Biology Question on the molecular basis of inheritance

Question

In a 3.2 Kbp long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases?

Answer 1

Solution

One Kbp of DNA contains 1000 base pairs. So the total number of base pairs in $3.2 kbp$ is (3.2X1000) $3200 bp$ . Out of which 820 base pairs are adenine so the number of thymine will also be 820 as number of adenine is equal to thymine according to chargoffs rule. A total number of cytosine $+$ guanosine will be $3200-780 X 2=1560$ . As the number of cytosine is equal to guanine so cytosine bases in the DNA can be calculated as $1560 / 2=780$ .