Question

1. The bacterium E. Coli is a Gram-negative rod that is 1mM  x 2mM.   Each E. Coli cell contains a chromosome of 4 x 10⁶bp of double-stranded DNA.  Since 1 kilobase pair (kbp) of double-stranded DNA is 0.340mM in length, what is the length of the E. Coli chromosome? (1 kbp = 1000 base pairs, and 1mM = 10^-6meters).   
2. A single colony-forming unit (CFU) of E. coli contains 10⁹ cells.  If you were to join all the E. coli chromosomes contained in that colony together into one gigantic chromosome, how long would it be? Express your answer in miles (1 meter = 6.2 x 10^-4mile)

need help with part B!

Answer 1

length of chromosome in basepairs=4 10^6 basepairs.

length of 1000 bp=0.34 mm

so length of 1 bp= 0.34/1000 mm

length of 4 10^6 basepairs.=4 10^6 (0.34/1000)= 1360 mm

length of chromosomes in 109 cells= length of chromosome in one cell 109=1360 10^9=1.3610^12 mm

1 mm=10^-3 m

so 1.3610^12 mm=1.36 10^1210^-3=1.3610^9 m.

1 meter = 6.2 x 10^-4mile

so

1.3610^9 m=1.3610^9 6.210^-4= 843200 miles

so the answer is 843200 miles