cell cycle nobel lecture paragraph - discovery of CDK

Hartwell’s main discovery was that of CDC genes and the role they play in such cell cycle events in yeast as budding, DNA synthesis, nuclear division cytokinesis and cell division. Hartwell conducted various experiments arresting yeast cells at different points in the cell cycle, as well as comparing the phenotypic defects of cells mutant for the CDC28 gene and others with wild-type yeast cells. He found that the CDC28 gene was required for the commencement of two pathways. The first involved in budding, nuclear migration, cytokinesis and cell division and the other involving DNA replication, nuclear division and joined the first pathway prior to cytokinesis and cell division. Although not referred to in the paper, I interpreted this as concluding evidence of the CDC28 gene being involved in both asexual and sexual reproduction pathways of yeast. Hartwell did however talk about research done by Duntze and Maney regarding the connection between the secretion of pheromones by M ata cells and control of the cell cycle and specifically inhibition of DNA synthesis. Hartwell states that following his discovery of the CDC28 gene, the work Paul Nurse did regarding cyclin dependent kinases unified the cell cycle field. Nurse worked on the CDC2 gene, which he determined its expression to be the rate-limited step of mitosis in S. pombe.