Question

Find out the number o f base pairs in E. coli DNA if its DNA is 1.36 mm long.

• A. $4\times 10^{6}bp$
• B. $3\times 10^{6}bp$
• C. $2\times 10^{6}bp$
• D. $7\times 10^{6}b$

Answer 1

Answer: (A)

In the given case, the number of base pairs for E. coli would be $4\times 10^6$ bp. It can be calculated as
Average distance between two base pairs of DNA is $3.4\mathring{A}$.
Length of $E$. coli DNA is $=1.36\times 10^7\mathring{A}$
So, number of nucleotides $=\frac{1.36\times 10^7\mathring{A}}{3.4\mathring{A}}=0.39\times 10^7$
$=3.9\times 10^6\cong 4\times 10^{6}bp$