INTRO TO DEVELOPMENTAL PSYCH
INTRO TO DEVELOPMENTAL PSYCH PSY 333D
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This 44 page Class Notes was uploaded by Marco Wolf on Monday September 7, 2015. The Class Notes belongs to PSY 333D at University of Texas at Austin taught by Staff in Fall. Since its upload, it has received 14 views. For similar materials see /class/181813/psy-333d-university-of-texas-at-austin in Psychlogy at University of Texas at Austin.
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Date Created: 09/07/15
The Genetics of Child Development l GENETIC FOUNDATIONS A The Genetic Code Chromosomes quotcolored bodiesquot carrying genetic material contained in the nucleus of all cells except red blood cells Humans have 23 pairs n 46 Chimpanzees have 24 pairs Horses have 32 pairs Mice have 20 pairs 2 Genes multiple genes per chromosome most genes lead to production of some protein Genes composed of 3 DNA deoxvribonucleic acid genes differ in length of the segments of DNA Double helix structure twisted ladder uncoiled set of 23 chromosomes would be 3 feet long in each cell Sides of ladder alternating sugar and phosphate molecules in two threads wound around each other Ladder rungs consist of pairs of nucleotides nitrogenbased molecules attached to the sugar units of the sides Adenine A paired with Thymine T Cytosine C with Guanine G sequence of pairings determines the genetic instructions chromosome 1 has 263 million bases smallest chrom 21 has 50 million bases Human Genome project 2 4 Kamotype depicts homologous pairs except for the XY pair in malesin humans 22 of the pairs are known as autosomes and l pair are chromosomes 5 Gametes sex cells egg sperm contain only 23 chromosomes each 6 Mitosis process by which DNA duplicates itself DNA ladder splits down the middle leaving each exposed base free to pick up its complementary mate from the cell cytoplasm sister chromatids attached at centromere then separate during cell division eg Zygoz e feltiized egg replicates in first 24 hours 7 Meiosis process by which gametes or sex cells are formed Cell with 46 chromosomes replicates itself but doesn39t split from sister chromosome Crossing Over pairs of chromosomes exhange corresponding segments to create new genetic combinations Cell then divides then divides again to leave 4 cells with 23 chromosomes each 8 Alleles the different formsversions of each gene eg Browneye blueeye greeneye etc occur at the same locus on the autosomes one each from mother and father 9 Genotyge one39s genetic inheritance eg BB or Bb or bb for eye color homozygous having same two alleles for a trait eg BB or bb heterozygous having two different alleles fora trait eg Bb 10 Phenotyge one39s expression ofa trait eg Brown eyes vs blue eyes 11 Monozvqotic Twins share a genotype mono one zygote dizygotic fraternal twins do not GENETIC INHERITANCE A Autosomes 1 Dominant Traits superoede expression of recessive traits 2 ReoessiveTraits Exhibited only when inherit two alleles only one allele makes one a carrier Dominant Recessive Brown eyes Gray green blue Curly hair Straight hair Brown hair blond or light hair Nonred hair BRbl Red hair thick lips thin lips dimples no dimples farsightedness normal vision Rhpositive blood Rhnegative blood 3 Codominance With some traits a combination of the alleles is phenotypically expressed as with AB blood Dominant Recessive Type A blood Type 0 Type B blood Type O 4 Polvqenic inheritance More than one gene influences expression of a trait such as intelligence and height 5 Dominant amp Recessive disorders a Dominant Huntinqton39s chorea occurs 3540 years of age causes brain deterioration loss of motor control memory personality etc Familial Alzheimer39s Marfan39s syndrome b Recessive Albinism Congenital deafness PKU or phenvlketonuria chrom 12 1 in I0000 births lack the ability for the liver to produce the enzyme phenylalanine hydroxylase that converts a amino acid phenylalanine into tyrosine toxic excess of phenylalanine builds up in nervous system leading to symptoms by 35 months death by 4 without dietary restrictions phenylalanine is amino acid in protein and is found in milk products eggs meat poultry legumes nuts wheat amp oats Galactosemia chr 9 17 1 depends on enzyme missing lack enzyme to convert galactose from lactose in milk into glucose Buildup in tissues causes mental retardation cataracts enlarged liver amp kidney failure