26 PROCESS OF DNA REPLICATION Step One: Unwinding DNA Unwinds to form a region of single stranded DNA Unwinding controlled by enzyme called DNA helicase Occurs at many points along the DNA Step Two: Copying Short RNA Primers attach to the open strands and initiate replication Each 'open' strand acts as a template for a new DNA strand Leading strand is formed one nucleotide at a time; Individual DNA nucleotides are added at the 3' end according to base pairing rules DNA polymerase is responsible for catalysing this reaction Lagging strand formedby fragments (chuncks) aided by enzyme DNA Ligase Result   Each new copy of DNA is an exact copy of the original   Each newdouble stranded molecule contains one of the original DNA strands and one new DNA strand (semi conservative) Biozone: 207 - 208 Quick Check 18 & 19
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