Animal Diversity and Development Flashcards
how many animal species have been identified?
1.3 million living species
what defines aniaml?
being efficient consumers of other organisms
what do animal tissues develop from and what are cells supported by?
tissues develop from embryonic layers and cells are supported by collagen (proteins)
what do animals do with nerve impulses?
move and conduct them
what are two asexual modes of reproduction in animals?
budding and parthenogenesis
list the levels of organization in order
cells -> tissues -> organs -> organ systems -> organism
how does the zygote develop into the blastula?
zygote undergoes mitotic divisions of cell cleavage 3 times to result in an 8 cell embryo
what happens to the 8 cell embryo after it is formed?
it cleaves again to produce blastula
what is a blastula?
hollow ball of cells containing the bastocoel
what happen after the blastula is formed?
it undergoes gastrulation where the embryo folds inward to produce 3 layers of cells
what are the 3 layers formed from gastrulation?
ectoderm, mesoderm, and endoderm
what does the endoderm give rise to?
tissue lining in digestive tract
what is metamorphosis?
process that turns animals into a juvenile that resembles an adult but is not yet sexually mature
what are home box genes?
highly conserved genes (have remained untamed) that regulate expressions of other genes
what are hox genes?
control of expression of many genes that influence morphology during embryonic development
what is the colonial hypothesis?
states that single cell protists that were ancestral to animals stuck together, took on specialized functions, folded in, and gave rise to radially symmetrical animals
what is the syncytial hypothesis?
large protists with multiple nuclei in one cell membrane formed boundaries b/w nuclei to give rise to a mass of cells leading to bilateral animals
what are required for the origin of multicellularity and what do they form?
cells adhere to and signal each other, protists form colonies that resemble collar cells in sponges
what molecular evidence supports the origin of multicellularity?
1) 78 protein domains in choanoflagellates are known to other animals
2) CCD domain only found in animals but was found in coanoflagelados
what are cadherines?
genes that encode proteins that play key roles in how animals attach to one another and cell signaling pathways
