Question

14. You inoculated a 1 mL tube of sterile LB broth with E. coli, and let it grow @37C overnight. The next day you extracted a total of 2.15 ug of DNA from this culture. Calculate how many cells were in that 1 mL of culture? (Hint: Use the value derived above to do this calculation). 5 points 15. If you assume that your 2.15 ug of DNA isolated from E. coli had an average length of 10,000 bp, approximately how many fragments are in your sample? (Hint: consult DNA Fact Sheet on Canvas for conversion factors that might be useful here). Show all calculations. Write answer below. (5 points).

Answer 1

Answer 14. As per given data 2.15 microgram of DNA is extracted which means 2.15 X10^-6 grams. Average molecular weight of DNA base pair is 650 dalton and one dalton equals to 1.67X10^-24 grams. Then 650 X 1.67X10^-24 = 1086 X10^-24 or  

Then 2.15 X10^-6 grams / 1.09 X10^-22 grams = 1.97 X10¹⁶ cells. Hence the number of cell in 1 ml of culture is 1.97 X10¹⁶ cells.

Answer 15 if E.coli has length of 10,000 bases then fragments presents are 1.97 X10¹⁶ . because there are approx 1.97 X10¹⁶ cells which means each cell have individual genome which is considered as different fragment. So 1.97 X10¹⁶ fragments will be there.