LIFE 121 Lecture Notes - Lecture 1: Human Embryogenesis, Triploblasty, Gastrulation
Document Summary
07/14/2015: what is an animal, multicellular, eukaryotic, heterotrophic, develop from embryonic layers, diploid stage generally dominates sexual life cycle, life cycles many animals also include at least 1 larval stage. Larva: sexually immature form of an animal that looks different from adult, usually eats different food and may even have different habitat than adult e. g. tadpole (larva) of frog. Animal larvae undergo metamorphosis = changes in tissues adult: genes controlling for animal development have been relatively conserved over evolutionary time. Many regulatory genes contain common modules of dna sequences; suggesting this gene family (hox genes) evolved in eukaryotic lineage that gave rise to animals. Animal body plans: symmetry, asymmetry = most sponges, radial symmetry= part of an animal radiate out from center. Any imaginary slice through central axis divides animal into mirror images: animals have a top (oral or mouth), side, and bottom (aboral); no head, read end, Or left or right: bilateral: animal has left and right side.
