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Question: Answered & Verified by Expert
In a $3.2 \mathrm{Kbp}$ long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases?
BiologyMolecular Basis of InheritanceAIIMSAIIMS 2016
Options:
  • A $780$
  • B $1560$
  • C $740$
  • D $1480$
Solution:
1897 Upvotes Verified Answer
The correct answer is: $780$
Total DNA $=3.2 \mathrm{Kbp}=3200 \mathrm{bp}$
Adenine $=820$
According to Chargaff's rule
$[\mathrm{A}]=[\mathrm{T}],[\mathrm{G}]=[\mathrm{C}]$
So, Thymine $=820$
Therefore, total $\mathrm{A}+\mathrm{T}$ content $=820+820=1640$
Also, $A+T=3200-(G+C)$
So, $\mathrm{G}+\mathrm{C}$ content $=3200-1640=1560$
So, cytosine $=\frac{1560}{2}=780$

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