Synthetic Biology: How Scientists Are Learning to Write the Code of Life

For most of Earth's history, living things could only read the instructions written in their genes. Today, for the first time, humans are learning not just to read but to write new versions of these instructions. This emerging field is called synthetic biology, and it sits at the meeting point of biology, chemistry and computing.

At the centre of all life is a molecule called DNA, short for deoxyribonucleic acid. DNA is found inside cells and carries instructions in a simple four-letter alphabet, written as A, T, G and C. The complete set of DNA in an organism is called its genome. Genes within the genome carry the codes for proteins, which do most of the work in a cell. Interestingly, gene numbers do not match complexity. A common bacterium has about 4,300 genes, a fruit fly around 17,000, a mouse about 21,000 and a human roughly 22,000. What matters is not the number of genes but how, when and where they are switched on and off.

The cost of reading DNA has fallen sharply. Sequencing the first human genome took more than a decade, cost close to three billion dollars and involved thousands of scientists. The same task can now be done in hours for a few hundred dollars. With powerful computing and artificial intelligence, scientists can analyse genomes and even design new ones. A landmark moment came in 2010 when scientist J. Craig Venter and his team built a complete bacterial genome from chemicals and placed it into a cell, creating what was, in effect, a digitally designed life form. Another approach, led by researchers such as Jack Szostak, tries to build a simple cell from scratch to understand how life first began.

These advances bring both promise and danger, often described as the 'genie conundrum'. Engineered cells already make medicines, fuels, chemicals and materials, and their uses are expected to grow widely. But unlike a machine or a power plant, living things can copy themselves, which makes the technology harder to control. Experts stress the need for careful regulation so that the power of synthetic biology is used wisely and safely.

For exams, this topic links to Science and Technology in the General Studies syllabus. Aspirants should know the basics of DNA, genes, the genome and the Human Genome Project, along with applications of genetic engineering such as vaccines, gene therapy and bio-manufacturing. The ethical and biosafety concerns around editing and creating life are also important for essay and interview preparation.