A bacterium with completely non-radioactive DNA was allowed to replicate in a radioactive medium for three generation what % of the bacteria should contain radioactive DNA?

  1. 25%
  2. 75%
  3. 0%
  4. 100%

1 Answer
Vijay Raghavendran
Mar 7, 2018

None.

Explanation:

First generation:
Bacteria0nr -> Bacterial1r + Bacterial2nr
nr stands for non-radioactive.
a mother cell splits into two daughter cell. Daughter's DNA will be synthesized from the medium components that are radio-active.

Second generation:
Bacterial1r -> Bacterial2r + Bacterial2r
Bacterial2nr-> Bacterial2r + Bacterial2nr
the non-radioactive DNA acts as a template for the new dna to be synthesised.

Third generation:
Bacterial2r -> Bacterial3r + Bacterial3r
Bacterial2r-> Bacterial3r + Bacterial3r
Bacterial2r -> Bacterial3r + Bacterial3r
Bacterial2nr-> Bacterial3nr + Bacterial3r

Thus in the third generation 7 out of 8 cells will be radioactive or 87.5%. This option is not available in your answer list.

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