Eukaryotic Cells Lab Report

For eukaryotic cells, it has been believed that their is a succession of different CDK’s that are needed in different stages of the cell cycle. An example of this if in animal cells, there appears to be at least 3 CDK proteins and several different cyclins that operate just at G1, the first growth phase. The multiple CDKs and substrates are the driving factor behind cells going through the cell cycle and mitosis. Yeast are single-celled organisms that are eukaryotes since they have a nucleus where their genetic material is stored. Fission yeast have challenged this model since four CDK-cyclin complexes were replaced by one CDk-cyclin complex, which was composed of Cdc13 cyclin and Cdc2. The outcome of this experiment resulted in a single CDK complex, with the absence of multiple CDK complexes, can progress through the mitotic and meiotic cell cycle.

The outcome of decreased Cdc13 levels didn't change premeiotic S-phase but inhibited the meiotic nuclear divisions. Next, they looked ati the roles of the G1/S mitotic cyclins cig1, cig2 and puc1 in the meiotic cell cycle. Cig2 was important one, since the absence cig2 delays progression into premeiotic S-phase and meiotic nuclear divisions and caused defects in the zygotes of meiosis II. They then looked at meiotic cyclins and discovered that Rem1 and Crs1 cyclins have no essential roles in meiotic cell cycle when the mitotic cyclins are present. After they look at mitotic cyclins during meiosis and the results showed mitotic and meiotic cyclins are required for meiotic cell cycle progression. From the information gather, they attempted to engineers a single CDK-cyclin complex that could drive meiotic cell cycle and they started with a fusion protein between Cdc13 and Cdc2. The CDK activity could drive premeiotic S-phase but not meiotic nuclear