BIOS10162 Lecture Notes - Lecture 4: Limb Development, Paracrine Signalling, Pattern Formation
31 Aug 2016
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Multicellular organism goes through a series of changes successive forms that characterize its life cycle. Embryo: earliest stages of development after fertilization. Cell fate influenced by changes in gene expression and environment. 2: differentiation- different types of cells arise = specificity in structure & function. 3: morphogenesis- organisation and spatial distribution of differentiated cells. Plants: zygote, embryo, globular embryo, heart embryo, torpedo embryo, adult plant. Can grow throughout life or reach a stable point. Experiment with early frog embryo (rear and front end switched)// timing of when it was switched determination is a commitment! Unequally distributed cytoplasmic determinants during cell division => polarity & differentiation (example: 8-cell sea urchin embryo) Polarity: distinct top and bottom ends (animal & vegetal pole in developing animals) A factor is actively produced and secreted by certain cells. Cytoplasmic determinants: specific proteins, regulatory rna, mrna. Cytoskeleton asymmetric distribution of cytoplasmic determinants (microtubules have polarity, motor proteins transport.
