BGEN 3020 Lecture Notes - Lecture 12: Xist (Gene), Klinefelter Syndrome, Single Transverse Palmar Crease
3 Oct 2018
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Document Summary
Mitotic non-dysjunction and mosaicism can occur with chromosome 21, and the x chromosomes. One daughter cell is missing some chromosomes, the other has too many. Non-balanced distribution of genetic material: non-dysjunction in meiosis. Meiotic non-dysjunction acrocentric chromosomes seen above the centromere is near the top of the chromosome. Xist: x-inactive-specific-transcript: makes mrna that coats the x chromosome to inactivate it, active on the inactive x chromosome, inactive on the active x chromosome. Pseudoautosomal region is located at the very tip of the x p-arm and the y p-arm: pairing occurs between the x and y chromosomes only at this region. Genes in the par1 region: shox gene stature homeobox, responsible for stature (i. e. height, sry gene, located just part the par region in the p-arm i. e. not actually in the par region. Par2 region located at the bottom of the x and y chromosomes: sometimes pairs, sometimes doesn"t, sometimes present, sometimes absent thought to be a variant.
