The first stamp shows the discovery of the role of chromosomes in heredity. Thomas Hunt Morgan used the fruit fly (Drosophila melanogaster) to demonstrate how the chromosome crossing over gives raise to the ratios 3:1 and 9:3:3:1 in phenotypes. He received Nobel Prize in 1933.
The second stamp depict the discovery of DNA structure - the double helix - by James Dewey Watson, Francis Crick and Maurice Wilkins in 1953. The breakthrough was actually based on the X-ray image of the nucleic acids and chemical composition of the four bases in a nucleic acid solution. The discovery of the double helix had indeed shocked the world in 1950s. Three of them received Nobel Prize in 1962.
The third stamp on the discovery of restriction enzymes by three microbiologists namely Werner Arber, Daniel Nathans and Hamilton Othanel Smith. Restriction enzymes are only found in bacteria. The bacteria use restriction enzymes for self defense from invasion of viruses by cutting the DNA of viruses into pieces. The restriction enzymes are then used by molecular biologists to cut (as a pair biological scissor) DNA into desired fragments for DNA manipulation (biotechnology). Three of them received Nobel Prize in 1978.
Finally, the forth stamp is on the discovery of jumping gene by a cytogeneticist Barbara McClintock. Barbara McClintock studied maize/corn, and she discovery certain genes could be moved around the genome of maize/corn. These movable element is called as transposable element or jumping gene. She received Nobel Prize in 1983.
These stamps are beautifully printed by recess printing. I just love them.
