Joseph Grafton Gall researched and taught cell biology for over seventy years in the late twentieth and early twenty-first centuries in the United States. Much of his early work revolved around the structure and function of chromosomes, which are structures made of DNA and protein found in cells. As a professor at Yale University in New Haven, Connecticut, Gall and his graduate student Mary-Lou Pardue developed in situ hybridization, a technique that uses probes to identify the location of specific DNA sequences along a chromosome. With another graduate student, Elizabeth Blackburn, he also performed research on the structure of telomeres, which are the ends of chromosomes. Gall was an early advocate for women in STEM and trained many female scientists, many of whom became successful in their fields. Gall studied the structure and function of different forms of genetic information, namely DNA and RNA, helping to expand the understanding of how those molecules replicate within cells.

As a researcher in biochemistry, Frederick Sanger studied the structure of proteins, RNA, and DNA during the mid-twentieth century in Cambridge, England. He was the first person to determine the amino acid sequence of a protein, the hormone insulin, which regulates blood sugar levels. Later, he developed an efficient method for sequencing the nucleotide bases in DNA, an organism’s hereditary material. Named Sanger sequencing in his honor, the method was a staple of molecular biology techniques for over forty years. It formed the backbone of methods used for the Human Genome Project, the international effort to sequence the DNA in a human genome, and foreshadowed the development of more modern DNA sequencing techniques. Sanger is one of only a handful of individuals to receive two Nobel Prizes. Through his work elucidating the structure of biological molecules and devising methods to sequence them, Sanger fundamentally shaped the course of biology in the twentieth century.