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conjugation 2


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What is conjugation?
1)Direct transfer of DNA btw two bacteria
2)Conjugation pilus
3)Replication of DNA being transfered(Rolling Circle)
4)Generally btw "related species" and within family members.
Donor cell is the ??
Recipient cell is the ??
What is the Episome?
It is the DNA transfered, it is like a large plamid.
Where is the information for Pilus formation and DNA replication?
On the plasmid.
What are the gene functions carried on plasmids?
1)Antibiotic resistance genes(called the 'R' plasmid)
2)virulence Genes(Virulence plasmids)
3)Antibacterial Genes-for competition(Colicins "Col Plasmids"
What is an Hfr cell?
A cell in which the episome recombine into the chromosome.
Can Hfr cells be donors?
What is a F' cell?
A cell in which the chromosom was integrated into the episome. Also may function as donors.
What is transformation?
Uptake of naked DNA.
What are two examples of species that are good at natural transformation?
1)Neisseria gonorrhoae
2)Streotococcus sp.
What is competence?
relative ability to take up DNA
What does competence do?
1)facilitate DNA uptake by converting DsDNA to ssDNA
2)manifest by proteins associated with the cell envelope(G+ wall G- inner membrane)
3)DNA is taken up generally as a ss molecle.
4)Once inside the host, the DNA can integrate into the genome.
Because this process occurs btw closely related species ___ ___ can occur.
homologous recombination
What is a artificial competence enhancement and what is it good for?
Calcium Chloride. It is good for small plasmid transformation.
What is transduction?
1)Virus mediated DNA transfer
2)bacterial viruses(Bacteriophage)
Studying bacterial viruses allowed for what?
Major contributions to be made in basic genetics and gene regulation.
What are the two possiblitites that may result from infection?
Lytic Cycle or the lysogenic cycle
What is the lytic cycle?
1)Viral DNA replication(host machinery)
2)Utilization of host protein synthesis machinery.
3)Packaging of viral nucelic acids into viral heads.
4)Final assembly.
5)Lysis and release from host.
What is the lysogenic cylce?
1)Viral DNA intergrates into host DNA("ATT" sequences)
2)Viral DNA is copied along with host
3)Transferred to offspring with chromosome
What can trigger the lysogenic cyle to enter the lytic cycle?
1)UV radiation
2)Chemical(DNA damaging agents) stress
Occasionally host(bacterial) DNA that is degraded may ??
get packaged into a viral head.
Upon a second infection the first hosts DNA is transferred into the ??
second host.
Sometimes viruses integrate their DNA into ??
host chromosome at specific sites
Upon starting a lytic cycle viral DNA excision may accidentally take some ??
host DNA with it. This host DNA and viral DNA may now be transferred to a second host.
Why is the phage packaged with both viral and bacterial DNA called a speciallized transducing phage?
Because only DNA sequences that flank the integrated viral DNA may be transferred to the new host.

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