- DNA helix video 1: Two different kinds of bonds: covalent (strong) and hydrogen (weak)
- DNA helix video 2: Two different kinds of hydrogen-bonding basepairs: C-G vs A-T
- DNA helix video 3: Orientation of the covalent versus hydrogen bonds
- DNA helix video 4: Add directionality to the strands (to make antiparallel)

DNA helix video 1: Two different kinds of bonds: covalent (strong) and hydrogen (weak)

DNA helix video 2: Two different kinds of hydrogen-bonding basepairs: C-G vs A-T

DNA helix video 3: Orientation of the covalent versus hydrogen bonds

DNA helix video 4: Add directionality to the strands (to make antiparallel)