PSYC 307 1st Edition Le cture 3 Overview of Previous Lecture I Research Methods Overview of Current Lecture II Biological Backgrounds a Interplay of Heredity and Environment b Alleles c Model of Interaction d Behavior Genetics e Prenatal Development Current Lecture Biological Backgrounds I Interplay of Heredity and Environment i Influences individual s character b Basic Genetics Principles i Two kinds of cells 1 Somatic body cells 23 pairs of chromosomes a Cell division by mitosis b 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 singles c Twinning i Identical monozygotic share the same DNA one fertilized egg splits into two ii Fraternal dizygotic two separate eggs are fertilized different DNA 1 Fraternal twins share 50 of their genetic material a Same as siblings born at different times iii Half identical one egg two different sperm 1 The egg splits after fertilization 2 Most rare of the types of twinning iv Other factors effecting twinning 1 Ethnic factors twins occur the most frequently in whites less frequently in blacks least frequently in Asians 2 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 genes ii 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 expressed 2 Recessive only expressed if two recessive alleles are present a Can be a carrier of the trait without expressing it b Single Gene Transmission i Expression of traits as a combination from mother and father c X Linked Inheritance i 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 dystrophy d Polygenic Inheritance i Several genes required to produce a trait ii 5000 diseases disorders known to have genetic origins 1 Errors in meiosis genes do not split correctly a Trisomy 21 Down s Syndrome 3 chromosomes on the 21st pair 2 Recessive 3 Single dominant 4 Sex linked abnormality a Males i 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 feminine 3 Occurrence 1 1000 ii XYY syndrome phenotypically normal 1 Accelerated growth average height above age group 2 Learning difficulties are possible 3 Studies show there are more XYY males in prisons than outside of prison put away for nonviolent crimes 4 Occurrence 1 1000 b Females i Turner s syndrome XO 1 No second chromosome on 23rd pair 2 No secondary sex characteristics a Usually sterile 3 Higher than average special cognition 4 Shorter broad chested neck webbing low ears 5 Occurrence 1 2000 ii XXX Syndrome 1 Normal physical and sexual development c These conditions are rarely known to those who have them because few people know their karyote III Model of Interaction a Key elements i Genotype set of genes you carry not all are expressed ii Environment what is happening around us iii 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 Environment 1 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 genes 1 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 Scar 1 Passive take in the environment they are given 2 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 PKU i Phenylketonuria chromosome 12 defective ii Unable to metabolize phenylalanine 1 If untreated can result in severe retardation 2 Early diagnosis treatment outcome positive IV Behavior Genetics a Traits of interest are multifactorial i Affected by many environmental genetic factors b Methods of study i Family trees plot what is being passed between generations 1 Takes decades to collect data 2 Not all data is recorded and available across time ii Twin studies identical vs fraternal trait comparison 1 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 genes V Prenatal Diagnostic Method a Genetic counseling trait and genetic history of parents b 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 fetus c Chorionic villus sampling i 8 12 weeks post conception d Ultrasound gives information about structure of fetus i Can identify structural abnormalities 1 Down s heart conditions crown to rump measurement 2 Does not give any genetic information e Maternal blood analysis i 14 20 weeks 1 Very invasive 2 Levels of fetal proteins in blood can be markers for risks for fetus f Fetoscopy light inserted to get pictures of structure of fetus
View Full Document
Unlocking...