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Chapter 3

Psychological Science Chapter 3

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Dan Dolderman

CH 3 NotesHuman genome may consist of just over 20000 genesHumans complexity may be due not simply to our possessing a large number of genes but to subtleties in how those genes are expressed and regulatedUnderstanding how genes work should enable medical researchers down the line to cure various ailments by altering gene functionsThe first clues to the mechanism responsible for heredity were discovered by the monk Gregor Mendel around 1866 o Selective breeding strictly controlled which plants bred with which other plants o 31 ratioDominant gene a gene that is expressed in the offspring whenever it us presentRecessive gene a gene that is expressed only when it is matched with a similar gene from the other parentMendels experiments with crossbreeding pea blossoms resulted in purple flowers by 75 of the time and which flowers 25 of the timeGenotype organisms genetic constitution the genetic makeup determined at the moment of conceptionPhenotype organisms observable physical characteristics which result from genetic and environmental influencesPolygenic effect a spectrum of physical characteristics ex skin colorReproductive cells divide to produce gametes egg and sperm cells each of which contains half of every chromosome pairFertilization results in the production of a zygoteCell division the cells duplicate and divide into 2 new cells with an identical chromosome structureMutations can range from severe to mild or benignIndustrial melanism a phenomenon in which areas of the world with heavy soot or smog tend to change the colors of organisms ex mothsbutterfliesSicklecell gene is recessive only those who receive it from both parents being carriers will express the diseaseBehavioural genetics the study of how genes and the environment interact to influence psychological activityTwin studies compare similarities and differences to determine the genetic basis of specific traitsMonozygotic twins identical twins come from one zygoteDizygotic twins fraternal come from two fertilized eggs separately but growing in the same wombAdoption studies compare the similarities between biological relatives and adoptive relativesHeredity the transmission of characteristics from parents to offspring through genesHeritability a statistical estimate of the variation caused by differences in heredityVariation the differences among a group of people for one particular traitLow levels of MAO monoamine oxidase have been implicated with aggressive behavioursBoys with the lowMAO gene appeared to be especially susceptible to early childhood maltreatment and were much more likely to be violentChanging ones genes expression leads to the expression of another series of genesNeurons basic units of the nervous system specialize in communication o Operate through electrical impulses o Communicate through chemical signals
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