Question
Biology Question on the molecular basis of inheritance
The following ratio is generally constant for a species
A
A + G / C + T
B
T + C / G + A
C
G + C / A + T
D
A + C / T + G
Answer
G + C / A + T
Explanation
Solution
According to Chargaff (1950) rules, purines and pyrimidines occur in equal amounts. The amount of adenine is equal to that of thymine and cytosine is equal to that of guanine (A = T and G = C). However the amount of A or T is not equal to G or C. It means A + T/G + C is variable. It is 1.52 in human beings and 0.97 in E.coli. In other words G + C/A + T is constant for a particular species.