developmentalbioreadingnotes

developmentalbioreadingnotes - Reading notes: 1-16 - every...

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Reading notes: 1-16 - every animal function as it builds itself - differentiation – hundreds of different cell types - 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 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 - create 3 germ layers that will interact to create organs - organogenesis – cell interact and rearrange themselves to produce tissues and organs - many organs have cells that come from more than 1 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 – divide rapidly and become rapidly mobile - blastocoel (fluid-filled cavity) forms during cleavage - gastrulation occurs at 180 degrees 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 - mesoderm 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 – meiosis diagram - chromosomes replicate prior to cell division, so each gene represented 4 times - replicated chromosomes (each called a chromatid) held together by kinetochores (centromeres) and the 4 homologous chromatids pair together - 1 st meiotic division separates chromatid pairs from one another - 2 nd meiotic division splits kinetochore such that each chromatid becomes a chromosome - result is 4 germ cells, each with a haploid nucleus - comparative embryology – study of how anatomy changes during development different organisms - oviparity – born from eggs - viviparity – live birth - ovoiviparity – produce an egg that hatches inside body - cell divisions - holoblastic – entire egg divided into smaller cells - meroblastic – only part of egg becomes embryo - triploblastic – 3 layers; ectoderm, mesoderm, endoderm - diploblastic – 2 layers; lack true mesoderm; sponges, comb jellies
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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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developmentalbioreadingnotes - Reading notes: 1-16 - every...

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