The Nobel Prize in Physiology or Medicine 2001 ... - Ijsidonline.info

ISSN:2249-5347IJSIDInternational Journal of Science Innovations and DiscoveriesAn International peerReview Journal for Sciencewere altered (mutated). By this approach he succeeded to identify more than one hundredgenes specifically involved in cell cycle control, so called CDC-genes (cell division cyclegenes). One of these genes, designated CDC28 by Hartwell, controls the first step in theprogression through the G1-phase of the cell cycle, and was therefore also called "start".In addition, Hartwell studied the sensitivity of yeast cells to irradiation. On the basisof his findings he introduced the concept checkpoint, which means that the cell cycle isarrested when DNA is damaged. The purpose of this is to allow time for DNA repair beforethe cell continues to the next phase of the cycle. Later Hartwell extended the checkpointconcept to include also controls ensuring a correct order between the cell cycle phases.A general principlePaul Nurse followed Hartwell's approach in using genetic methods for cell cyclestudies. He used a different type of yeast, Schizosaccharomyces pombe, as a modelorganism. This yeast is only distantly related to baker's yeast, since they separated fromeach other during evolution more than one billion years ago.In the middle of the 1970s, Paul Nurse discovered the gene cdc2 in S. pombe. Heshowed that this gene had a key function in the control of cell division (transition from G2to mitosis, M). Later he found that cdc2 had a more general function. It was identical to thegene ("start") that Hartwell earlier had identified in baker's yeast, controlling the transitionfrom G1 to S.This gene (cdc2) was thus found to regulate different phases of the cell cycle. In1987 Paul Nurse isolated the corresponding gene in humans, and it was later given thename CDK1 (cyclin dependent kinase 1). The gene encodes a protein that is a member of afamily called cyclin dependent kinases, CDK. Nurse showed that activation of CDK isdependent on reversible phosphorylation, i.e. that phosphate groups are linked to orremoved from proteins. On the basis of these findings, half a dozen different CDK moleculeshave been found in humans.Call for research and Review articles publication: ijsidonlineinfo@gmail.com

ISSN:2249-5347IJSIDInternational Journal of Science Innovations and DiscoveriesAn International peerReview Journal for Sciencemechanisms controlling the cell cycle. CDK-molecules and cyclins drive the cell from onephase to the next. The CDK-molecules can be compared with an engine and the cyclins witha gear box controlling whether the engine will run in the idling state or drive the cellforward in the cell cycle.For more details please visit:http://www.nobelprize.org/nobel_prizes/medicine/laureates/2001/press.htmlCall for research and Review articles publication: ijsidonlineinfo@gmail.com