describe the structure of a DNA molecule as a double helix, including: • the importance of complementary base pairing between the 5’ to 3’ strand and the 3’ to 5’ strand (antiparallel strands) • differences in hydrogen bonding between C–G and A–T base pairs • linking of nucleotides by phosphodiester bonds

state that a gene mutation is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide