Botany-DNA Structure
NEET Botany DNA Structure MCQ Question
Type: MCQ-numerical-Easy-Class 12
If the length of the DNA double helix in a typical mammalian cell is approximately 2.2 meters, and the length of E. coli DNA is 1.36 mm, what is the approximate ratio of the number of base pairs in a mammalian cell to that in E. coli?
A
1600:1
B
2200:1
C
1700:1
D
2000:1
Correct Answer
Option A
Detailed Explanation
The mammalian DNA length is 2.2 meters = 2200 mm. E. coli DNA is 1.36 mm long. Since the distance between consecutive base pairs is 0.34 nm (or 0.34 x 10^-6 mm), the number of base pairs is proportional to the length of the DNA. The ratio is therefore 2200 mm / 1.36 mm = approximately 1618:1, which rounds to 1600:1.
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