psy 120 - Biological Processes PSY 120 120 Prof. South...

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1 Biological Processes PSY 120 Prof. South 1/25/11 & 1/27/11 Biological Basis of Behavior 1. Theory of Evolution 2. Genes 3. Nervous system 4. Brain structure and function 1. Evolution
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2 Basic idea of Evolution Modern forms of life came about through gradual changes from earlier forms Darwin’s Contribution Mechanism for evolution: Natural selection “Owning to this struggle (for life), variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings and to their physical conditions of life, will tend to the preservation of such individuals, and will generally be inherited by the offspring” (Darwin, 1859, p 51-52) Darwin’s Theory of Natural Selection 1. All living species arrived at their present biological structures through a historical process involving random inherited changes 2 Those changes that enhanced an 2. Those changes that enhanced an organism’s ability to survive and reproduce were passed along in increasing numbers from generation to generation 3. Those changes that hindered survival and reproduction were lost over generations
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3 Adaptation • A trait selected for by nature b/c it increases reproductive “fitness” • Must be: – Universal – Economical – Adaptive How are changes passed from generation to generation? Darwin did not know the mechanism 20 th century discovery - DNA and genes GENES are the biological units of heredity 2. Genes
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4 Chromosomal abnormalities • Many are sex-linked – Turner syndrome: only 1 X chromosome – Fragile X • Autosomal anomalies – Down’s syndrome Genetic effects • Genes • Heterozygous vs. homozygous – Alleles • Dominant vs recessive
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5 bb B Bb Bb Mother – Blue eyes (bb) Brown Brown b bb Blue bb Blue Father Brown Eyes (Bb) Genotype: The set of genes that an individual inherits Phenotype: Observable properties of the body and behavioral traits Genetic effects • Single gene effects – Huntington’s disease (HD): chromosome 4 – Phenylketonuria (PKU)
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6 Dominant vs. recessive inheritance Genetic effects • Polygenic effects – Effect of many genes – Example: schizophrenia Why are there harmful genes?
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This note was uploaded on 02/19/2011 for the course PSY 120 taught by Professor Donnely during the Spring '08 term at Purdue.

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psy 120 - Biological Processes PSY 120 120 Prof. South...

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