Before the genetic code was deciphered, the question of the origin of life has always fascinated scientists and physicists in particular.
Following the huge breakthrough in 1953 of scientists Francis Crick and James Watson, one big question remained unanswered:
How do you get from a strand of DNA to a protein?
Many scientists set to the challenge, but three in particular Marshall Nirenberg, Har Gobind Khorana and Robert Holley were the first to discover how the four bases of DNA could be translated into the 20 building blocks of proteins, also known as amino acids.
In 1968, they received the Nobel Prize for Physiology and Medicine for their interpretation of the genetic code and its function in protein synthesis. Nirenberg and Khorana unravelled the secrets of the genetic code; Holley sequenced and deduced the structure of the first RNA molecule.
DNA is made of chemical building blocks called nucleotides. These building blocks are made of a phosphate group, a sugar group and four types of nitrogen bases.
The four bases are divided in two groups: purines and pyrimidines. The purines are Adenine (A) and Guanine (G) and the pyrimidines are Cytosine (C) and Thymine (T).
In DNA, the two strands run in opposite directions and the bases pair up such that A always pairs with T and G pairs with C. In this way the information encoded in DNA is redundant, so one strand could be reconstructed from the other. This particular pairing scheme is known as the Watson-Crick pairing.
Furthermore, instructions in DNA are subdivided into subsets called genes. Each gene contains the information that is used to build a specific protein. A protein is an organic molecule that consists of amino acids joined by peptide bonds, and performs different functions in an organism. The process by which a gene is read and its corresponding protein is synthetized is called protein biosynthesis.
Throwback to 1961, Marshall Nirenberg, a young biochemist at the National Institute of Arthritic and Metabolic Diseases, found out how the genetic information hidden in the DNA strand could eventually be read out as a protein. He identified the first “triplet”, a sequence of three bases of DNA that codes for one of the 20 amino acids that serve as the building blocks of proteins.
His early interest in bird watching led him to the science of biology and he became very interested in the question of life and its essence. As a biochemist researcher in the Section of Metabolic Enzymes at the National Institutes of Health (NIH), he began working on how to decipher the RNA code.
In subsequent years, Nirenberg and his group resolved the entire genetic code by matching amino acids to synthetic triplet nucleotides.
His experiment demonstrated that messenger RNA transcribes genetic information from DNA, regulating the assembly of amino acids into complex proteins.
They also showed that with few exceptions, the genetic code is universal to all life on earth.
Finally, the language of DNA was understood.
The New York Times reported that Nirenberg’s research showed that biology has reached a new frontier and a journalist suggested that the biggest news story of the year was not Russian cosmonaut Yuri Gagarin orbiting the earth but the cracking of the genetic code!
This biological method of information storage is among the most important topics in modern biology: the genetic code is a set of instructions for transferring genetic data stored in the form of DNA or RNA into proteins. Proteins are integral to almost all of the biological processes that occur in living things. They are made up of amino acid sequences, and amino acids are produced based on the sequence of the genetic code.
The idea of cracking the human genetic code was to create a library of genes that could be used to answer questions such as what specific genes do and how they work.
If there are mutations or errors in the DNA, the message may be changed and can cause a cell to make (or not) proteins that affect how it grows and divides into new cells. Certain mutations can incite cells to grow out of control or not died as programmed which can lead to cancer.
For instance, when BRCA1 and BRCA2 genes suffer a mutation, DNA damage may not be repaired properly and cells are more likely to develop additional genetic alterations resulting in breast and/or ovarian cancer.
Early detection and precise identification of BRCA1 and BRCA2 variants makes the difference.