Give an example in the human body of a molecule cotaining ionic bonds

An ionic bond is a complete transfer of electrons from one atom to another. This generally happens between atoms that have opposite electronegativity. This means one has very few atoms in their outer shell, while the other has many. A common example of an ionic bond is that of salt, with Na and Cl. Sodium has one electron in its outer shell, in which it transfers to chloride to make an ionic bond.

Ionic bonds are usually found in dry forms such as salts and are found in compounds throughout the human body. Ionic compounds are generally water soluble.
DNA - As you recall, DNA is formed in the shape of a double helix. The double strands of DNA are held together by hydrogen bonds. Each single strand has a backbone made of sugar and phosphate, as well as either a purine (adenine or guanine) or pyrimidine (cytosine or thymine). Each purine is connected to a pyrimidine through a hydrogen bond, giving the double DNA strand strength, and flexibility. This bond holds the two sides of DNA together, each bond contributing to the overall strength of DNA. When DNA is replicated, special enzymes known as DNA helicase "unzip" DNA and these bonds are broken so the two strands can be individually replicated.