A fragment of a DNA molecule contains 440 guanyl nucleotides, which is 22% of the total.

| February 6, 2021 | education

A fragment of a DNA molecule contains 440 guanyl nucleotides, which is 22% of the total. Determine the content of the remaining nucleotides and the length of this fragment.

According to the principle of complementarity in DNA, the number of nucleotides G is equal to the number C, and the number A is equal to the number T.
If in DNA n (G) = 440, then n (C) = 440. Hence, n (G + C) = 880 and this will be 44%, then n (A + T) will be 56%.
We make the proportion: 880 / x = 44/56, x = 880 * 56/44 = 1120. So, n (A + T) = 1120, therefore n (A) = n (T) = 560.
In total, this DNA contains nucleotides: 880 + 1120 = 2000.
The length of one nucleotide is 0.34 angstroms. It must be remembered that a DNA molecule consists of 2 strands. If there are 2000 nucleotides in total, then there are 1000 in each of the chains, then the length of the DNA will be equal to: 0.34 * 1000 = 340 angstroms.



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