> [!info]- Note Disclaimer > > > --- # Meiosis **Meiotic maturation** of an animal oocyte (egg cell) occurs when interceullar signals trigger the oocyte to exit from an arrested state at prophase of meiosis I and advance through mieosis in preparation for fertilization - [?] What does “preparation for fertilization” mean? Is it after the sperm and egg cell begin to combine? ## Meiosis I Meiosis II is more similar to Mitosis than Meiosis I is > [!abstract] Chromosome Movement > ![[Pasted image 20220830133954.png]] | Protein | Function | | ------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Cohesion** | Similar role from Mitosis.<br><br>Both mitotic and meiotic versions of cohesion exist so some can be selectively cleaved during Anaphase I, while others remain until Anaphase II. | | **Shugoshin** | Recruits a phosphatase to centromeres where it dephosphorylates Rec8 of cohesin. This makes the meiotic versions of cohesin resistant to separase. | | **Separase** | Similar function from Mitosis. | - In Meiosis I, the cause of the tension that holds the chromatids together is crossing over - There does need to be partial cohesion cleavage during Prophase I - In Meiosis II, the tension is caused by cohesin proteins The process of meiosis is often deemed a “fair” process in terms of random gene segregation. However, certain “selfish genes” have found ways to increase their transmission rates. ## Meiosis II ---