PSY 240 1st Edition Lecture 4Developmental PsychologyLecture Outline #3: Biology and Behavior – Genetics-Nature vs Nurture or Nature through nurtureHistory of Genetics Research- Gregor Mendel: 1866 Characteristics of pea plants passed from one generation to next. - Francis Galton: inspired by Darwin eugenics (sterilization, genocide): improving genetics, or things to improve the human genes. - Francis Crick & James Watson: 1953: Discover structure of DNA- Human Genome Project: 2003: completiono Far fewer genes in genome than previously thought (20,000)o Genetic similarity within/between speciesBasics of Genetics- genotype: genetic material an individual inherits- phenotype: observable expression of genotype (physical, behavioral)- chromosome: molecules of DNA in cell nucleus (46 chromosomes, 23 pairs)o DNA (deoxyribonucleic acid): molecules that contain biochemical instructions for formation, functioning of persono genes: sections of chromosomes, DNA “packets” (only 2% of genome)Studying Genetics- molecular genetics: identification of particular genes, functioning within cell- behavioral genetics: determine degree of genetic basis for behavior/trait/ability vs. environment (ex. Adoptive children)- behavioral genomics: links behavior with specific genes o -bridge between molecular and behavioral geneticsHow Genes Work- sperm + egg= 23 pairs of chromosomeso 23rd determines gender women: XX men: XY sperm cell (X or Y) genderdizygotic vs. monozygotic twins:- DZ:2 eggs released by mother, both conceived independently “Fraternal twins”-share 50% of genes (like any other siblings)-don’t need to share sex-age factors- MZ: monozygotic twins: 1 conceived zygote splits in half “Identical twins”-100% genetically identical-always same sexHow Genes Work-DNAgenes chromosomes4 protein bases to DNA: guanine (G), adenine (A), thymine (T), cytosine (C)dominant vs. recessive genes: both in genotypedominant: phenotyperecessive: usually dominant gene over recessivee.g. brown eyes vs. blue eyes-brown eyes (B) dominant, blue eyes (b) recessive-If mother=brown eyes (BB), father= blue eyes (bb)polygenic inheritance:3 Types of Genetic Disorders1. single gene disorders: a. sinkle-cell anemia: distortion to red blood cell shapei. worse oxygen distribution, hard clumping blocking blood flowb. Tay Sachs disease: inability to process dietary proteinsc. Phenylketonuria (PKU): inability to digest certain amino acidsd. Cystic fibrosisGenes & Behavior-voles: prairie vole mates for life, meadow vole does not-Prairie: vasopressin hormone released during sex (basis for love)-switch single vasopressin producing gene switch mating behavior-polygenic inheritance: multiple genes likely responsible for many behaviors3 Types of Genetic Disordersmutations: changes in gene formation during mitosis-most genetic disorders recessive genes-usually protected by paired dominant gene-XY pairing problems: -X: 900-1400 genes Y: 70-200-not all X genes find Y partner will be expressed whether dominant or recessive-males: increased risk for X chromosome related disorders-red-green color blindness, muscular dystrophy, hemophilia2. chromosome disorders “breakage”Down syndrome (aka. trisomy 21): one of 23 pairs has 1 or 3 chromosomes, not 2symptoms: heart, eye & ear defects, sleep apnea, poor muscle tone-sloping forehead, short limbs, flattened nose, almond-shaped eyes-Intellectual disability: avg. IQ= 50-55avg. life expectancy=49 (neurodegenerative disease)3. multifactorial inheritance disordersa. genetic component, but also interaction with environment-eg. Depression, alcoholism, schizophrenia, autismAutism autism spectrum disorder: brain development disorder, typically evident from infancyo 1-2 per 1000 birthso 4-5x as common in men3 classes of autism symptoms:1. social interaction impairments “impaired theory of mind”-can understand others’ basic goals & intentions, but difficulty understanding complex social emotions and considering others’ viewpoints-little eye contact, smiling-unlikely to spontaneously approach others-little nonverbal communication, emotional exchange-does not mean a preference for solitude-form attachments 2. Communication impairments: delayed onset of babbling-decreased responsiveness-echolalia-difficulty understanding pointing3.repetitive behaviors-stereotypy-sameness-restricted behavior-self-injury (30%)-compulsive behaviors (patterns, repetition, organization)potential causes of autism: we don’t know but…-Autism might not be one thing-multiple aspects with independent causes that often co-occur?epigenetics: system by which genes are activated/silenced by environment-genome doesn’t change, but expression