DNA: Decoding the Language of Life

In 1865, Gregor Mendel discovered the laws of heredity through pea plant experiments, but the world didn't notice his discovery until after his death. 35 years later in 1900, three scientists independently rediscovered Mendel's paper. However, what the genetic material actually was remained a mystery. In 1944, Oswald Avery proved through pneumococcal experiments that DNA, not protein, carries genetic information. But the scientific community was skeptical at the time. The decisive turning point was the 1952 Hershey-Chase experiment. By proving that only the DNA of bacteriophages (bacterial viruses) is injected into bacteria, it became certain that DNA is the genetic material. The remaining task was to determine its structure.

In 1953, Watson and Crick of Cambridge University announced the double helix structure of DNA. But this discovery has a complex history. Rosalind Franklin at King's College was researching DNA structure using X-ray crystallography. 'Photo 51' she took in May 1952 was the decisive image clearly showing DNA's helical structure. However, Watson secretly obtained and viewed this photo from Franklin's colleague Maurice Wilkins, and this became the key to building the double helix model. Franklin did not know this. In 1962, Watson, Crick, and Wilkins received the Nobel Prize in Physiology or Medicine. Franklin had died of cancer in 1958 at age 37, and the Nobel Prize is not awarded posthumously. Today, many scientists evaluate that Franklin's failure to receive recognition for her contribution of 'Photo 51' was due to the sexist culture of science at the time.

In 2012, Jennifer Doudna and Emmanuelle Charpentier proved that the CRISPR-Cas9 system could be used as a gene editing tool. CRISPR was discovered in bacteria's immune system. Bacteria remember the DNA sequences of viruses that attacked them in the past, and when the same virus comes again, they cut and destroy that DNA with the Cas9 protein. Scientists have reprogrammed this system to precisely cut and replace any desired gene. Currently, CRISPR is being clinically applied to cure sickle cell anemia, eliminate HIV, and restore vision through gene therapy. In 2023, a sickle cell anemia treatment received FDA approval. However, ethical issues are also being raised regarding gene editing of human embryos, indiscriminate modification of crops, and the possibility of biological weapon development.