What is rolling circle replication? How does it differ from bidirectional replication?
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In bidirectional replication the DNA is replicated in both directions from the point of origin. The DNA unwinds in both directions from the point of origin and is replicated. See this picture for a visual:
http://www.mun.ca/biology/scarr/iGen3_03…
In rolling circle replication the DNA is in a circular formation. Instead of both strands being a template strand, only one strand is. The outer strand in the circle gets cut, which frees a 3' OH group on the template inner strand so that a new DNA strand can be made around the outer circle. As this is happening the original outer strand is being displaced [it is being dissociated from the inner strand] and eventually leaves. In this method of replication, replication only occurs in one direction!
http://www.mun.ca/biology/scarr/iGen3_03…
In rolling circle replication the DNA is in a circular formation. Instead of both strands being a template strand, only one strand is. The outer strand in the circle gets cut, which frees a 3' OH group on the template inner strand so that a new DNA strand can be made around the outer circle. As this is happening the original outer strand is being displaced [it is being dissociated from the inner strand] and eventually leaves. In this method of replication, replication only occurs in one direction!