Sperm and egg morphology and cell cycle during oogenesis Flashcards
What are the main features of sperm?
The cytoplasm is greatly reduced, leaving just a lot of mitochondria, a haploid nucleus, and an acrosome. Move with a flagella
What are the main features of an egg?
Large, accumulates proteins and mRNA in the cytoplasm along with other proteins and lipids for nutrition, will have organelles
What is seen for external protection for eggs?
Jelly coat in some species. Mammals have the corona radiata and zona pellucida
How do sperm undergoing spermiogenesis reduce their cytoplasm?
They lose a lot of the water and contract
What are the two blocks to meiosis in amphibians?
Diplotene and metaphase blocks
What releases the egg from the diplotene block?
Mitosis promoting factor that is phosphorylated
What is the signal that causes the egg to be released from the diplotene block?
Progesterone
What causes progesterone to be produced in a female frog?
Seasonal changes to light and temperature
What happens in the egg after the diplotene block is released?
The egg finishes meiosis 1 to produce an oocyte and a polar body, and it starts meiosis 2 until it hits the metaphase block
What releases the egg from the metaphase block?
Degradation of cytostatic factor caused by fertilization
Why does fertilization result in the egg being released from the metaphase block?
The wave of released calcium causes CSF to be degraded
What happens to the egg once released from the metaphase block?
Finishes meiosis 2 and ends up with 3 polar bodies outside