Detection prenatally newborn Cystic Fibrosis chrom 7 most common genetic disease among Caucasians 1 in 3000 45 of Americans are carriers caused by a change in single nucleotide or one letter error respiratory tract becomes clogged with mucus increases risk of infection death by mid20s secretions also obstruct pancreas leading to dietary problems salty tasting skin TavSachs disease chrom 15 highest incidence in Ashkenazic Jews mental retardation blindness deafness and paralysis begin around 6 months of age death normally occurs by 34 years due to absence of an enzyme HexA HexosamindaseA which allows a lipid to accumulate in brain Sickle cell anemia chrom 11 incidence highest in AfricanAmericans caused a change in a single amino acid in hemoglobin which prevents some blood cells from carrying oxygen leading to a crescent shape owgen depletion from exercise plane cabins etc leads to painful sickling of blood cells Heterozygotes show protection from malaria 11 B Sexlinked Inheritance 1 Ylinked Inheritance Hairy ears 2 Xlinked Inheritance often recessive genes on Xchromosome Males have higher probability of phenotypic expression than females Redgreen color blindness Hemophilia detectable prenatally Duchenne muscular dystrophy LeschNvlan disease buildup of uric acid leads to accumulation of salt crystals in CNS joints kidneys recurrent vomiting cerebral palsy mental retardation selfmutilation amp death Fraqile X Svndrome a genetic disorder resulting in multiplication of part of genetic code resulting in a pinched long leg on the Xchromosome on long arm of X the triplet CAG replicated 2030 times if replicated over 50 times up to 200 leads to Fragile Xtype symptoms DeSale amp Lindey 1997 incidence in 1 in 1000 births a3 About Fra HEX 39 c g g 1 a most common genetic form of mental retardation facial deformities large ears prominentjaw long narrow face and large testes in males affected females may show reduced intelligence though most are normal possible link to infantile autism Food for thought Male fetuses are more likely than female fetuses to be aborted stillborn infant and childhood mortality is greater for males as is the rate of learning disabilities behavioral disorders and mental retardation This may be due to genetic disorders especialy Xlinked However a greater number of boys are conceived and there are l06 male births for every l00 females CHROMOSOMAL ABNORMALITIES Risk factors Advanced Maternal Age sometimes advanced Paternal age many caused by a glitch in meiosis httpgsc genetics utah eduunitsdisorderskaIyotype A Autosomal Abnormalities l Down39s Syndrome Trisomy 2 lncidence 1700 live births Physical features ipicanthal fold of eye flattened facial features poor muscle tone short stature and short broad hands with an unusual crease in palms excess skin on back of neck lnternal traits congenital heart defects cataractsvisual impairments deficiencies in immune system leading to susceptibility to infection and leukemia Shortened life expectancy those who live to over 35 typically develop the same neurophysiological and psychological symptoms as Alzheimer39s patients EC 2 3 ll x l ll s l ant at imt 37 if 3 Ef 21 22 xY 21 I t a 3 il l5 16 5 Cause failure of chromosome 2 to segregate during meiosis Down39s syndrome children show a mosaicism extra chromosomal material appears in only some cells degree of impairment related to number of cells affected Theories Older Egg vs Relaxed Selection hypotheses 2 Edward s Syndrome Trisomy 18 lncidence 150006000 live births predominantly females 1 tit 8090 o mortality rate by age 2 Severe mental retardation elfin facial features small nose amp mouth receding chin abnormal ears hearing loss seizures hypoglycemia I I I if r x 3 P Q 1 i l 1 2 3 4 5 d a V g a H 10 35 r a a 5 a t s 7 a a m n 42 u n u H x 1 4 I I x 1 15 1s 7 m as n 7 9 2a 21 22 x y Knryntynz 47m 3 Trisomy 13 syndrome Trisomy 13 syndrome Palm all Edward an IBM 5301111 Banana 2 3x vsoousmau umnaano m mun unix alum 3mm Mum mu mm mm Imam mum um mun Maulmu Mn mama mm a In lmirl l l mum V quotgin ummm enuuwlm rawIva I u 39 I must mun 3 Patau Syndrome Trisomy 13 noidence 120000 live births Hih ortality rate in 1st year Cip amp palate congenital heart defects polydactyl severe mental retardation 4 CriduChat missing short arm of chr 5 ncidence 1 in 50000 births Possibly normal life expectancy Deleted a region iiil liliif I Catlike cry microencephaly congenital heart