BIOL 119 Chapter Notes - Chapter 33: Programmed Cell Death, Cambrian Explosion, Comparative Anatomy
Document Summary
Eukaryotes: multicellular, with extracellular matrix, heterotrophs, move under their own power at some point in life cycle, all animals except sponges have. Only multicellular heterotrophs on the tree of life that usually ingest food before digest it. Animals are largest predators, herbivores, and deritivores on earth. Three types of data: fossils, comparative morphology, and comparative genomics. Multicellularity origin: animals are monophyletic, multicellularity appears to have originated in a sponge-like animal. Molecular evidence: specialization of cell types, regulation of cell cycling and growth, adhesion among cells and between cells and extracellular matrix, recognition of self and nonself, innate immunity, developmental signaling and gene regulation, programmed cell death. Series of important genetic innovations appear to have occurred at the very root of the animal tree along with multicellularity: subsequent duplication and diversification of these genes contributed to the diversification of animal lineages.
