Biology Notes 3-10-08

Biology Notes 3-10-08 - -Functional specialization of cells...

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Biology Notes March 10, 2008 Animals have to eat: Eyes Mouth Digestive Organs Traits that distinguish animals: -All are multicellular – have development from a single cell through a blastula stage. -Sexual reproduction – usually only gametes are haploid. -All are heterotrophs. Animals are monophyletic, share derived traits: Evidence: a) Cells have unique junctions; tight junctions, desmosomes & gap junctions. b) Animals have a common set of extra cellular matrix molecules, c) Gene sequences such as those for rRNA support monopoly. d) Hox Genes : -The ancestor of the animal clade was probably a colonial flagellated protist.
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Unformatted text preview: -Functional specialization of cells in the colony arose; & cells continued to differentiate. Usually head and tail.-Coordination among cells may have been improved by regulatory molecules; eventually leading to larger, more complex animals.-Differences in derived traits among animal groups are used to study evolutionary relationships within the animal clade.-Derived traits are found in fossils, developmental patterns, morphology & physiology & genome sequences. Embryonic Development: Patterns of embryonic development were traditionally used to study animal phylogeny. Cleavage Patterns: first few divisions of the zygote; distinguish some animal groups....
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