disease severe mental retardation may be missing kidneys sensitivity to loud noises low birth weight partial webbing of fingers or toes later protuding teeth normal sized teeth in small head curvature of spine developmental amp language delays possibly selfmutilation amp rocking B Sex Chromosome Disorders Turner Syndrome XO Females in which one Xchromosome or part of it is missing 3i r gtquot s 3 3952 i y a 5 in a v 3quot xei h ff s 3935 igziyzuia 4 s3 2 u 1 9 3 5 c s it I rail O medgengenemsutnh edu Incidence l in IZOD2500 females 90 are spontaneously aborted May not be detected until puberty when secondary sex characteristics amp menstruation do not develop 24 Ovaries do not develop prenatally the girls maintain a very immature appearance Short stature 57 inches average a webbed neck Increased risk of fractures strokes diabetes amp cardiovascular problems Hormone therapy may increase height and induce menstruation occasionally pregnancy accomplished through in vitro fertilization lntelligence is often near average although with severe deficits in spatial ability and directional sense perhaps due to smaller amounts of brain tissue grey amp whitein parietal lobes Reiss 1995 Triple X Svndrome XXX Incidence 1 in 5001200 female Norma sexual development deays in language development lack of motor coordination poor academic performance and immature behavior 3 Klinefelter39s Syndrome XXY males r rnedgen genetocstutanigdu Incidence One in every 500IOOO births absence of development of male secondary sex characteristics facial hair deepening voice increased muscle structure at puberty Underdeveloped testes amp sterile may institute hormone therapy Femalelike fat distribution and potential breast development at puberty Tall and tend to be overweight Cognitive deficits expressive language delays in development poor auditory STM reading difficulties about 20 have mild to moderate retardation selfesteem problems prefer quieter pursuits 4 Jacob s Syndrome XYY lncidence One in 2000 males Aboveaverage height large teeth and sometimes severe acne Overrepresented in prison populations popular defense for a while but not necessarily more aggressive Representation in prisons possibly due to decreased intelligence IV METHODS OF PRENATAL TESTING A Noninvasive techniques 1 Genetic Counseling nformation on a person39s family tree is gathered to ascertain the risk of certain diseases Genetic screening can be carried out on parents to determine their genotype for given disorders eg Cystic Fibrosis Tay Sachs sickle cell anemia 2 Triple Screen Test 15th16th medical weeks up to 18th Maternal blood test measures Alphafeta protein from fetal liver Estriol hCG human Chorionic Gonadotropin inhibin A inoreases detection of Down s estriol high levels of Alphafeta protein may indicate neural tube defect or baby is older than thought or I twins 7585 detection high levels of hCG with low levels of amp AFP indicate elevated risk for Down s Syndrome 60 detection in women lt 35 75 in women gt 35 low levels of all 3 may indicate higher risk for trisomy 18 Edward s syndrome HGH risk of false positive 46 in an online poll of 23 470 parents and some risk of false negatives 32 3 Ultrasound up to delivery High frequency sound waves are beamed into the uterus and their reflection reveals the size shape and position of the fetus a STRUCTURAL measure used to monitor fetal growth estimate gestational age detect multiple pregnancies depict placement of placenta and detect gross structural abnormalities can be done abdominally or transvaginally Figure 1 Fetus with subcutaneous collection of fluid at the back of the neck often seen in Down s Syndrome fetuses amp those with other trisomies Image kindly provided by Dr Eva Pajkrt University of Amsterdam growth abnormalities sometimes indicative of genetic amp chromosomal abnormalities K in weeks l 1544 7 A as v so EekSQ A K x r r in 4 mus Limo SW35 amonihs w 39eis 6 WEeks Birth DOWN39S SYNDROME historically has been claimed that there are no known risks However several studies in 1990s found increase in left handedness in men indicating subtle brain damage 32 increase with two pregnancy scans Swedish study cell damage due to tissue heating Uhlig 1999 cavitation sound waves may cause bubbles to form amp expand reduced fetal weight fetal organ weight birth rate decreased immune system functioning problems with blood platelets have been noticed in humans amp