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Ecoli Bacteria… remember that 25% of your feces is E coli bacteria….

Ecoli Bacteria… remember that 25% of your feces is E coli bacteria…. Plasmids. A circular piece of DNA that is not a part of the bacteria’s genome. It is ‘extra-chromosomal.’.

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Ecoli Bacteria… remember that 25% of your feces is E coli bacteria….

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  1. Ecoli Bacteria… remember that 25% of your feces is E coli bacteria….

  2. Plasmids A circular piece of DNA that is not a part of the bacteria’s genome. It is ‘extra-chromosomal.’ Analogy: The Plasmid is the little dog, and the Chromosomal DNA is the big dog. (The cell cannot live without the big dog however…)

  3. Typical Prokaryotic Plasmid:Circular, small, and code for things that are useful to the prokaryote, but notnecessary.

  4. Plasmids give the bacteria extra properties • They can code for toxins • Anthrax toxin is caused by a plasmid • Botulism is caused by a plasmid. • tetanus is caused by a plasmid.

  5. Plasmid’s other properties • They can perform nitrogen-fixation (take nitrogen from the air, and use it.) • Klebsiella pneumoniae • Some plasmids make plants grow tumors • This plasmid is known as a Ti (tumour inducing) plasmid

  6. Antibiotic resistance Plasmids can code for antibiotics • Some bacteria become immune to antibiotics because they have plasmids that make them immune. They can also give their plasmids to other bacteria through transformation. • ampicillin resistance • kanamyicin resistance • chloramphenicol resistance • B-galactosidase resistance • Gentamycin resistance

  7. Another example antibiotic resistance • Note Gonorrhea • 1989 Resistance went from <0.2% to almost 9% in 10 years! • 1999, resistance is reported to be widespread in the US. • 2000 The Centers for Disease Control found resistance to Cipro –our ‘big gun’ and recommended a whole regimen of treatments: 500mg single-dose ciprofloxacin and 400mg ofloxacin as broad-spectrum fluoroquinolones and cephalosporins, respectively, to treat uncomplicated gonorrhea (CDC, 2000). 

  8. How resistance gets transferred. Plasmids get passed through transformation.

  9. Why plasmids are used in genetic engineering • They are easy to put new genes onto: cut the plasmid and the gene you want with the same restriction enzyme…they will ‘match’ and line up… sew them together with ligase enzyme. • Plasmids and bacteria replicate quickly… You get lots of product..

  10. For example: • Cut out a gene like insulin with Ecor I • Cut open pieces of E. coli plasmid with Ecor I. • Mix the new genes and the plasmids together. • The new genes will combine with the plasmids because their ends match. • Add ligase to sew the parts together • Grow a bacterial culture. The bacterial culture will now produce insulin.

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