What is DNA?

Your body is made up of billions of tiny cells, working all the time to stay alive by fulfilling different jobs. Each job is done by several small molecules, called proteins. All of the proteins that the cell needs are “coded” by DNA, a long molecule found in the center of each cell.

DNA is made up four different bases, or letters, A, T, C, and G, repeated in a random order. A strand of DNA consists of 3.3 billion bases. To put it in perspective, that many letters would take up 3 gigabytes of storage space in a computer. Through a complex process, some small sequences of letters can be converted into a functional protein. These portions of DNA are called genes. Humans have approximately 20,000 genes scattered throughout the genome.

The DNA in each of your cells have the exact same sequence of bases. The DNA sequence of any two humans is 99.9% identical, meaning that some bases are changed. For example, where one person may have the base ‘A’ at a certain part of the sequence, another may have the base ‘T’ or ‘C’ or ‘G’ in the same spot. This 0.1% difference accounts for 3 million bases, and the small differences are called variants.

Variation in a single base is called a Single Nucleotide Polymorphism, better known as a SNP (pronounced “snip”). Depending on the base at that position, the resulting protein may have a slightly different structure which changes how well it does its job.



DNA molecule

Your body is made up of billions of cells, each cell containing an identical long DNA molecule.


DNA is made up of four ‘letters’ or molecules, commonly referred to as bases: Adenine, Thymine, Cytosine, Guanine (ATCG).

The genome

These four different molecules bind together in a double-helix form and create a long sequence. Each strand of DNA is made up of 3 billion bases, and the entirety of this is called the genome.

Your genes

As you may know, DNA contains all of your genes. Genes are sections of the large DNA sequence that is used to create the building blocks of your body.

The role of proteins

These building blocks are proteins. Proteins create, regulate, and make up all of the cells, tissues, muscles and organs in your body.