Question

Suppose thymidine labeled with carbon-14 was added to a culture of bacteria and allowed to incubate for 20 minutes (one generation time). The DNA molecules were then isolated from the bacterial cells. If DNA replication is semiconservative, what would you observe about these molecules?

Answer 1

One strand of all the isolated DNA double helices would have C-14 labeled thymidine.

Step-by-step explanation:

DNA replication is a semiconservative process which means that each newly formed DNA double helix contains one parental strand and one newly formed strand.

Since the medium has thymidine labeled with C-14, all the newly formed strands formed during DNA replication would have radio-labeled thymidine.

Therefore, by the end of 20 minutes, one out of two strands on each double helix would have labeled thymidine nucleotides.