Question

A double stranded DNA has 20 coils with 60 nucleotides of Adenine. Find out the number of cytosine bases?
Options:
1. 140 nucleotides
2. 70 nucleotides
3. 280 nucleotides
4. 35 nucleotides

Answer 1

Answer:

140 nucleotides

Explanation:

Total base pairs - 20 × 10 = 200bp

Adenine = 60 nucleotides

Thynine = 60 nucleotides

so, A = T = 60bp

∴ G ≡ C = (200 - 60) bp = 140bp

Cytosine = 140 nucleotides

Answer 2

Answer:

Only the 1st option - 140 nucleotides would be the accurate answer

Explanation:

Any Double-stranded coil of DNA would consist of 10 bp with 4 average bases  

Here, we have 20 coils of dsDNA, Hence -

= 20 x 10 = 200 bp

Then, as per Chargaff’s rule, any actual DNA molecule should have a similar ratio of pyrimidine (cytosine and thymine) and purine bases (adenine and guanine) which indicates that the amount of specific adenine molecules is equal to the specific thymine molecules as well and that will also apply on these two bases where the exact amount of guanine molecules is similar to cytosine molecules, which is % A = % T and % G = % C

So, for now, we have nucleotides of Adenine = 60 which their amount would be similar to thymine of course. i.e A = T

Now, when we calculate the G=C = 200 - 60 = 140

Therefore, the no. of cytosine bases will be 140 which would be equal to the guanine bases as well.

Learn more about identifying the specific dsDNA bases -

https://byjus.com/question-answer/if-a-double-stranded-dna-has-20-of-cytosine-what-will-be-the-percentage-of/