BI236 Lecture Notes - Lecture 20: Mitosis, Cycl, Apoptosis
Document Summary
Lecture 20 the cell cycle (6:1) part 3 of 3 march 3rd 2017. Existence of a control molecule that triggers the onset of mitosis. As oocytes develop, they replicate their dna and become arrested in g2 as they grow in size. When stimulated by a male, an adult females ovarian cells secrete hormone progesterone, which induces the g2 arrested oocytes to enter meiosis i. Then oocytes continue through meiosis i, the succeeding interphase, and then arrest during the second meiotic metaphase. At this stage the cells are called eggs. When fertilized by sperm, the egg nucleus is released from its metaphase arrest and completes meiosis. The resulting haploid egg nucleus then fuses with the haploid sperm nucleus, producing a diploid zygote. Maturation promoting factor (mpf) induces oocyte (cid:862)maturation(cid:863) (i. e. meiotic division) Fluctuating levels of mitotic cyclin and mpf activity during cell cycle. Mitotic cdk is found consistently throughout the cell cycle.
