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PSYC 100
Jaime Palmer

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CHAP4 Genetic influence - Physical development, nervous system -> genetic blueprint from our parents. - Biological characteristics and environmental forces determine our behaviour. Chromosomes and genes - How genetic transmission passed down? Semi-correct answer provided from Hippocrates. - Gregor Mendel, a monk, marked the beginning of modern genetic theory. - Produce visible characteristics of possible transmission to another generation. - Genotype: specific genetic makeup of an individual. Sometimes used, not used, varied. - Phenotype: observable characteristics. Can be affected by other genes & environment. - 2 cells (eggs & sperm) carry the material of heredity – chromosomes, is the beginning of a new individual: zygote. - Chromosomes: tightly coiled molecule of DNA partly covered by protein. - DNA: (deoxyribonucleic acid) carried the heredity blueprint in unit called genes. - Genes: carries info about your characteristics, potentials and limitations. - Every cell has 46 chromosomes – except the sex cell (has 23) because egg & sperm = 46. - Each cell in your body contains the genetic code for your entire body. - Alleles: alternative form of a gene that produces different characteristics. - Genes affect our body’s development & functioning through one general mechanism: genes code for the production of proteins (est. 70 000 different types) - Proteins: control the structure of individual cells and all the chemical reactors necessary to sustain the cell. - ~1/2 genes target brain structure & function. - Each gene carries the code for a specific protein. - A gene can, at different metabolic and environmental factors, activate and deactivate levels of specific protein. - As the protein levels change, there is a corresponding change in function of that neuron & neural circuits. Dominant, recessive & polygenic effects p.111 - Some genes are dominant and some are recessive. - Dominant: particular characteristic will be displayed. - Recessive: characteristic will not show up (unless both genes are recessive) - Both D&R can be passed on but R usually remains hidden. - Polygenic transmission: picture that would occur if all characteristics were determined by one pair of genes. Also magnifies the number of possible variations in a trait that can occur. - Human genes are 99.9% identical: union of sperm & egg can result in about to trillion potential genotypes. Mapping the genetic code - Genetic structure has been mapped by using methods to disassemble the genes on each chromosome & study the specific sequence of substance that occur in each gene: A, T, C & G (Adenine, Thymine, Cytosine & Guanine) = 3.1 billion. - Humans have fewer genes than expected: 25 000 not 100 000. - Apx. 200 human genes may have arisen from genes that bacteria inserted into our early ancestors. Genetic Engineering: The Edge of creation p.112 - Recombinant DNA procedures: use certain enzymes to cut the long thread like molecules of genetic DNA into pieces, combine them with another organism and insert them into a host organism. - Recent gene-modification research by psychologist has focused on processes such as learning, memory, emotion & motivation. - Gene knockout: particular function of a gene is eliminated. Help determine the importance of particular transmitter substance in relation to the behaviours of interest – doesn’t mean a singular gene is wholly responsible. - Very little behaviour is controlled by a singular gene. IN REVIEW p.112 - DNA carries 23 pairs of chromosomes in genes. - Some genes are dominant/some are recessive. - Genes influence development, structure & function. - Genetic engineering allows scientists to duplicate (alter) genetic material or to repair dysfunctional genes. Behaviour genetics techniques p.113 - Probability of sharing any particular gene with one of your parent is 50%, grandparents 25%. - Heritability coefficient: Extent to which variation in a particular characteristic within a group can be attributed to genetic factors. - Heredity: passage of characteristics from parents to offspring by way of genes. - Heritability: how much of the variation in a characteristic within a population can be attributed to genetic differences. Differences/variance in trait across individuals. - Concordance/co-occurrence: possible genetic contribution. - Adoption study: Adapted earlier & compared on some characteristic both with the biological parents & with adoptive parents. - Twin studies: More powerful techniques used in behavioural genetics. - Monozygotic: Identical twins develop from the some fertilized egg, genetically identical. 1/250 births. - Dizygotic: fraternal twins develop from two fertilized eggs, share 50% of genetic endowment like other siblings. 1/125 births. - Many psychological characteristics, including IQ, personality, psyc. Disorders have a notable genetic contribution. - Genetic & environmental factors almost always interact with each other to influence behaviour. IN REVIEW p.116 - Genetic & environmental factors in psychological traits & behaviours. - Major studies are adoption & twin studies. - Most useful research is the study of identical & fraternal twins from two different environments. - Behaviour genetics techniques allow a heritability coefficient to be determined for different characteristics. - Heritability coefficient indicated the extent to which variation in a particular characteristic can be attributed to genetic factors. Genetic influence on behaviour p.117 - Individual characteristics as individuals = experience & environment = acting on our genetic makeup. - All behaviour = reflect genes & environment. - Study of genes – environment interaction from studies of intelligence & personality. Heredity, environment & intelligence - The more genes people have in common the more similar they are in IQ. Biological reaction range, the environment, personality & intelligence p.118 - Reaction range: range of possibilities that the genetic code allows. - 2 factors influence our potential our genetic inherence & the opportunities our environment provides for acquiring intellectual skills. This also depends on our own interest; motivation & personal characteristics --> affect how much we apply. Behaviour genetics & personality - Personality could be traced. Difference in brain development or function. - Personality trait theory: Five Factor Model believe that individual differences in personality can be accounted for by variation along 5 personality dimensions. 1. Extraversion – Introversion (sociable, outgoing, adventuresome) 2. Agreeableness (cooperative, helpful, good-natured) 3. Conscientiousness (responsible, goal-directed, dependable) 4. Neuroticism (worrying, anxious, emotionally unstable) 5. Openness to experience (imaginative, artistically sensitive) - Generic factors account for a significant amount of personality difference. 1. Variation attributable to genetic factors. 2. Variation due to a shared family environment among those reared together. 3. Variation attributable to other factors (ex: individual experiences) - Minnesota Twin Study – 400 pairs of twins: environment accounted for little to no variation. - Genes control development & function of physical characteristics all so balance. IN REVIEW p.123 - (+) correlation between similarity genetics & IQ. (&important envoronemt role) - Genes give us a reaction rage yet our IQ depends on environment factors. - Identical twins > fraternal twins. - Genetic fact
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