3. You mix E. coli cells with a 3500 bp plasmid that codes for ampicillin resist

Question

3. You mix E. coli cells with a 3500 bp plasmid that codes for ampicillin resistance and heat shock the mix. You then grow the cells for 20 minutes in liquid media without antibiotic, and make the following series of four dilutions: Dilution 1: 10-fold Dilution 2: 100-fold Dilution 3: 100-folod Dilution 4: 10-fold You then plate 100 ?1 from each dilution onto plates with and without ampicillin hd you see: The plate without ampicillin from dilution #4 gives 58 colonies. The plate with ampicillin from dilution #1 gives 85 colonies.

Explanation / Answer

= 285/1/1/10*100 =0.285

=28.5%

2. 10 microlitre of stock is diluted upto 1000 microlitre = 100 fold dilution

50 ?g/mL × OD260 × dilution factor.= DNA concentration

DNA concentration = 50*0.056*100

= 280 microgram

approx 1 microgram of DNA is required

So the 1/280 =0.0035ml = 0.35 microlitre of DNA will be required. (the stock is 100 fold diluted)

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