DNA: History and discovery

Friedrich Miescher Discovers Nuclein

1869

In 1869, Swiss biochemist Friedrich Miescher discovered a substance in the nuclei of cells that he called "nuclein." He found that this substance contained both nitrogen and phosphorus, and he speculated that it might play a role in heredity. Although Miescher did not fully understand the significance of his discovery at the time, his work laid the foundation for future research on the structure and function of DNA

Frederick Griffith's Experiments with Pneumococcus Bacteria

1928

In 1928, British bacteriologist Frederick Griffith conducted a series of experiments with pneumococcus bacteria that led to the discovery of "transformation." Griffith found that when he injected mice with a mixture of live non-virulent bacteria and heat-killed virulent bacteria, the mice became infected with the virulent strain. This suggested that something in the dead bacteria was able to transform the non-virulent strain into a virulent one.

Avery, MacLeod, and McCarty Confirm DNA as the Genetic Material

1944

In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty published a landmark paper in which they confirmed that DNA was the transforming substance identified by Griffith. They demonstrated that when they destroyed the DNA in heat-killed virulent bacteria, the transforming activity was lost. This provided strong evidence that DNA was the genetic material, and paved the way for further research on its structure and function.

Hershey and Chase's Experiments with Bacteriophages

1952

In 1952, scientists Alfred Hershey and Martha Chase conducted a series of experiments with bacteriophages, viruses that infect bacteria. They used radioactive labeling to track the movement of the virus's genetic material, and found that only the DNA entered the bacterial cells and directed the production of new viruses. This provided further evidence that DNA, not proteins, was the carrier of genetic information.

Watson and Crick Discover the Double Helix

1953

In 1953, James Watson and Francis Crick published a paper in the journal Nature describing the structure of DNA. Using X-ray crystallography data from Rosalind Franklin and Maurice Wilkins, they proposed that DNA was made up of two complementary strands that twisted together to form a double helix. This discovery revolutionized the field of genetics and led to a greater understanding of how DNA carries and transmits genetic information.

Marshall Nirenberg and Heinrich Matthaei Crack the Genetic Code

1961

In 1961, Marshall Nirenberg and Heinrich Matthaei performed a series of experiments in which they added synthetic RNA sequences to a cell-free system and observed the production of specific amino acids. This led them to crack the genetic code, determining the correspondence between the sequence of nucleotides in RNA and the sequence of amino acids in proteins.

Thomas Cech Discovers Ribozymes

1968

In 1968, Thomas Cech discovered that some RNA molecules were capable of catalyzing chemical reactions, challenging the prevailing belief that only proteins could serve as enzymes. He called these RNA molecules "ribozymes," and his discovery opened up a new area of research into the role of RNA in cellular processes.

Paul Berg Creates the First Recombinant DNA Molecule

1972

In 1972, Paul Berg created the first recombinant DNA molecule by combining DNA from different sources. This breakthrough led to the development of new genetic engineering techniques, which have revolutionized fields such as medicine and agriculture.

Frederick Sanger Sequences the First Genome

1977

In 1977, Frederick Sanger became the first person to sequence an entire genome, that of the bacteriophage ΦX174. This paved the way for the development of new sequencing technologies and the study of more complex organisms.

Kary Mullis Invents Polymerase Chain Reaction (PCR)

1983

In 1983, Kary Mullis invented the polymerase chain reaction (PCR), a technique that allows for the amplification of DNA sequences. This breakthrough has revolutionized genetics research by making it possible to study small amounts of DNA and to create copies of specific genes for further study.

The Human Genome Project is Launched

1990

In 1990, the Human Genome Project was launched with the goal of mapping the entire human genome. This massive international effort took more than a decade and involved the sequencing of over three billion base pairs of DNA.

First Bacterial Genome is Sequenced

1995

In 1995, the first complete bacterial genome, that of Haemophilus influenzae, was sequenced. This marked a major milestone in genomics research and provided insights into the genetic basis of bacterial diseases.

The Human Genome is Sequenced

2001

In 2001, the Human Genome Project announced that it had completed the sequencing of the entire human genome. This achievement opened up new avenues for research into the genetic basis of human disease and the development of personalized medicine.

CRISPR-Cas9 is Discovered

2012

In 2012, Jennifer Doudna and Emmanuelle Charpentier discovered the CRISPR-Cas9 system, a powerful gene-editing tool that allows for precise and targeted changes to DNA. This breakthrough has revolutionized genetics research and opened up new possibilities for gene therapy and disease treatment.