Bacteria Characteristics of Bacteria | Reproduction of Bacteria.
Bacteria
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Transcript of Bacteria
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Bacteria
Bacteria – single-celled organisms that are prokaryotic (no true nucleus)
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BacteriaBacteria are often used
in Biotech to study genes.
Simple to grow
Grow rapidly
24 hours
370C
Why use bacteria?
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BacteriaTo grow bacteria, need:
1.Correct nutrients – LB agar (solid) or LB broth (liquid).
2. Correct temperature – 370C.
3. Can divide every 20 minutes.
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Transformation
Changing an organism’s traits by adding a new gene.
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Why transform bacteria?
Study genes of complex organisms in much simpler ones.
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Ways to get DNA into a cell:Electroporation
Using electricity to poke holes in cell membrane; DNA rushes into cell.
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Ways to get DNA into a cell:Virus Infection
- Replace “disease” genes with “healthy” genes.
- Virus “infects” cell with new gene.
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Ways to get DNA into a cell:Gene Gun
- DNA attached to gold pellet.
- Pellet fired into cell.
- Typically used with plants. Why?
Gene Gun Animation
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Ways to get DNA into a cell:Heat Shock
Using heat to open pores in cell membrane. (see sketch on board).
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Transformation Efficiency
# of bacterial cells on plate# bacterial cells possible on plate
For heat shock, this number is <0.01% (plate hold about 1 million colonies)
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How do you know which cells have been transformed?
Selectable marker – gene which allows only transformed cells to survive.
Ex. Antibiotic resistance genes
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What DNA will we transform into cells?
Plasmid – small, circular DNA
small “easy” to get into cells
familiar genes will be used to make proteins
vector can carry other genes into bacteria
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What DNA will we transform into cells?
pVIB
luciferase – gene encoding Bioluminescence video
ampr = ampicillin-resistance gene
Any bacteria with this gene can grow in presence of ampicillin (antibiotic)
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What DNA will we transform into cells?
pGREEN
GFP –
GreenFluorescentProtein
Also ampr
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What type of bacterial cells are we going to transform?
E. Coli that are “competent”.
Competent – ready to be transformed.
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How are we going to make competent cells?
Treat cells with CaCl2
In solution CaCl2 Ca2+ + 2 Cl-
Positively charged Ca2+ coats negatively charged pores. DNA can move into cell.Heat Shock Animation