BIOL 3409- Midterm Exam Guide - Comprehensive Notes for the exam ( 65 pages long!)
5 Oct 2017
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Document Summary
Genomic integrity: stability in sequence and structure, accomplished by, protection of stem-cells (by two mechanisms): Stem-cells give rise to all other cells in a tissue/organ. Undergo relatively few mitosis and have limited life span. Protected from mutagenic agents physically and by distance. Have high expression of mdr1 = able to efficiently pump out dyes (toxins) Tissue organization and protection of the stem cell genome. Each stem-cell divides occasionally asymmetrically stem cell daughter + transit amplifying daughter: shielded anatomically from toxic agents. Transit-amplifying cells expand exponentially: products undergo differentiation into post-mitotic, highly differentiated cells. Stem-cells in bottom of crypts shielded from the contents of the small intestine by location and protective mucus. Give rise to all other cells travel up. Lose proliferative potential as they differentiate: stem cells = likely targets of mutagenesis that leads to cancer, evidence: several types of leukemia initial targets of carcinogenesis are stem cells.
