Question

genetic code
warm-up active
what similarities do you see in the dna bases?
in a single organism, what do you notice about the
relative proportions of dna bases?
a and t occur in similar proportions.
t and g occur in similar proportions.
a and c occur in similar proportions.
g and c occur in similar proportions.
retry
intro done

Explanation:

Looking at the data for each organism:

• For Human: \(A = 30.9\), \(T=29.4\) (close), \(G = 19.9\), \(C=19.8\) (close)
• For Chicken: \(A = 28.8\), \(T = 29.2\) (close), \(G=20.5\), \(C = 21.5\) (close)
• For Grasshopper: \(A=29.3\), \(T = 29.3\) (equal), \(G = 20.5\), \(C=20.7\) (close)
• For Sea urchin: \(A=32.8\), \(T=32.1\) (close), \(G = 17.7\), \(C=17.3\) (close)
• For Wheat: \(A=27.3\), \(T=27.1\) (close), \(G=22.7\), \(C=22.8\) (close)
• For Yeast: \(A=31.3\), \(T=32.9\) (close), \(G=18.7\), \(C=17.1\) (close)
• For \(E - coli\): \(A=24.7\), \(T=23.6\) (close), \(G=26.0\), \(C=25.7\) (close)

We can observe that for each organism, the proportion of \(A\) (adenine) is similar to \(T\) (thymine) and the proportion of \(G\) (guanine) is similar to \(C\) (cytosine). This is in line with Chargaff's rules which state that in DNA, \(A=T\) and \(G = C\) (in terms of molar ratios).

Answer:

A and T occur in similar proportions. G and C occur in similar proportions.