If a bacterium has a mobilizable MGE and a conjugative MGE:
- conjugative MGE produces sex pilus
- mobilizable MGE produces mobility proteins
- mobility proteins deliver mobilizable mGE to the sex pilus that was produced by the conjugative MGE
- mobilizable MGE is transferred to another cell
If a bacterium just has a mobilizable MGE, this MGE ________ (can or cannot) be transferred to another cell through conjugation. Why?
If a bacterium just has a mobilizable MGE, this MGE CANNOT be transferred to another cell through conjugation (no sex pilus genes)
What is a transformation pilus
basically a DNA uptake pilus
Genomic islands are part of the bacterial chromosome that:
- was likely acquired through _______ gene transfer
- _________ (matches or does not match) the surrounding DNA (e.g. GC content)
- usually __________ (can or cannot) be transferred to other cells
Genomic islands are part of the bacterial chromosome that:
- was likely acquired through HORIZONTAL gene transfer
- DOES NOT MATCH the surrounding DNA (e.g. GC content)
- usually CAN be transferred to other cells (mobile genetic element)
Genomic island encompasses many different kinds of mobile genetic elements such as:
- transposable elements
- a plasmid that was integrated into the chromosome (e.g, F factor)
- others not covered in this class
Plasmid occur _________ the chromosome
a) inside
b) outside
b) outside
genomic islands are __________ of the chromosome
a) a part
b) not a part
a) a part of the chromosome
what are the types of genomic islands?
Conjugative genomic islands:
- encode everything needed to get cut out of chromosome, get transferred to another cell, and to insert into chromosome of that cell
Mobilizable genomic islands:
- Like mobilizable plasmids; don’t encode for conjugative machinery, but can use sex pilus produced by other MGEs
Is a plasmid a genomic island?
Only if its integrated into the chromosome, otherwise no.
What is monocistronic mRNA?
when there is only one gene between the promoter and the terminator it forms a short strand of mRNA that only contains one gene (one coding region) which is called a monocistronic mRNA
If a ribosome stalls when translating mRNA, can this change the conformation of mRNA? How/how not ?
Yes. Where the ribosome is bound will change how the mRNA folds over itself.
in order for translation to occur, the ribosome has to bind to the _____________, which is located where?
ribosome-binding site, which is located right before the start codon
What do sequestors do in translation?
they basically hide the ribosome binding site so that translation cannot begin
what do anti sequestors do in translation?
they prevent sequestors from forming
what do anti anti sequestors do?
block anti sequestors from forming (therefore sequestor can form)
what do genes in temporant phases undergo normally:
a) lytic cycle
b) lysogenic cycle
usually lysogenic
What is an F+ cell vs an HFr cell vs an F- cell?
F+ cell has an F factor plasmid in the cytoplasm
HFr cell has the F factor plasmid integrated into the bacterial chromosome
and we can go from one to the other, and in reverse. But, when we go in reverse, the F factor might take up some of the chromosomal DNA trying to form the F+ cell again, and this would be called an F’ CELL.
The F’ still has all the sex factor genes and mobility genes, so it can still produce sex pilus and transfer this to other cells. The result of this is that the receiving cell also receives the F’ so its also now considered an F’ cell.
