Within
bacterial cells, a singular circular DNA molecule assumes a pivotal role,
necessitating replication prior to cell division. Notably, certain circular DNA
configurations dictate a unidirectional replication pattern. In this intricate
dance of genetic duplication, bacteria employ a trio of DNA polymerases - I,
II, and III.
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| DNA Bubbles |
DNA
polymerase I, although modest in size, emerges as a critical participant in the
orchestration of DNA replication. While its primary role is supportive, it
contributes significantly to the process. A distinctive protagonist in E.
coli's replication saga, polymerase III, exists as a dimeric entity, steering
the replication of a solitary DNA strand. Its remarkable swiftness is evident
as it deftly guides the DNA through the enzyme complex, hurtling forward at an
astonishing velocity of approximately 1000 nucleotides per second.
Polymerase
II, another character in this molecular narrative, possesses an intriguing
characteristic - it exclusively appends nucleotides to an existing chain that
has already engaged with the parent strands. The tale of replication unfolds
diversely as some DNA molecules initiate replication at the origin and traverse
in opposing directions. Throughout these intricate molecular maneuvers, a
steadfast rule reigns: the process unfailingly advances in the 5' to 3'
direction, a cardinal principle governing the DNA replication symphony.
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