Question

Bacteria are grown in 15N (heavy) medium and then transferred to 14N (light) medium and are allowed to replicate for 1 generation. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of gradient band(s)?

Answer 1

Answer:

The intermediate density band is observed.

Explanation:

Messelson and Sthal's explained the model of  semi conservative nature of DNA replication. According to this model, the newly synthesized DNA molecule contains one newly synthesized strand and one parental strand.

Firstly, bacteria grown in 15N media is transferred to 14N media. The isolated DNA is centrifuged and intermediate density DNA  band is observed that contains one strand of 15N (parental strand) and one strand of 14N (newly synthesized strand).