If 20% of the DNA is adenine, what percent is guanine?

If 20% of the DNA is adenine, what percent is guanine?

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Answer

• Answer = 30%
  Guanine will be 30%
  Explanation:
  If 20% of the DNA is adenine, what percent is guanine?
  According to chargaff’s rule, DNA has equal number of guanine and cytosine, and an equal number of adenine and Thymine
  Adenine pairs with Thymine, so if Adenine is 20%, even Thymine will be 20%.
  Since DNA has four bases (A, T, G, C), if A and T occupies (20% + 20%) 40% of the DNA, then the remaining percentage (100% – 40%) is occupied by Guanine and Cytosine.
  Ratio of G to C is 1:1
  Percentage of G and C combined is 60%
  Therefore, 60% / 2 = 30% would be Guanine
  Guanine occupies 30%