Week 9: The Cell Cycle. Part 3 | The Pennsylvania State University

University:
The Pennsylvania State University
Course:
BIOL 230W | Cellular Biology
Academic year:

2023
Views:

347

Pages:

1
Author:

Sarah Landeck

BIOL 230W - Week 9 The Cell Cycle pt 3 — Progression through cell cycle is regulated by CDK/cyclin interactions —> CDK levels are constant but cyclin levels fluctuate (highest at M phase) —> active CDK phosphorylates target protein to change conformation — There are 3 checkpoints *copy info from packet — Mitogen: a substance that stimulates cell division or mitosis —> G0 cells are not dividing (quiescence) - stim by mitogens to start dividing — Myc is a mitogen because it upregulates cyclins (proto-oncogene) —> Proto-oncogenes support normal cell division – oncogene is a mutated version that does not correctly regulate cell division. The Cell Cycle pt 4 — p53 protein acts as a tumor suppressor, released in response to cell stress The Cell Cycle pt 5 — Cohesin holds sister chromatids together at the kinetochore —> cohesin is degraded by the enzyme separase during metaphase — The final checkpoint during the cycle is called the metaphase checkpoint, metaphase checkpoint signal inhibits CDC20 protein that activates separase —> signal is turned on when there are kinetochores unbound to microtubules — Chromosomal instability is a common cause of tumor development