Question

.  Spongebob extracts some DNA from Patrick, measures the base composition, and finds it contains 21% guanine.

            Calculate the percent of the other three bases in starfish DNA. Show your math.

Answer 1

Ans:

According to the base pair rules or the Chargaff's rules, the ration of purine bases ( cytosine and thymine) and the pyrimidine bases (guanine and adenine) in the DNA is 1:1.That is, whatever the amount of guanine will be, the same amount of cytosine will also be present in the DNA.In the same way,the amount of adenine will be equal to that of thymine.

Now, In the given question, the amount of guanine in the DNA is 21%.Therefore,the amount of cytosine will also be 21%. Thus, applying the Chargaff's rule, the remaining 58% will be that of adenine and thymine, that is 29% adenine and 29% thymine.

Hence, the answer is

Cytosine = 21%

Adenine = 29%

Thymine = 29%