Question

if the double stranded dna contains 20% thymine, the % of guanine in dna is what?
a) 30%
b) 10%
c) 90%
d) 40%
..
when I am seeing in the answers it's given (c)90% but how?
Help me with the answer guyz!​

Answer 1

Answer: 30%

Explanation:

To figure out the percentage of guanine, you must first determine the percentage of adenine, which is quite simple: adenine (because it is the complimentary base pair of thymine) is equal to thymine; therefore, there is 20% of adenine as well.

Now to find guanine’s percentage, we initiate Chargaff’s Rule: [A]+[G]=[C]+[T]. Hence, we can deduce the proportion of A:T as 40%, which we then subtract from 100%, leaving us with 60%. Because cytosine and guanine are complimentary base pairs, we now have the answer to the amount of guanine in this DNA sequence: 30%

Check: 30%[C]+30%[G]+20%[A]+20%[T]=100%

P.S. This formula is only applicable to double stranded DNA

Answer 2

Answer:

Explanation:

To figure out the percentage of guanine, you must first determine the percentage of adenine, which is quite simple: adenine (because it is the complimentary base pair of thymine) is equal to thymine; therefore, there is 20% of adenine as well.

Now to find guanine’s percentage, we initiate Chargaff’s Rule: [A]+[G]=[C]+[T]. Hence, we can deduce the proportion of A:T as 40%, which we then subtract from 100%, leaving us with 60%. Because cytosine and guanine are complimentary base pairs, we now have the answer to the amount of guanine in this DNA sequence: 30%

30%