Professor Smalls Lecture 19.docx - Professor Smalls Lecture 19[Gene Regulation in Development The process of cellular differentiation happens through 2

Professor Smalls Lecture 19.docx - Professor Smalls Lecture...

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Professor Smalls Lecture 19 [Gene Regulation in Development]: The process of cellular differentiation happens through 2 processes: Asymmetric division and cell-cell communication . Cells resulting from mitotic division can be a little bit or a lot different from each other. Cell-cell communication involves secretion of molecular signals; differentiation occurs because often, the receiving cell is different from the signaling one. Cellular differentiation occurs right after fertilization. Asymmetric Cell Division: All the cytoplasm of the zygote, comes from the egg. So the first parts of development are controlled entirely by the mom. The contents of the mother’s egg include proteins for mitosis, mitochondria, cytoskeletal components, and patterning information (determinants) for embryonic development. In general, cytoplasm is not homogenous. Asymmetric Cell Division in C. elegans: C. elegans (a free living roundworm that feeds on bacteria, with a life cycle at 3.5 days at 20 degrees Celsius) is the model system we use for development. The question to ask is how we really know if the two daughter cells after the first mitotic division (following fertilization) of C. elegans different. This is proven by the fact that P-Granules (cytoplasmic determinants) are sequestered into only one of the two daughter cells, therefore proving that the cytoplasm of two daughter cells are different. The first division in human cells isn’t asymmetric. Every once in a while, twins arise from the fact that cells somehow separated following mitotic division after fertilization, but can still undergo the whole process again just fine.
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  • Fall '15
  • Eric Martin
  • DNA, Bicoid

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