A single strand of DNA helix consists of 100 nitrogenous base pairs. If 36 of the bases are adenine and 24 are cytosine, how many should be thymine on the complementary strand?
A. 36 guanine
B. 36 thymine
C. 40 guanine
D. 40 thymine
Answer (3)
It is stated int The Chargaff’s rule that DNA from any cell of organisms must have the ratio 1:1, following the base pair rule that: A=T G=C Where, A is adenine, T is thymine, G is guanine and C is cytosine.
So we have; 36 Adenine = 36 Thymine 24 Cytosine = 24 Guanine The answer to this item then is 36 thymine.
To answer this can be achieved by using Cargaffs rule. This rule states A bases equal the amount of T bases and the amount of C base equals the amount of G bases. This rule came to be dye to the base pairing found in DNA and RNA. Since there are 36 bases of adenine then there are 36 bases of thymine. Additionally since there are 24 bases of cytosine there are 24 bases of guanine.
The number of thymine bases on the complementary DNA strand is 36, as determined by Chargaff's rules which state that adenine pairs with thymine in a 1:1 ratio. The correct answer is B. 36 thymine.
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