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MHT CET Medical202625 April 2026Evening ShiftBiologyMolecular Basis of InheritanceActual

A 340 Å long segment of DNA molecule has 40 thymine nitrogenous bases, what will be the number of guanine bases in the same segment?

Options

  1. A10
  2. B20
  3. C40
  4. D60

Correct answer

D. 60

Step-by-step solution

Length of the DNA segment = 340 Distance between two consecutive base pairs in B-DNA = 3.4 Total number of base pairs = 340 3.4 = 100 Total number of nitrogenous bases = 100 2 = 200 According to Chargaff's rule, A = T and G = C . Given number of thymine bases ( T ) = 40 Number of adenine bases ( A ) = 40 Total number of A and T bases = 40 + 40 = 80 Total number of G and C bases = 200 - 80 = 120 Number of guanine bases ( G ) = 120 2 = 60 Answer: 60

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