Multiple choice

An actively dividing culture of E. coli with radioactive THYMINE; daughter cells would have

  1. one daughter cell radioactive, not the other

  2. DNA in both daughter cells would be radioactive

  3. neither of the daughter cells would be radioactive

  4. all four bases of the DNA would be radioactive

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA replication is semi-conservative. Each daughter cell receives one original strand and one newly synthesized strand. Since the thymine in the medium is radioactive, the new strands in both daughter cells will incorporate it, making both cells radioactive.