PSY 220 Lecture Notes - Lecture 3: Twin, Malnutrition, Zygosity
6 Mar 2017
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Document Summary
Dizygotic twins: fraternal, 1:125 births, siblings born at the same time. Unaffected by the environment or individual: genotype: all the genes a person inherits, gene for tallness or shortness, phenotype: the observable expression of genes, environment: impacts phenotype, actual height person grows. Single gene cause: polygenic transmission (cancer risk, height, iq, etc. ) Allele: variant of a gene (eye color gene can be brown or blue: homozygous, heterozygous. Recessive gene on the x 23rd chromosome (sex chromosome) Males x, y no dominant counterpart: color blindness, hemophilia. Change in chemical structure of one or more genes that can (or not) result in a new phenotype. Can be induced by errors in replication as well as environmental hazards (radiation, chemicals) Can be problematic or beneficial: sickle cell malaria, disease common in african americans, may have been adaptive in tropical regions because it helped in protect from malaria. Hereditability estimate: extent to which individual difference are due to genetic disorders.
