Bacteria are grown in ¹⁵N (heavy)medium and then transferred to ¹⁴N (light)medium and are allowed to replicate for 2 generations.The DNA is subsequently isolated and centrifuged in a CsCl₂ gradient to yield what type of gradient band(s)?

Question

Quizplus · Accepted Answer

When bacteria are grown in a heavy medium and then transferred to a light medium, the first generation of DNA replication produces molecules with one heavy and one light strand (half-heavy). After the second generation in the light medium, there will be both light DNA (from the replication of half-heavy DNA) and half-heavy DNA (from the replication of any remaining heavy DNA). Thus, the gradient will show one light band and one half-heavy band.

Bacteria Are Grown in 15N (Heavy)medium and Then Transferred to 14N

Bacteria Are Grown in ¹⁵N (Heavy)medium and Then Transferred to ¹⁴N