3.16

3.16 describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G)

There are thousands of genesà expand: HELIX à ATGC holding two strands together

The two sugar phosphate backbones are parallel. What hold the two strands together are the bases (adenine, thymine, cytosine and guanine). They hold the helices together by pairing between A & T and G & C.

Looking at the picture on the very right, we can see that the order is ACTGAACCAG. This is the order of bases.

Genes are determined by the order and number of bases, which lead to construction of protein in the cytoplasm into determining characteristics.