Psychology 2410A/B Chapter 3: Chapter 3 - Introduction to Developmental Psychology

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Directly observable characteristics are called phenotypes; they depend in part on the individual"s genotype - the complex blend of genetic information that determines our species and influences all our unique characteristics. Dna along the length of the chromosome; genes can be of different lengths. Between 98 and 99 percent of chimpanzee and human dna is identical; individuals around the world are about 99. 1 percent genetically identical. Mutation - mutation - a sudden but permanent change in a segment of dna. Polygenic inheritance - polygenic inheritance - many genes determine the characteristic in question; polygenic inheritance is complex, and much about it is still unknown. Most chromosomal defects result from mistakes occuring during meiosis, when the ovum and sperm are formed. Most children with sex chromosome disorders do not suffer from mental retardation; instead, their intellectual problems are usually very specific.