Chemical Bonding, DNA, & Hydrogen Bonds

Here's a link to an excellent short video summing up different kinds of chemical bonds, including the hydrogen bonds between opposing base pairs that hold together the two complementary strands of the double helix: 

Chemical Bonds

Below is a visual of the hydrogen bonds between 2 pairs of nucleotides on adjacent strands of DNA. Note that both of the molecules must be polar (have an unequal charge on two sides of the molecule, thus having positively and negatively charged sides, like water) to have the weak bonding interaction with hydrogen atoms that is the hallmark of a hydrogen bond:

Water molecules are held together by hydrogen bonds.