BIO 310 Lecture Notes - Lecture 8: Cell Cycle, Multicellular Organism, Homeostasis
Document Summary
Cancers are generally caused by dysregulation of the cell cycle. Some neurons are born and never divide again. Red blood cells are constantly turning over and dividing. Need a fine balance between cell proliferation, growth arrest, and cell death for embryonic development and adult tissue homeostasis. At first, they don"t divide that frequently. Then, there is a transit amplifying step = rapid cell cycles (common in stem cells) Afterwards, the cells terminally differentiate (stop cycling) Evolution of multicellularity and modulation of the cell cycle. At first, there were only unicellular organisms. The only thing preventing them from dividing was nutrient uptake and growth cells kept dividing as long as there was food. In cancer, cells essentially go back their unicellular state constantly dividing as long as there are nutrients. Cells eventually became colonial (they stick together) Cells had to figure out which ones divided and which ones didn"t. Cell cycle control was necessary in order to evolve to multicellularity.
