Simply put, biochemists study the molecules of life. The discipline grew out of a combination of organic chemistry and biology, as scientists in both of these fields became more aware of the importance of the chemical processes taking place within organisms.
Organic chemistry is devoted to studying the structure and function of compounds composed primarily of hydrogen, oxygen, and carbon. Certain combinations of these elements take the form of fats (lipids), sugars, and amino acids (the building blocks of proteins, enzymes, and super-molecules like RNA and DNA). Molecular biologists study these compounds in order to gain a better appreciation of the way that plants and animals are formed, utilize nourishment, grow and diversify, reproduce, and decay. Biochemists apply various analytical techniques to discern the structure and reactive mechanisms of these compounds.
One of the great triumphs of biochemistry was the discovery of the double helix structure of DNA (deoxyribonucleic acid). Scientists knew that the molecule was composed of amino acids (a special class of organic compounds containing nitrogen) and sugars, but it took a great deal of theoretical and experimental work before Watson and Crick were finally able to determine that the DNA molecule actually resembled a spiral staircase, with the sugars on the outside and an inner set of joining steps made up of specific pairs of amino acids. The structure and composition of DNA is the same in all living organisms. It is only the overall length and the peculiarities of the arrangement of amino acids that change from plant to plant and animal to animal. Because the amino acids combine in accordance with very specific rules, each organism displays a characteristic DNA code which is passed on from generation to generation. Small changes among different individuals can be detected by comparing their DNA sequences with those of other members of their species and their family.
So-called genetic fingerprinting, which uses DNA to identify specific individuals is possible because biochemists have learned the rules by which DNA operates. Even the smallest sample of tissue can be used to reconstruct the DNA of an individual, thanks to the work of Kerry Mullis, who developed a process known as PCR (polymerase chain reaction) which is used to rapidly multiply the available amount of DNA from the molecular pattern in a given sample. With the extended sample, biochemists can easily decode the DNA sequence, helping to determine the probability that a particular individual does or does not match a sample from a database of potential people. This test can be used to determine paternity and it is becoming quite common in criminal trials as a key factor is establishing guilt or innocence.
Biochemistry is a growing and complex field, with many challenges and the potential to contribute to our understanding, and the quality, of our lives.
