Question

In a 3.2 Kbp long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases?

• A. 780
• B. 1560
• C. 740
• D. 1480

Answer 1

Answer: (A)

In the given piece of DNA, The total number of bases adenine, thymine, cytosine and guanine is $3.2Kbp$ which is equal to 3200 base pairs.
i.e., $A+T+C+G=3200$
or, $(A+T)+(C+G)=3200$
or, $2A+2C=3200$ since bp of $A=T$ and $C=G$
or, $A+C=1600$
or, $C=1600-A=1600-820$
or, $C=780$
So, the number of cytosines will be 780 bps.
Explanation of the incorrect option:
Option B: the number of cytosines will be $780bps$.
Option C: the number of cytosines will be 780 bps.
Option D: the number of cytosines will be 780 bps.
Final answer: In a $3.2Kbp$ long piece of DNA, 820 adenine bases were found.
The number of cytosine bases is 780 .