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TAMU PSYC 307 - Biological Backgrounds of Developmental Psychology
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PSYC 307 1st Edition Lecture 3Overview of Previous LectureI. Research MethodsOverview of Current Lecture: II. Biological Backgroundsa. Interplay of Heredity and Environmentb. Allelesc. Model of Interactiond. Behavior Geneticse. Prenatal Development Current Lecture: Biological Backgrounds I. Interplay of Heredity and Environmenti. Influences individual’s characterb. Basic Genetics Principlesi. Two kinds of cells1. Somatic: body cells (23 pairs of chromosomes)a. Cell division by mitosisb. 23rd pair = sex chromosomes (determine gender)c. Genes: segments of chromosomes, units of heredity 2. Gametes: sex cells; sperm, ovum (23 single chromosomes)a. Cell division by meiosis b. When cells divide, they split chromosome pairs into singlesc. Twinningi. Identical (monozygotic): share the same DNA, one fertilized egg splits into two ii. Fraternal (dizygotic): two separate eggs are fertilized; different DNA1. Fraternal twins share 50% of their genetic materiala. Same as siblings born at different timesiii. Half identical: one egg, two different sperm1. The egg splits after fertilization 2. Most rare of the types of twinning iv. Other factors effecting twinning1. Ethnic factors: twins occur the most frequently in whites, less frequently in blacks, least frequently in Asians2. Incidence of twins in relation to age: women between the ages of 35 and 39 have the highest likelihood to give birth to twins 3. Nutrition and body type: women with small, slight builds are less likely to have twins; women with poor nutrition and diet are less likely to have twins d. Mechanisms and Genetic Diversity i. Mutations: irregularities in genesii. Random Assortment: cells split randomly, no set structure to cell division iii. Cross-over: parts of chromosomes or DNA can break off and attach somewhere else, or to a different piece of genetic material entirely II. Alleles i. Two forms of alleles 1. Dominant (expressed): only one dominant allele needed for the trait to be expressed2. Recessive: only expressed if two recessive alleles are present a. Can be a carrier of the trait without expressing it b. Single Gene Transmissioni. Expression of traits as a combination from mother and fatherc. X-Linked Inheritancei. Occurs more likely in boys ii. X-chromosome recessive gene (from mother)1. No chance to have an X-chromosome dominant (XY)2. Color blindness, hemophilia, muscular dystrophyd. Polygenic Inheritance i. Several genes required to produce a trait ii. 5000+ diseases/disorders known to have genetic origins1. Errors in meiosis: genes do not split correctlya. Trisomy 21: Down’s Syndrome (3 chromosomes on the 21stpair)2. Recessive3. Single dominant4. Sex-linked abnormalitya. Malesi. Kleinfelter’s Syndrome (XXY)1. Secondary sex hormones do not develop a. Testosterone used to treat: can lead to sterility 2. Shy, low self-esteem (social implications)a. Look feminine3. Occurrence 1/1000ii. XYY syndrome (phenotypically normal)1. Accelerated growth; average height above age group2. Learning difficulties are possible3. Studies show there are more XYY males in prisons than outside of prison (put away for nonviolent crimes)4. Occurrence 1/1000b. Femalesi. Turner’s syndrome (XO) 1. No second chromosome on 23rd pair 2. No secondary sex characteristicsa. Usually sterile3. Higher than average special cognition 4. Shorter, broad chested, neck webbing, low ears 5. Occurrence 1/2000ii. XXX Syndrome1. Normal physical and sexual development c. These conditions are rarely known to those who have them because few people know their karyoteIII. Model of Interaction a. Key elementsi. Genotype: set of genes you carry (not all are expressed)ii. Environment: what is happening around usiii. Phenotype: expression of genes 1. Can depend on environment/experience b. Fundamental Relations i. Parent’s Genotype  Child’s Genotype  Child’s Phenotype  Child’s Environment1. Parent’s genotype can also affect the child’s environment a. Affected by habits, traits, etc. of parent c. Model of Interaction i. Canalization: behaviors are largely determined by genes1. Environment has little to no influence a. Ie: you environment cannot change your physical reflexes to things ii. Range of reaction: genes provide possibilities, environment can affect intellectual function iii. Gene environmental correlations: Sandra Scar1. Passive: take in the environment they are given2. Evocative (reactive): evoke particular reactions 3. Active: pick own environment (adolescence  adulthood)iv. Niche-picking: pick type of environment in which we are most comfortable d. Gene Environment Interaction – PKUi. Phenylketonuria – chromosome 12 defective ii. Unable to metabolize phenylalanine 1. If untreated, can result in severe retardation2. Early diagnosis/treatment: outcome positive IV. Behavior Genetics a. Traits of interest are multifactoriali. Affected by many environmental/genetic factorsb. Methods of studyi. Family trees (plot what is being passed between generations)1. Takes decades to collect data2. Not all data is recorded and available across time ii. Twin studies: identical vs. fraternal trait comparison1. Common in comparing IQ and the effect of environment iii. Adoption studies: individuals that share genetic material but do not share environment iv. Human Genome Project: traits linked to specific genesV. Prenatal Diagnostic Method a. Genetic counseling: trait and genetic history of parentsb. Amniocentisis: through abdomen into amniotic sac and pull out amniotic fluid i. Between 12-18 weeks, post-conception ii. Risk of amniotic sac not healing (lose sac and therefore baby)iii. Gives genetic information about the fetusc. Chorionic villus sampling i. 8-12 weeks post-conception d. Ultrasound: gives information about structure of fetusi. Can identify structural abnormalities 1. Down’s, heart conditions, crown to rump measurement2. Does not give any genetic information e. Maternal blood analysisi. 14-20 weeks1. Very invasive2. Levels of fetal proteins in blood can be markers for risks for fetusf. Fetoscopy: light inserted to get pictures of structure of


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TAMU PSYC 307 - Biological Backgrounds of Developmental Psychology

Type: Lecture Note
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