BIOMOLECULES AND ENZYMES

BIOLOGY

STRUCTURE OF NUCLEIC ACIDS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In wheat, the relative percentage of the bases Adenine and Cytosine in the DNA is 27% and 23% respectively. What is the likely percentages of Thymine and Guanine in the DNA?
A
Thymine 23%, Guanine 23%
B
Thymine 27%, Guanine 23%
C
Thymine 49%, Guanine 49%
D
Thymine 73%, Guanine 77%
Explanation: 

Detailed explanation-1: -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-2: -Therefore the base percentage of GC is 54% in the whole DNA sequence.

Detailed explanation-3: -The final composition is 22% adenine, 22% thymine, 28% cytosine, and 28% guanine. Uracil is only found in RNA.

Detailed explanation-4: -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%).

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