BI226 Lecture Notes - Lecture 31: Robertsonian Translocation, Centromere, Chromosomal Rearrangement
Document Summary
Robertsonian translocations can reshape genomes: arise from breaks at or near centromeres of two acrocentric chromosomes, the small chromosome may be lost from the organism, only occurs between 2 acrocentric chromosomes (centromeres near the ends) Human evolution: apes are 2n=48, while humans are 2n=46. It is thought that chromosomes #12 and #13 (both acrocentric) fused sometime early during human evolution after our separation from our last common ancestor with the apes: this fusion formed our chromosome #2. Down syndrome arising from a robertsonian translocation between chromosomes 21 and 14. Syndrome comes up at higher rate than normal in families of ppl with downs syndrome robertsonian fusionone 14, one 21, one fusion chromosome (phenotypically normal) During meiosisfusion goes to metaphase plate as 1 unit2 goes to 1 pole, 1 goes to other pole. 6 diff gametes - 142121 (downs syndrome) 141421 (inviable)
