470readingnotesexam1 - notes pg 1-16 - every animal must...

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notes pg 1-16 - every animal must function as it builds itself - differentiation – hundreds of different cell layers - morphogenesis – coordinating cell growth, migration, death; creation of ordered form - growth – regulation of cell division - regeneration – stem cells forming new structures - evolution – changes in development/environment to create new body forms - zygote – single cell, fertilized egg - developmental bio – discipline that studies embryonic and other developmental processes - cycle of life - fertilization – fusion of gametes (sperm and egg) and gamete nuclei (creates genome) - cleavage – series of rapid mitotic divisions - zygote cytoplasm divided into smaller cells called blastomeres - at end sphere formed, called blastula - gastrulation – series of extensive cell rearrangements – creates 3 germ layers that will interact to create origins - organogenesis – cells interact and rearrange themselves to produce tissue and organs - many organs have cells that come from more than one germ layer - cells undergo long migrations from place of origin to final location - metamorphosis (larval stage) – usually long stage to become sexually mature adult - germ cells – gametes and precursor cells gametogenesis – complete at physical maturity - somatic cells – all other cells of body - frog’s life - vegetal hemisphere (yolk) – bottom of egg, serves as food for embryo - animal hemisphere – upper half – divides rapidly and becomes rapidly mobile - blastocoel (fluid-filled cavity) – forms during cleavage - gastrulation occurs at 180 degrees where sperm entered – forms dimple called blastopore - organogenesis – begins when rod of mesodermal cells in most dorsal portion of embryo (notochord) signal ectodermal cells that they are not going to become epidermis become nervous system - neural precursor cells elongate, stretch, and fold into embryo, form neural tube - mesodermal tissue becomes segmented into somites - metamorphosis in amphibians initiated by hormones in thyroid - speed regulated by environmental pressures - to become mature, germ cells must be competent to complete meiosis - meiosis (DIAGRAM pg 10-11) - chromosomes replicate prior to cell division, so each gene is represented four times - replicated chromosomes (each called a chromatid) held together by kinetochores (centromeres), and the four homologous chromatids pair together - first meiotic division separates chromatid pairs from one another - second meiotic division splits kinetochore such that each chromatid becomes a chromosome - result is four germ cells, each with a haploid nucleus - comparative embryology – study of how anatomy changes during development of different organisms - oviparity – born from eggs - viviparity – live birth - ovovivparity – produce an egg that hatches inside body - cell divisions - holoblastic – entire egg divided into smaller cells - meroblastic – only part of egg becomes embryo - triplobasltic – three layers; ectoderm, mesoderm, endoderm
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This note was uploaded on 02/29/2012 for the course ZOOLOGY 470 taught by Professor Hardin during the Spring '12 term at Wisconsin.

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470readingnotesexam1 - notes pg 1-16 - every animal must...

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