nps28F7 - Animal body plans and developmental patterns...

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Multicellular organisms -- plants and animals -- have the challenge of development . They have a life cycle with a unicellular stage (or stages). Typically for animals: adult gametes zygote (multicellular) (unicellular) (unicellular) embryo (developmental processes) Animal body plans and developmental patterns In typical animals, only the gametes are haploid -- no alteration between multicellular haploid and diploid life stages. Multicellular organisms -- plants and animals -- have the challenge of development . They have a life cycle with a unicellular stage (or stages). Typically for animals: adult gametes zygote (multicellular) (unicellular) (unicellular) embryo (developmental processes) Sexual adult unicellular gametes unicellular zygote one or more multicellular one or more multicellular asexual “larval” stages “embryonic” stages A more complex animal life cycle: Animal body plans and developmental patterns Another characteristic of multicellular organisms: Senescence (aging) Unicellular forms can often divide without limit Multicellular forms have limited life span (~115 years in humans) Zygote embryo juvenile adult senescence, death time Survival (% still alive) Animal body plans and developmental patterns age Sudden increase in adult mortality above a certain age Another characteristic of multicellular organisms: Senescence (aging) Unicellular forms can often divide without limit Multicellular forms have limited life span (~115 years in humans) Zygote embryo juvenile adult senescence, death time age Survival (% still alive) Running speed Disease resistance Fertility Animal body plans and developmental patterns
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Four basic developmental processes lead from unicellular zygote to adult: cell proliferation : more cells produced by cell divisions cell differentiation : cells change into various types (differing structurally, biochemically, etc.) for specialized functions -- but all have the same genetic information cell death (apoptosis): a programmed process that contributes to formation of body structures cell migration : embryonic cells move with respect to each other Animal body plans and developmental patterns These four processes create an enormous increase in complexity -- but no change in genetic information: Start as an undifferentiated single cell; finish as a very complex structure containing many types of cells arranged in precise ways. About 10 14 cells of ~100 types in humans, for example. Developmental biology is key to understanding animal diversity and the overall body ‘plan’ of an organism. The body plan is specified by four fundamental properties established during development • these are also crucial traits that differentiate major phyla. Animal body plans and developmental patterns 1.
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This note was uploaded on 04/03/2010 for the course BIO Bio 5b taught by Professor Chappel/douhan during the Winter '10 term at UC Riverside.

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nps28F7 - Animal body plans and developmental patterns...

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