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Psychology Review

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Dan Dolderman

Psychology Review: CHAPTER 3(Biological Foundations) Genetic Basis of Psychology: - Biology + Environment = mutual relationship that both affect each other - Genetics: hair height turning genes on/off - Human Genome Project (Humans only have 30,000 genes!) - There is a genome for making the entire org in almost every cell - Genome = master blue print with detailed instructions - Genome provides the OPTION, enviro determines WHICH option is taken - Each cell has chromosomes: structures made of genes - 23 pairs of chromosomes ( from each parent) - Genes are components of DNA: sequence of molecules in each strand specifies exact instruction to make a distinct proteins (basic chem that make up cell structure + direct activities) - Enviro says when to which + when to make - Some genes sensitive to temp will be expressed - Gene: part of DNA that carries out a specific task/ determines characteristics - Cells become specialized based on which gene expressed - Determines bodys make up/ development of psychological activity Hereditary = Passing Along Genes thru Repro - Mendel, first clues to heredity by studying plants - Selective breeding - Conclusion: plants had genes that existed in diff versions (purple/white) - Offsprings features: - Dominant gene: gene expressed in offspring whenever present - Recessive: gene expressed only if matched with similar gene from other parent GENOTYPE vs PHENOTYPE: - Dominant + recessive genes - Genotype: orgs genetic constitution, makeup determined at moment of conception - Phenotype: orgs obv, physical characteristics from genetic + enviro influences - Mendels experiments (pheno=purple color=dominant) Ex) Phenylketonuria (PKU milk): cant be broken down by infants, can make brain damage, so modified by low PKU diet POLYGENIC EFFECTS: range of variability for a certain characteristic (height/intell) in a pop - Influenced by genes + enviro - Skin color in not inherited like flower color in Mendels research - Variety of sin colors (P) is not the end product of a single dominant/recessive gene pairing (G), but effect of multiple genes SEXUAL REPRO = VARIATION - Specific combination of genes, determined part by random cell division before reproduction - Sex chromo: (X,Y because of shapes) 1) Reproductive cells divide = gametes (egg + sperm cells with half of every chromo pair) 2) Fertilization = combine gametes = zygote (fertilized cell with 23 pairs, from each parent) - Zygote grows through cell division: chromosome duplicated and cells divide into 2 new cells with identical chromo structure - Error = mutations mostly benign, and can be adaptive OR maladaptive Ex adaptive) Industrial Melanism: moths adapted darker color in areas with heavy soot/smog to camouflage from predators Ex maladaptive) Sickle Cell Disease: genetic disorder that alters bloodstreams processing of oxygen = BAD, but increases resistance to malaria = GOOD - Recessive gene in African decent - Last in gene pool because dont interfere with everyones health 3) Unique genotype created at conception = genetic variation in humans Genes Affect Behavior - Abilities + psych traits influenced by interaction of your genes + enviro you were raised in/exposed to - Behavioral genetics: study of how genes + enviro interact to influence psych activity - Science indicates that genes lay the groundwork for many human traits - Psych scientists study the ways genes are expressed in enviro (characteristics influenced by nature + nurture + combination) BEHAVIOURAL GENETICS (BG) METHODS: - Differences in siblings expected because they dont share identical genes OR life experiences - SO, BG use 2 methods to asses degree to which traits are inherited: 1) TWIN STUDIES: Monozygotic Twins: twin siblings who result from 1 zygote splitting in 2 and therefore share the same genes (identical twins) - Research says their DNA might not be identical bc of subtle diff in how mothers + fathers genes combined - More similar than Di Dizygotic Twins: twin siblings who result from 2 separately fertilized eggs (fraternal twins) - Differ in G and P 2) ADOPTIVE STUDIES: - Compare similarities between bio relative and adoptive relatives - Nonbio adopted siblings share same home but have diff genes, SO similarities would have to do more with enviro than genes - 1 way, compare mono twins who have been raised together vs. raised apart - Identical twins, raised together or not, more likely to be similar - Twins raised a part may be more similar than twins raised together Ex) Jim Twins (married, divorced, gave birthday identical way) OR Oskar Stohr + Jack Yufe (raised in diff cultures, behaved the same) - Twins + relatives share similarities beyond coincidental attributes + behavior quirks Ex) shyness tends to run in families bc of strong genetic components UNDERSTANDING HERITABILITY: - Heredity: transmission of characteristics from parents to offspring by means of genes VS HERITABILITY: statistical estimate of the variation, caused by differences in heredity, in a trait within a pop - Refers to POPS NOT INDIVIDUALS - Depends on the VARIATION - Once we know the typical amount of variation in a pop, we can see if people who are related show less variation Ex) height has .60 heritability = 60% of higher variation for people in a pop is genetic - Heredity value of having 2 legs = almost 0 Estimated of heritability are concerned only with the extent that ppl differ in terms of their genetic makeup in a group SOCIAL + ENVIRO INFLUENCE GENETIC EXPRESSION Ex) New Zealand Study is a good example of how nature + nurture together affect behavior, in this case violent behavior Caspis Study: Hypothesis: enzyme monoamine oxidase (MAO) may be important in finding susceptibility to effects of maltreatment, bc low levels of MAO have been implicated in aggressive behavior - studied 1000 people from birth to childhood - measured which were mistreated by parents (nurture) - measured the presence of MAO gene, one leads to higher levels and other leads to lower levels (nature) - measure the tendency toward criminal behavior - RESULT = gene for low MAO more likely to be convicted of violent crimes if maltreated as children Scarrs Study: early environments influence young children, but genes also influence their experiences Ex) Children exposed to same environment react to it in different ways: Teasing = withdraw, shrug it off, fighting - Differences in how they react to event evoke diff responses from others Ex) Well mannered cuddly child evokes more nurturing parents than a bad child - Genes predispose people to certain behaviors, which elicit diff responses, and their interaction shape their phenotype - Genes + social contexts interact, SO, separating their independent effect = HARD GENETIC EXPRESSION CAN BE MODIFIED - Manipulate/insert genes to enhance/ reduce a particular genes expression - Then compare GMO with unmodified ones to test theories about the affected Mice dont have a specific social gene, genes functions but changing one Ex) K.O mice, where genes have been K.Od: if gene is important it will interfere with genes expression = functioning expression of a series - Changing a single gene can dramatically change behavior of other genes = - Gene manipulations made: anxious, hyperactive, forgetful, etc mice complex behavior Ex) gene from highly social prairie vole put into antisocial mice = exhibited behavior more typical of prairies than mice
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