1953
1955
JAMES WATSON & FRANCIS CRICK
The pivotal X-ray crystallography work by Franklin and Wilkins , combined with Chargaff ' s base-pairing discovery , contributed to Watson and Crick ' s 1953 ground-breaking derivation of the threedimensional , double-helical model for the structure of DNA .
In 1962 , they , along with Maurice Wilkins , were awarded the Nobel Prize for Physiology & Medicine . Despite the fact that her photographs had been integral to the seminal discovery , Rosalind Franklin was not recognized - the excuse being that only three scientists could share the prize .
JOE HIN TJIO
Modern cytogenetics , the branch of genetics defined as the study of inheritance in relation to the structure and function of chromosomes , began in 1956 when Joe Hin Tijo made the first correct count of chromosomes in human cells : 46 chromosomes , arranged in 23 pairs . Previously , in 1923 , Theophilus Painter had reported a chromosome number of 48 .
Cytogenetics ’ first major impact on disease diagnosis occurred in 1959 when an additional copy of chromosome 21 was linked to Down ' s syndrome .