Biotechnology has been used in a rudimentary form since ancient brewers began using yeast cultures to make beer. The breakthrough that laid the groundwork for modern biotechnology came when the structure of DNA was discovered in the early 1950s. To understand how this insight eventually led to biotech therapies, it’s helpful to have a basic understanding of DNA’s central role in health and disease.
What does DNA do?
DNA is a very long and coiled molecule found in the nucleus, or command center, of a cell. It provides the full blueprint for the construction and operation of a life-form, be it a microbe, a bird, or a human. The information in DNA is stored as a code made up of four basic building blocks, called nucleotides. The order in which the nucleotides appear is akin to the order of the letters that spell words and form sentences and stories. In the case of DNA, the order of nucleotides forms different genes. Each gene contains the instructions for a specific protein.
With a few exceptions, every cell in an organism holds a complete copy of that organism’s DNA. The genes in the DNA of a particular cell can be either active (turned on) or inactive (turned off) depending on the cell’s function and needs. Once a gene is activated, the information it holds is used for making, or “expressing,” the protein for which it codes. Many diseases result from genes that are improperly turned on or off.
Protein production is a multistep process that includes transcription and translation. During transcription, the original DNA code for a specific protein is rewritten onto a molecule called messenger RNA (mRNA); mRNA has nucleotides similar to those of DNA. Each successive grouping of three nucleotides forms a codon, or code, for one of 20 different amino acids, which are the building blocks of proteins.
During translation, a cell structure called a ribosome binds to a ribbon of mRNA. Other molecules, called transfer RNAs, assemble a chain of amino acids that matches the sequence of codons in the mRNA. Short chains of amino acids are called peptides. Long chains, called polypeptides, form proteins.
What functions do proteins control?
The amino acids that form a protein interact with each other, and those complex interactions give each protein its own specific, three-dimensional structure. That structure in turn determines how a protein functions and what other molecules it impacts. Common types of proteins are:
Given the tremendous variety of functions that proteins perform, they are sometimes referred to as the workhorse molecules of life. However, when key proteins are malfunctioning or missing, the result is often disease of one type or another.
When segments of DNA are cut and pasted together to form new sequences, the result is known as recombinant DNA. When recombinant DNA is inserted into cells, the cells use this modified blueprint and their own cellular machinery to make the protein encoded by the recombinant DNA. Cells that have recombinant DNA are known as genetically modified or transgenic cells.
These new modes of treatment give drug developers more options in determining the best way to counteract a disease. But biotechnology research and development (R&D), like pharmaceutical R&D, is a long and demanding process with many hurdles that must be cleared to achieve success.