Question

2.

if' a double stranded DNA has 20 per cent of cytosine,
calculate the percentage
of adenine in the DNA.
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Answer 1

According to Chargaff’s rule all cellular DNAs, regardless of the species, number of adenosine residues is equal to number of thymidine residues which means that A=T; and the number of guanosine residues is equal to the number of cytidine residues; G= C. If there is 20% cytosine which means guanine percentage is also 20%.

Thus, the percent of A+T= 100-(G+C)

A+T = 100-40 = 60,

Adenine percent= 60/2= 30.

adenine percentage = 30%

hope it helps you :)

Answer 2

It is your answer here

Thus, if a double-stranded DNA has 20% cytosine, it has 20% guanine. Thus, C + G makes 40% of the total bases. The remaining 60% includes both adenine and thymine which are in equal amounts. So, the percentage of adenine is 30%