All of the following statements characterize DNA replication except
All of the following statements characterize DNA replication except
The correct option is B DNA is synthesized in 3' to 5' direction in one strand and 5' to 3' in another.
DNA synthesis always occurs in the 5'-->3' because chain growth results from the formation of a phosphodiester bond between the 3' oxygen of a growing strand and α-phosphate of a dNTP. As we know that the two strands of the parental DNA duplex are antiparallel, and DNA polymerases can add nucleotides to the growing new strands only in the 5'-->3' direction. The leading strand synthesis proceeds continuously from a single RNA primer in the 5'-->3' direction. To facilitate the growth of the lagging strand in the 5'-->3' direction, copying of its template strand must somehow occur in the opposite direction from the movement of the replication fork. This is done by synthesizing a new primer every few hundred bases on the second parental strand. Each of these primers is elongated in the 5'-->3' direction and form discontinuous segments called Okazaki fragments which are later joined together by DNA ligase. DNA replication is bidirectional mechanism because two replication forks are formed at an origin which moves in opposite directions, with both template strands being copied at each fork. Option B is the wrong statement.
DNA synthesis always occurs in the 5'-->3' because chain growth results from the formation of a phosphodiester bond between the 3' oxygen of a growing strand and α-phosphate of a dNTP. As we know that the two strands of the parental DNA duplex are antiparallel, and DNA polymerases can add nucleotides to the growing new strands only in the 5'-->3' direction. The leading strand synthesis proceeds continuously from a single RNA primer in the 5'-->3' direction. To facilitate the growth of the lagging strand in the 5'-->3' direction, copying of its template strand must somehow occur in the opposite direction from the movement of the replication fork. This is done by synthesizing a new primer every few hundred bases on the second parental strand. Each of these primers is elongated in the 5'-->3' direction and form discontinuous segments called Okazaki fragments which are later joined together by DNA ligase. DNA replication is bidirectional mechanism because two replication forks are formed at an origin which moves in opposite directions, with both template strands being copied at each fork. Option B is the wrong statement.
