notes DEVELOPMENT - DEVELOPMENT - HOW does a cell become...

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DEVELOPMENT -- HOW does a cell become differentiated? Basically there should be three lectures: I. the events of Fertilization Cleavage Gastrulation Organogenesis II. the influence of cytoplasmic determinants (factors) Factors that are unevenly distributed in egg, so that after first cell division, one cell has higher concentration than the other, III. induction of specific differentiation via cell-cell interactions One cell induces its neighbor(s) to change BOTH II and III above involve the use of transcription factors - that bind to DNA and turn on ( or off) the expression of some genes. This requires knowing Chapter 18 material, so we will insert a lecture on Chapter 18 between lectures I and II. WHAT about Stem cells and Cloning? Where do stem cells come from? “Adult” vs embryonic stem cells. “Therapeutic” vs “reproductive” cloning. I. Early events Four main stages discussed (book p446-451), p 455, p 457, figs 21.1, 21.3, 21.4 21.5, 21.6, and 21.23 (skip Arabidopsis and Drosophila) A. Fertilization Acrosomal reaction – release of enzymes from sperm to digest the gel protecting the egg Cortical reaction - Fast and slow block of polyspermy: Fast block is a rapid change (milliseconds) in electrical potential of the cell. Slow block involves calcium- induced changes in the cell and cell membrane that forms a physical block to second sperm – cortical reaction releases cortical vesicles with enzymes, that degrade sperm receptors (bindin protein) on the outside of the membrane fig 21.5, among other things, and other molecules ( that increase osmolarity and aid in formation of fertilization envelope, fig 21.6b ) Note, exocytosis of vesicles is usually triggered by raising Ca++ in cells, which fits in nicely with fig 21.6a. B.
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This note was uploaded on 04/29/2008 for the course BIOS 100 taught by Professor Kelso during the Spring '07 term at Ill. Chicago.

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notes DEVELOPMENT - DEVELOPMENT - HOW does a cell become...

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