BIOLOGY 171 Chapter Notes - Chapter 14.3, 17.4: Globin, Molecular Clock, Fetus
25 Mar 2017
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Reading #25- 14. 3, 17. 4: duplication, deletions, and gene families. Duplications and deletions result in a gain or loss of dna (also most common abnormalities) Duplications are when a chromosome has a region that is presented in two copies instead of 1: large duplications that are harmful are usually eliminated, small duplications can be maintained over generations, usually less harmful than deletions. Dosage is the number of copies of each gene in a chromosome; normal embryonic development requires genes to be present in the correct dosage. On rarely sees deletions of duplications that include the centromere because abnormal chromosomes without centromeres are usually lost within a few cells divisions. Gene families arise from gene duplication and evolutionary divergence. In most cases, when a gene is duplicated, one copy is free to change without causing damage because the other copy continues to carry out normal function of the gene.
