DNA Replication                                                               >>Back to Notes>>
More primers hybridize to the opposite strand of DNA.  Pol III starts elongating 5' to 3' but it keeps running into the back of an RNA primer.  This is the lagging strand.  There are TWO lagging strands (why?)

(Note: Recent experiments show that Pol III is actually a dimer that synthesizes both the leading and lagging strands simultaneously.  You don't need to know this for the test, but if you're interested here's how we drew it on the blackboard for BIOL 363 class!)