Question

Bacteria were grown in a medium containing heavy isotope of nitrogen (N15) for many generations and all their DNA contained many heavy nitrogen only. A bacterium of this type was transferred to normal medium and allowed to duplicate. After two divisions of heavy DNA is likely to be that [CBSE PMT 1993]
A) Only one daughter cell will have heavy DNA
B) Two daughter cells have normal DNA and other two have both normal and heavy DNA
C) All daughter cells have heavy DNA
D) Half daughter cells have heavy DNA and other half have normal DNA

Answer 1

Bacteria were grown in a medium containing heavy isotope of nitrogen (N15) for many generations and all their DNA contained many heavy nitrogen only. A bacterium of this type was transferred to normal medium and allowed to duplicate. After two divisions of heavy DNA is likely to be that
➡️ Half daughter cells have heavy DNA and other half have normal DNA