BIOL 1412 Chapter Notes - Chapter 44: Spindle Apparatus, Gsk-3, Blastomere
4 Apr 2016
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Fusion of sperm and egg (fertilization) accomplishes several things: Ion fluxes across the membrane, sets up blocks to stop more sperm from entering, changes ph of cytoplasm, increases egg metabolism and stimulates protein synthesis, and initiates rapid cell division. The sperm and the egg make different contributions to the zygote: everything the zygote needs in early stage comes from mother"s egg cell, sperm contributes its haploid nucleus, and the centriole. Centriole contributes centrosome (which organizes the mitotic spindle for cell division) and creates microtubules (used for cilia and cell signaling) Cortical cytoplasm rotates toward site of sperm entry, which touches animal and vegetal poles, which produces a band of pigmented cytoplasm on opposite side of sperm entry. When this gray crescent forms, the centriole initiates cytoplasmic regorgnaization. The movement of cytoplasm, proteins, and organelles changes distribution of signals. Changes around distribution of b-catenin and a protein kinase called gsk-3 (the gsk-3 phosphorylates b- catenin, degrading it), and a gsk-3 inhibitor.
