Question

starting with 15n15n (heavy) dna, and after one generation in the 14n medium, e. coli cells subjected to density - gradient centrifugation will produce single band of dna with medium density. true or false

Explanation:

DNA replication is semi - conservative. When heavy DNA ($^{15}$N$^{15}$N) replicates in a $^{14}$N medium for one generation, each new DNA molecule consists of one heavy strand ($^{15}$N) and one light strand ($^{14}$N). Density - gradient centrifugation will show a single band of intermediate density DNA.

Answer:

True