DNA replication - DNA replication DNA helicase unwinds the...

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DNA replication DNA helicase unwinds the DNA molecule by breaking hydrogen bonds. The area in a DNA molecule where unwinding is occurring is called a replication fork . In the diagram, it looks like an upside-down Y. RNA primase adds an RNA primer. The direction of synthesis is from 5’ to 3’. The red color represents RNA.
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The enzyme that will synthesize new DNA is called DNA polymerase . It cannot initiate a new strand, it can only elongate a strand that is already present. Synthesis of new DNA therefore cannot begin until a short strand of nucleotides is added. This short strand is called a primer. Primase creates an RNA primer and then DNA polymerase lengthens this strand by adding DNA nucleotides. The RNA primer will later be removed and replaced by DNA. DNA polymerase III lengthens the strand that is being synthesized by adding nucleotides that are complimentary to those on the template strand (A paired with T and G paired with C). The arrows indicate the direction of synthesis: 5' to 3'.
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DNA replication - DNA replication DNA helicase unwinds the...

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