BIOL 152 Study Guide - Final Guide: Lysosome, Diploblasty, Cambrian Explosion
Document Summary
The cambrian explosion:542 mya: at the beginning of the paleozoic, most animal phyla and all major body plans appeared, during paleozoic, fishes dominate the marine environment. Insects and plants colonize land: amphibians then reptiles appear on land. Causes of cambrian explosion: new predator-prey relationships. Increase in atmospheric oxygen: hox (homeotic) gene complex arose, regulatory genes. Early developmental patterns: the zygote proceeds through several stages of mitotic divisions: cleavage, blastula, and gastrula. Animals are made of specialized cells: specialized cells are combined in tissues, connective, muscle, nervous, epithelial, tissues are combined into organs, organs work together in organ systems, only in bilaterians. Further classification of triploblasts: presence of a coelem, funtions, cushions, hydrostatic skeleton- where muscles are pushing on a water filled cavity to move the organism forward. Internal organs move and grow independently of the outer body: protostome or deuterostome, protostome- mouth develops from blastopore, deuterostomes- anus develops from blastopore.
