Child Psychology 560 Biological Foundations 1 Prenatal Development Key Vocabulary Typical cells 46 chromosomes each 23 pairs Gametes 23 chromosomes each o o Created via meiosis Sperm and egg also called germ cells Each gamete parent cell s set Gametes combine to create zygote Zygote 1 cells o o 46 chromosomes 23 pairs Each contains 21 000 genes Growth of zygote Mitosis o New cells via duplication and division Genetic diversity Meiosis zygote differs from each parent Crossing over DNA exchanged between paired chromosomes during meiosis Mutations Change in a section of DNA Multiple births Identical twins 01 23 2014 o o o o Cell mass separates during early mitosis Same genetic code to start out with Monozygotic MZ one zygote zygote splits in 2 1 in 250 live births Fraternal twins o o o o 2 sperm 2 eggs at the same time Dizygotic DZ 2 separate zygotes 1 in 30 live births 74 increase 1980 2000 Why Fertility treatments prospective mother will take medication to allow her to have more eggs Studying gene behavior relationships 1 Twin studies o o Twins allow us to keep genes constant while manipulating the environment E g Plomin Defries 1985 Temperament MZ share all genes vs DZ twins share some genes Emotionally sociability Results MZ Concordance rate correlation 55 DZ Concordance rate 0 Genetic basis Since they share the same environment o twins also share some genes If MZ DZ does that mean that the trait is genetic E g MZ correlation 70 AND DZ correlation 70 o o o Some genetics are going on since there is some correlation but DZ You would assume they are genetic but it tells you its not because MZ shares more genes than the DZ twins In twin studies you need to compare twins that share all of their genes MZ versus twins that only share some DZ Most traits follow polygenetic inheritance multiple genes involved so few behaviors are going to be a result of any single gene Example of heritability trait ASD example MZ twins are twice as likely to share an autism diagnosis than DZ twins At present more than 100 candidate genes for ASD It would be accurate to say it has heritable components but inaccurate to say that a single or only a few genes cause ASD 2 Genetic atypicalities o 2 1 Recessive Mutations change in a gene or gene sequence Half of all conceptions genetic abnormalities 45 of pregnancies end before woman know they are actually present usually due to mutations 1 5 woman of childbearing age will have pregnancies that will end with their knowledge 3 5 live births genetic abnormality Usually recessive not expressed Recessive Inheritance Punnett square Dd x Dd DD Dd Dd dd Example Sickle cell anemia Affects 1 in 400 African Americans If gene from both parents homozygous o o Shouldn t the mutation die out o o Incidence very low in U S But in West Africa incidence 20 Mutation can be adaptive o o Abnormal blood clotting Can be fatal If gene is inherited from only one parent heterozygous Promotes resistance to malaria 2 2 Sex linked X linked recessive genetic defect predominantly expressed in male infants than female infants o Sex linked genetic defects Color blindness Hemophilia Some forms of muscular dystrophy Some forms of deafness 2 3 Non inherited mutations Too many or too few chromosomes Example Down syndrome trisomy 21 47 chromosomes Physical effects Heart lung ear problems Susceptible to leukemia Cognitive delays IQ 50 range High risk for depression Incidence USA don t need to know numbers just to get an idea of them 1 in 600 live births o Strong relationship with mom s age o o At 20 1 in 1 900 By 49 1 in 12 Why does mom s age matter o o o 1 in 150 conceptions Born with all of our eggs Ova susceptible to environmental damage viruses radiation chemicals Older eggs exposure to toxins Dad s age matter too Non genetic effects on prenatal development Maternal emotions o Coe research UW Prenatal stress newborn iron deficiency immune suppression o O Connor et al 2002 More distress during pregnancy Lead to more behavioral problems at age 4 confounds Confounds na ve to believe the woman won t still be stressed once the child is born Maternal Nutrition Famine o Holland 1944 1945 during WWII More still births malformations and deaths at birth Lower birth weights Timing early malnutrition worse than late Maternal Nutrition Poverty o WIC begun in 1972 food vouchers 2010 10 million women infants children Lower health problems improve infant mortality Timing of WIC matters Cognitive development at age 6 WIC in last trimester WIC after birth Teratogens Environmental agents of birth defects o Legal teratogens 60 of U S pregnant women take something caffeine alcohol 15 20 cigarettes 11 Varied effects from low birth weight to intellectual impairments Accutane prescription medication for acne Sensitive periods pg 60 in textbook Severe deficits can occur early on Fetal Development Sonogram video of fetuses at different ages Fetal Sensory Capacities Motion o Vestibular system at 5 months o o allows us to know if we are up down etc Fully developed by birth Can sense changes in mom s posture Vision o At 26 weeks light heart rate changes o Birth Nearsighted Actively scanning Audition o o End of 2nd trimester Average sound level 75 Db Air passing through mom s stomach Heartbeat o Mom s speech heard best Heart rate changes Other fetal behaviors o Movement from 5 6 weeks Hiccuping Backwards somersaults By 12 weeks full repertoire of movement Less activity with age sleep maybe of the time o More active fetuses more active neonates o Swallowing breathing 01 23 2014 01 23 2014