other species exposed to ultrasound mpjeducatevourselforgcn2001 ultrasoundandbraindamaqe19decO1shtml B lnvasive Techniques Usual analysis is for Chromosome abnormalities genetics analysis done only if risk factors for a disease are present 95 of fetuses examined are normal Chorionic Villa Sampling 1013 medical weeks Chorion is the fetal membrane that will form the fetal side of the placenta a tissue sample is removed from chorion by pushing narrow needle in 1520 times Complications 12 risk of inducing miscarriage may interfere with vascularization gt limb deformities Mosaicism a problem for females 2 Amniocentesis 1416th medical weeks Fetal cells are extracted from the amniotic fluid and cultured for chromosomegenetic analysis Com9lications Risk is 335 1300 to 1200 for inducing miscarriage hence benchmark of age 35 Where risk of any chromosome abnormality is 1180 Risk is even higher with early amniocentesis 1114th weeks Rh mothers need Rhogam because of risk of comixing blood of mother amp baby 3 Fetoscopy 1822 medical weeks or after 16 miniature telescopelike instrument w light amp lenses inserted into tiny incision into amniotic sac can detect structural deformities Blood samples taken from junction of umbilical cordplacenta andor tiny bit of fetal or placental tissue removed Complications up to 12 risk of inducing miscarriage up to 47 risk of rupturing membranes necessitating preterm delivery Rh mothers need Rhogam risk of comixing blood of mother amp baby 38 V HEREDITY INFLUENCES on BEHAVIOR A Estimatinq Hereditabilitv 1 Hereditabilitv refers to the extent that individual differences within some population are due to genetics eg hereditability for having 2 eyes is 000 having two eyes is clearly based on genes but no individual differences 2 Concordance Rates amp Correlations Determine hereditability by measuring a trait in individuals with shared genes andor shared environments Biological parents siblings Identical twins raised together or apart Fraternal twins raised together or apart Adoptive parents amp adopted child Biological parents amp adopted child 3 What does the Correlation mean Correlation of r 070 if squared provides amount of variance due to genetics 49 or 49 4 Many personality traits eg lntroExtroversion amp Empathy and Intellectual Traitsskills clearly have an inherited component Average Correlations between IQ scores Bouchard amp McGue 1981 Pederson et al 1985 Segal 2000 Family Pairs Raised Raised Together Apart Identical Twins 86 72 Fraternal Twins 60 52 Biological Siblings 47 24 Biological Parent amp Child 42 22 Half Siblings 31 Adopted Siblings 34 Adoptive Parent amp Adopted Child 19 Unrelated siblings same age same home 26 Hereditability of Temperament Correlations of Angry Emotionality Plomin et al 1988 Raised Together Raised Apart Identical Twins 37 33 Fraternal Twins 17 09 Hereditability of Certain Traits from Minnesota Twin Study Bouchard et al 1990 Height Syst BP Personality Social Attitudes Weight IQ Religiosity 41 5 However environment also impacts almost all inherited skills or traits Gene Environment Interactions Odds of Depression at age 26 Caspi et 3 2003 Hi Number of Stressful Childhood Events B Interaction of Genes amp Environment l Canalization Conrad Waddington the degree to which a trait is constrained by genetics Some traits eg crawling more canalized than others eg playing soccer Think of a river a child39s development seeking its course over terrain Deeply canalized sections will mold the river shallower sections will be molded BY the river Some traits may be heavily canalized early in development eg language development but less so later on eg reading ability 2 Ranqeof Reaction Gottesman 1963 Genes set boundaries amp establish a range of reactions because of different genotypes individuals will respond differently to the same environment 3 Nichepicking ScarrampMcCartney 1983 Genotype contributes propensities toward certain skills and abilities and we then seek activities which are compatible with our genetic endowment Active GenotypeEnvironment interaction 4 Correlations between genetics and environment can also occur a Passively as when parents set up an environment consistent with their and their child39s predispositions eg sociability or b Evocatively as when a child s traits influence the behavior of those around himher eg if a shy child is less engaged
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