BSCI 222 Lecture Notes - Lecture 8: Metaphase
25 Sep 2015
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Bsci 222 - lecture 08 - chromosome variation. Telomere repeat probe - telomere stained with fluorescent labels/probes. Extra genes/deficit of copies of a gene. 1% of genes undergo duplication every million years. Half life of duplicated gene is appx. Can occur due to an unequal crossover: Segment of chromosome is turned 180 degrees. Segment of chromosome moves from one chromosome to a nonhomologous chromosome, or to another place on the same chromosome. Imbalance in gene expression relative to other genes in organism. Cells undergo repeated rounds of dna replication without undergoing cell division. Multiple rounds of this produce many sister chromatids that remain synapsed together. The increases in cell volume ---> formation of polytene chromosomes. Doesn"t change the number of copies of the gene, but it often changes the local gene environment. Some environments are less condensed or more condensed. Moving genes to a different environment can lead to alterations in the gene expression pattern.
