HO-23 - BIO 320 lecture 23 All Reading Ch 20 Problems text 20.1-5 17-19 21-22 Question bank E Gene expression and development Stages of

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Determination : establishing cell identity. Some signals that determine cell identity: All cells in an embryo arise by mitotic division from a single-celled zygote, and have the same set of genes - the genome is constant through development. Zygote : a fertilized oocyte pronuclei Blastula : many undifferentiated cells in a single layer Stages of development (in a lower vertebrate) Gene expression and development BIO 320 Reading: Ch 20, lecture 23 Problems: text 20.1-5; 17-19; During development, cells can. ..: Migrate: cells can move singly or in groups over long distances. They may be guided by other "signpost" cells or by molecules of the extracellular matrix. Commit suicide: some cells are fated for programmed cell death ; this may happen in order to create a gap - e.g. between fingers. Proliferate : several rounds of cell division usually begin development. This occurs without growth or new protein synthesis; enough proteins and mRNAs are stored in the oocyte. Some stem cells continue to divide into adulthood - e.g., to a maintain a supply of new blood cells. . Change shape : cell layers can fold and bulge when the cells pinch in to a wedge shape Stick selectively to one another : different cell types express different classes of cell adhesion molecules on their surfaces: cells with a similar CAM will tend to stay together, or sort out from a mixture. Even while cells are still dividing and appear identical to one another, they may already be determined. This means that their developmental options have been limited to a subset of fates - e.g., head only, or eye only. At the gene level, determination corresponds to a new stable state of gene regulation. Determinants
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This note was uploaded on 06/03/2008 for the course BIO 320 taught by Professor N/a during the Spring '08 term at SUNY Stony Brook.

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HO-23 - BIO 320 lecture 23 All Reading Ch 20 Problems text 20.1-5 17-19 21-22 Question bank E Gene expression and development Stages of

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