Question

The percentage of thymine (T) in a given segment of double-stranded DNA is 36\%36%36, percent.

What are the percentages of the remaining nucleotides?
Choose 1 answer:
Choose 1 answer:

(Choice A)
A
14 \% \text{ A} 14% A14, percent, start text, space, A, end text, 36 \% \text{ C} 36% C36, percent, start text, space, C, end text, and 14 \% \text{ G} 14% G14, percent, start text, space, G, end text

(Choice B)
B
14\% \text{ A}14% A14, percent, start text, space, A, end text, 14 \%\text{ C} 14% C14, percent, start text, space, C, end text, and 36 \% \text{ G} 36% G36, percent, start text, space, G, end text

(Choice C)
C
36 \%\text{ A} 36% A36, percent, start text, space, A, end text, 14 \%\text{ C} 14% C14, percent, start text, space, C, end text and 14 \%\text{ G} 14% G14, percent, start text, space, G, end text

(Choice D)
D
14 \% \text{ U}14% U14, percent, start text, space, U, end text, 14 \% \text{ C} 14% C14, percent, start text, space, C, end text, and 36 \% \text{ G}36% G36, percent, start text, space, G, end text

Answer 1

Option C is correct

Guanine-14%, Cytosine-14%, Adenine-36%

Step-by-step explanation:

A DNA molecule consists of two long polynucleotide chains, each called strands. Hence, a DNA molecule is double-stranded. According to Chargaff, who postulated the complementary base pairing rule, the amount of Adenine nucleotide should be equal Thymine while the amount of Guanine equal Cytosine in a DNA molecule. In other words, the rule is saying that the amount of purine bases (Adenine and Guanine) and pyrimidine bases (Thymine and Cytosine) should be in 1:1 ratio.

Based on this, in a DNA molecule, the percentage content of Adenine is equal that of Thymine while that of Guanine equal Cytosine i.e. A=T, G=C.

Also, all together, the amount the four nucleotides equals 100%.

In a DNA strand with 36% Thymine, this automatically means the percentage content of Adenine, its complementary pair is also 36%.

We now have, A + T = 36 + 36 = 72%

We are left with Guanine and Cytosine nucleotides.

Since, A+T+G+C= 100

72+G+C= 100

G+C= 100-72

G+C= 28

Hence, the amount of Guanine and Cytosine in the DNA is collectively 28%. To get the individual percentage, we divide 28% by 2.

We have, Guanine (14%) = Cytosine (14%).

Therefore, the percentages of the four nucleotides are:

Adenine-36%

Thymine-36%

Guanine-14%

Cytosine-14%