Mode of DNA replication in Escherichia coli is
Conservative and unidirectional
Semiconservative and unidirectional
Conservative and bidirectional
Semiconservative and bidirectional
The correct option is D Semiconservative and bidirectional
DNA replication is bidirectional mechanism in E. coli because two replication forks are formed at origin which moves in opposite directions, with both template strands being copied at each fork. If it was unidirectional, the replication fork would move in single direction only. This makes options A and B incorrect. In E. coli, the parental DNA strand serves as a template for the synthesis of a new strand and produces two new DNA molecules, each with one new strand and one parental strand; thus it is the semiconservative mechanism of DNA replication. In the conservative mode of DNA replication, new DNA molecules have both newly synthesized DNA strands while the parental DNA regains its duplex nature with both original strands. This makes options A and C incorrect. The correct answer is D. DNA replication is semi-conservative and bidirectional in E. coli.