Prokaryote genetics Flashcards
What is the function of MukBEF in prokaryotes?
- extrudes and constrains loops
- indicates use of supercoiled loops in prokaryotes
- Radiate from axial position
- topologically independent indicating some form of loop binding domain
Describe the prokaryotic genome scaffolding region
- Some loops defined by REP(repetitive, extragenic, palindromic)
- Each REP contains several domains for gyrase attachment
How are negative supercoiling levels maintained?
-antagonistic interaction between gyrase and topoisomerase I
How is the trp operon regulated?
- Mutually exclusive hairpins
- Abundance of amino acids first hairpin can’t form due to speed of translation
How do difference sized/shaped bacterial plasmids interact?
- Can be linear or circular
- Small in high abundance or inverse
- Can resemble mini-chromosomes sometimes
What examples of functions can plasmids provide?
- Antibiotic resistance
- Heavy metal resistance
- Radiation damage resistance
- Metabolic properties
- Toxin production
Do all plasmids interact equally with their hosts?
- Some selfish and competing for control over host
- Some circumstantial allow hosts to survive in specific environments
How does site specific recombination differ from homologous recombination?
- Site specific recombination doesn’t require significant homology between recombination sites
How do plasmids deal with multimers?
- Oxford model: sites must interwrap which is more likely when sites are on same plasmid
- Cambridge model: negative supercoiling allows ArgR and PepA to recombine
Is plasmid conjugation limited to same species?
- No can even target yeast and some mammalian cells
How does conjugation increase the number of copies?
- Adds a new host
- Extra round of replication
How do transposase genes transport other genes?
- Flanking by two transposases acts as cut and paste
- Allows any prokaryotic gene, becomes composite gene, to be transferred
What is the Tn3 family?
- Transposable element family found on F plasmid
- Often include resistance to several antibiotics
- Often acts as origin of antibiotic resistance
