Alleles are created by mutations and replication errors, they can be neutral eg. left handed, positive eg. faster, or negative eg. no head.
Helicase undos (unzips) the DNA double helix and DNA prylimaries build two new double helixes using the two halves of the original. Proteins then attach themselves to the structure and bind it all together.
Summary: DNA replications is the first place mutation occurs. Mutations can the produce new alleles
S - statement
E - explain
E – evidence/examples
D – discuss –other points of view and contrary evidence, 2 paragraphs