Proteins are made of amino acids. These building blocks all contain two identical termini, the amine terminus and the carboxy terminus. But they are distinguished by the functional group "between" the termini, this makes each protein. Proteins are the machinery of life, some examples are: helicase, a protein that unwinds DNA to prepare it for replication, Kinases are proteins that phosphorylate other proteins, primase is a protein that places primers on single strands of DNA so that another protein can bind and synthesize new DNA.