DNA is a polymer composed of 2 polynucleotide chains joined together by hydrogen bonds
A-T is joined by 2 hydrogen bonds
C-G is joined by 3hydrogen bonds
The polynucleotide chains run antiparallel to each other
The sugar-phosphate backbone is on the outside of the molecule
DNA molecules are very long and thin, and are tightly coiled within the chromosome
At one end of a sugar-phosphate backbone is carbon atom number 5 (C5) of a sugar unit. This is the 5' end of the molecule, and at the other end is 3' (C3)
How is DNA suited to its function?
-it is a very stable molecule and its informationcontent passes essentially unchanged from generation to generation
-it is a very large molecule and carries a large amount of geneticinformation
-the two strands are able to separate, as they are held together by hydrogenbonds
-as the basepairs are inside the helix, the geneticinformation is protected
