THE MOLECULAR BASIS OF INHERITANCE
STRUCTURE OF NUCLEIC ACIDS
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Thymine 23%, Guanine 23%
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Thymine 27%, Guanine 23%
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Thymine 49%, Guanine 49%
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Thymine 73%, Guanine 77%
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Detailed explanation-1: -Therefore the base percentage of GC is 54% in the whole DNA sequence.
Detailed explanation-2: -Therefore, given 27 percent of thymine, there is also 27 percent of adenine. Thus, the amount of guanine and cytosine would have 100-27(2)= 46, which follows that there is 23 percent of cytosine (46/2).
Detailed explanation-3: -Erwin Chargaff first noticed that the percentage of adenine and thymine, as well as guanine and cytosine, is almost the same in every DNA molecule. This is known as the Chargaff’s rule. If A = 25%, we can conclude that T = 25%. The remaining 50% (100-25-25) of the DNA is composed out of guanine and cytosine (G+C=50%).
Detailed explanation-4: -The correct answer: A DNA molecule with 24% guanine would have 26% adenine.