The backbone of the DNA molecule is made of a repeated pattern containing a sugar called deoxyribose and a phosphate group. The backbone is spatially arranged in the form of a double helix, with base pairs connecting the two sugar-phosphate strands.
The DNA molecule acts as an information storage medium for the cell. Information is stored in the sequence of four bases: adenine, guanine, cytosine and thymine. A base, a molecule of sugar and a phosphate group form a functional group called a nucleotide, which is a unit block for the molecule of DNA. DNA molecules are usually found in the cell nucleus; however, a smaller quantity is also found in the mitochondria.