EXAM2PSYCH - Section 5.1 Chromosomes Strands of hereditary...

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Section 5.1 Chromosomes Strands of hereditary material Everyone has 23 pairs Gene Control the chemical reactions that direct development Ex. Controlling height or hair color Made out of DNA DNA control the production of RNA which controls the production of protein among other things Dominant – a single copy of the gene is sufficient to produce its effect Recessive – its effects appear only if the dominant gene is absent Sex chromosomes Determine whether an individual develops as a male or as a female Female have two X chromosomes Male have one X and one Y chromosomes Mothers contribute the X chromosomes Father contributes the Y chromosomes Sex-linked (X-linked) gene genes located on the X chromosomes X-linked recessive gene shows its effect more in men than in women Ex. If there is a color blindness gene on and X chromosomes then men are likely to get it because they don’t have another X chromosome to pick from. However female have two X chromosomes so they have a 50% of getting the color blindness Sex-limited gene – occurs equally in both sexes but exerts its effects mainly or entirely in one or the other. Ex. Both men and women have the gene for facial hair but men’s hormones activate those gene. And both men and women have the genes for breast development but women’s hormones activate those gene. All behavior depends on both heredity and environment Heritability an estimate of the variance within a population that is due to heredity 1 indicate that heredity controls all the variance 0 indicate that it control none of it
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Some times heritability is misleading because we cannot separate the effects of heredity and the environment Multiplier effect A small initial advantage in some behavior possibly genetic in origin alters the environment and magnifies that advantage Ex. You and the gene that made you tall then you start playing basketball when you were a kid. As you get older you join a team which with coaching you become even better. What start as a small genetic advantage in height develops into a huge advantage in basketball skills Monozygotic twins (identical twins) – twins that develop from a single fertilized egg and therefore have identical genes Dizygotic twins (fraternal twins) – twins that develop from two fertilized eggs and share only half their genes If dizygotic twins resemble each other almost as much as monozygotic twins then we conclude that the heritability of that trait is low If monozygotic twins resemble each other much more strongly then the heritability is high Research have found at least moderate heritability for almost every behavior they have examined Genes control maturation of brain structures, production of neurotransmitters, and production of neurotransmitters receptors Genes also influence behaviors by altering body anatomy Ex. Consider you have that gene that makes you unusually good-looking. Because many people smile at you and try to become your friend Increase your
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EXAM2PSYCH - Section 5.1 Chromosomes Strands of hereditary...

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