DNA is made up of sugar phosphate and the four bases, thymine, cytosine, adenine, and guanine. The bases are always connected in pairs with thymine connecting to adenine, and cytosine connecting with guanine. It is the sequence of these bases within the DNA that make us each different, DNA holds informations so that our cells know what to do and with this information they can make the proteins that are necessary for life. A large number of the human genes are similar between us as they are necessary for us to function properly, what makes us different from one another are the 1% of genes called alleles. These give us each our own unique, physical characteristics that can change things from eye colour to our hair. These can be inherited from our parents as well. DNA is the building blocks of life as it is what gives our cells a purpose, it contains the information that we need to survive.