Molecular biology is the scientific study of the molecular basis of life processes, including cellular respiration, excretion, and reproduction. This branch of biology deals with the nature of biological phenomena at the molecular level through the study of DNA and RNA, proteins, and other macromolecules involved in genetic information and cell function, characteristically making use of advanced tools and techniques of separation, manipulation, imaging, and analysis.
The term molecular biology was coined in 1938 by Warren Weaver, then director of the natural sciences program at the Rockefeller Foundation. In 1950 W. T. Astbury of the University of Leeds used the term in its now accepted sense, to describe the area of research, closely related to and often overlapping biochemistry, conducted by biologists whose approach to and interest in biology are principally at the molecular level of organization. The field of molecular biology has grown with the increasing sophistication of available techniques and has quickly built upon its own increases in the understanding of biological processes. In the 1930s, with the help of the technique of ultracentrifugation, macromolecules were first studied in detail. Later, with the use of X-ray crystallography their three-dimensional structures were described. In the 1940s the process by which individual genes produce their unique products began to be understood as resulting from the different sequences of the base pairs that make up the genes.
In the 1950s Linus Pauling described the three-dimensional structure of proteins, and James Watson and Francis Crick described the double helix of the DNA molecule. Further advances were made in understanding DNA, protein, and virus synthesis and the regulation of genes, and by the 1970s, the techniques of genetic engineering were enabling molecular biologists to study higher plants and animals, opening up the possibility of manipulating plant and animal genes to achieve greater agricultural productivity. Such techniques also opened the way for the development of gene therapy.
Timeline of Molecular Biology Discoveries
The chief discoveries of molecular biology took place in a period of only about twenty-five years.
|1940||George Beadle and Edward Tatum demonstrated the existence of a precise relationship between genes and proteins. In the course of their experiments connecting genetics with biochemistry, they switched from the genetics mainstay Drosophila to a more appropriate model organism, the fungus Neurospora; the construction and exploitation of new model organisms would become a recurring theme in the development of molecular biology.|
|1944||Oswald Avery, working at the Rockefeller Institute of New York, demonstrated that genes are made up of DNA.|
|1952||Alfred Hershey and Martha Chase confirmed that the genetic material of the bacteriophage, the virus which infects bacteria, is made up of DNA.|
|1953||James Watson and Francis Crick discovered the double helical structure of the DNA molecule.|
|1960||Rene Dubos works on antimicrobial agents and environmental protection F. M. Burnet and Peter B. Medawar receive Nobel Prize for the discovery of acquired immunological tolerance.|
|1960||"Ames Test" to screen for mutagens developed by Bruce Ames.|
|1961||Francois Jacob and Jacques Monod hypothesized the existence of an intermediary between DNA and its protein products, which they called messenger RNA.|
|1961-1965||The relationship between the information contained in DNA and the structure of proteins was determined: there is a genetic code, which creates a correspondence between the succession of nucleotides in the DNA sequence and a series of amino acids in proteins. Monod and Jacob also demonstrated how certain specific proteins, called regulative proteins, latch onto DNA at the edges of the genes and control the transcription of these genes into messenger RNA; they direct the "expression" of the genes.|
|1973||Herbert Boyer and Stanley Cohen, using plasmids, are the first to clone DNA.|
|1976||Michael Bishop and Harold Varmus discover the cancer-causing genes, called oncogenes, and find that such genes are in normal tissues.|
|1978||Daniel Nathans, H.O. Smith and Werner Arber receive Nobel Prize for using restriction enzymes to map viral genomes.|
|1982||Stanley Prusiner isolates a protein from a slow disease infection and suggests that it might direct its own replication. He suggests the agent be termed a prion.|
|1983||Luc Montagnier of France and Robert Gallo of the United States independently isolate and characterize the human immunodeficiency virus (HIV) the cause of AIDS.|
|1983||Kary Mullis invents the polymerase chain reaction.|
|1983||Barbara McClintock receives the Nobel Prize for discovery of mobile genetic elements.|
|1994||The Food and Drug Administration approves the first genetically engineered food for human consumption, a slower ripening tomato.|
|1995||The Food and Drug Administration approves the first protease inhibitor, a major weapon against the progression of AIDS.|
|1996||Peter C. Doherty and Rolf M. Zindernagel receives Nobel Prize for the discovery of how the immune system recognizes virus-infected cells.|
|1997||The first complete nucleotide sequence of all of the chromosomes of eukaryote is reported (yeast).|
- A. Darbre, Introduction to Practical Molecular Biology (1988).