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Bioscience Topics

Molecular Biology

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Molecular biology is the study of the structure function, and makeup of the molecular building blocks of life. It focuses on the interactions between the various systems of a cell, including the interrelationship of DNA, RNA and protein synthesis and how these interactions are regulated. The youngest of the biosciences, molecular biology is closely interrelated with the fields of biochemistry, genetics and cell biology.

Molecular biology traces its origins to the 1930s, when scientists focused on explaining the phenomena of life by studying the macromolecules that generate life. The chief discoveries of molecular biology took place in a period of only about 25 years, starting in 1940, when George Beadle and Edward Tatum established the existence of a precise relationship between genes and proteins (they shared the 1958 Nobel Prize in Medicine). Another 15 years were required before new and more sophisticated technologies, united today under the name genetic engineering, would permit the isolation and characterization of genes.

The truly fundamental discovery during the first 25 years of molecular biology took place in 1953, when James Watson and Francis Crick discovered the double helical structure of the DNA molecule (for which they shared the Nobel Prize in Medicine in 1962). And 30 years later, Kary Mullis jump-started the field of genetic engineering when he invented the polymerase chain reaction, an elegantly simple “biological copy machine” that rapidly can produce many copies of a specific piece of DNA in the lab. Mullis and Michael Smith shared the 1993 Nobel Prize in Chemistry for devising this technological milestone in molecular biology.

The discovery of the mechanism of heredity has proven to be a major breakthrough in modern science. Another important advance came in understanding how molecules conduct metabolism, or how they process the energy needed to sustain life. The techniques of genetic engineering enable 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.

An ambitious international effort in molecular biology began in 1990 with the initiation of the now-completed Human Genome Project (HGP). Its goal was to discover all the estimated 20,000 to 25,000 human genes and make them accessible for further biological study. Another project goal was to determine the complete sequence of the three billion DNA subunits (bases in the human genome). As part of the HGP, parallel studies were carried out on selected model organisms such as the bacterium E. coli and the mouse to help develop the technology and interpret human gene function. The Department of Energy Human Genome Program and the National Institutes of Health’s National Human Genome Research Institute together sponsored the HGP.

Subdisciplines of Molecular Biology

Comparative Genomics

This is the study of human genetics by comparisons with model organisms such as mice, the fruit fly and the bacterium E. coli.

DNA Forensics

This is the use of DNA for identification. Some examples of DNA use are to establish paternity in child support cases, to establish the presence of a suspect at a crime scene and to identify accident victims.

Functional Genomics

This is the study of genes, their resulting proteins and the role played by the proteins in the body’s biochemical processes.

Gene Therapy

This is an experimental procedure aimed at replacing, manipulating or supplementing nonfunctioning or misfunctioning genes with healthy genes.


This is the study of genes and their functions.

Molecular Genetics

This is the study of macromolecules important in biological inheritance.


This is the study of the interaction of an individual’s genetic makeup and response to a drug.


This is the study of the full set of proteins encoded by a genome.

Structural Genomics

This is the effort to determine the three-dimensional structures of large numbers of proteins using both experimental techniques and computer simulation.


This is the study of how genomes respond to environmental stressors or toxicants.