Study Guide for Chapter 31

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Department
Biological Sciences
Course
BIOA02H3
Professor
Mary Olaveson
Semester
Winter

Description
Biology Chapter 31 Animals Origins and the Evolution of Body Plans Convincing evidence that all organisms considered to be animals share a common ancestor comes form there many shared derived molecular and morphological traits, much of which we have described in earlier chapters: -Many gene sequences such as the ribosomal RNA genes support the monophyly of animals. -Animals display similarities in the organization and function of their Hox genes -Animals have unique types of junctions between their cells (tight junctions, desmosomes, and gap junctions) -Animals have common extracellular matrix molecules, including collagen and proteoglycans -Clues to the evolutionary relationships among animal groups thus must be sought in derives traits that are found in some groups such as -Characteristics in fossils -Patterns in embryonic development -Morphology -Physiology of living animals, - The structure of animal molecules and in the genomes of animals (mitochondrial and RNA genes) Cleavage- the first few cell divisions of a zygote Cleavage patterns- different ways of cell division among different animals? -patterns are influenced by the configuration of the yolk the nutritive material that nourishes the growing embryo. Diploblastic animals- have only two of these cell layers: ectoderm- outer layer endoderm- inner layer Triploblastic animals- have three cell layers ectoderm endoderm mesoderm-lies between the ectoderm and endoderm Gastulation- a process where a hollow ball one cell thick indents to form a cup shaped Structure Blastopore- the opening of the cavity formed by this indentation -The pattern of development after formation of the blastopore has been used to provide the triploblastic animals into two major groups: 1) Protostomes- mouth first, the mouth arises from the blastopore; the anus forms later - Appears to be the derived condition 2) Deuterstomes-mouth second, the blastopore becomes the anus; the mouth forms later. - Appears to be the ancestral condition Body plan - the general structure of an animal, the arrangement of its organ systems, and the integrated functioning of its parts www.notesolution.com
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