ZOO 3050 Lecture Notes - Lecture 2: Cleavage Furrow, Spindle Apparatus, Polarity In Embryogenesis
2 Mar 2016
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Document Summary
Cleavage: create building blocks that will make up the individual. Yolk is what is used to fuel all processes during development. Birds and amphibians must be completely supported by the yolk. Compounds that drive cleavage such as mrna and proteins are put into the egg by the mother. As the cell divides during cleavage, the messenger signals are separated creating different species/individuals from identical mother cells. Three different tissue layers in this phase, ectoderm, mesoderm, and endoderm. Becomes a fetus at this point in humans (direct life cycle) Larval development: intermediate life stage that looks nothing like the adult form. Form and shape is optimized for gathering mass amounts of food, and move around the ocean. Metamorphosis: transform from larva into the adult form, becomes a reproductive adult. Fusion of two haploid gametes: sperm and egg. Once the diploid nucleus is formed, dna and protein synthesis is triggered, metabolic rate is increased to quickly drive cleavage.
