Genetics• What is heritability, how do we study it (what are twin and adoption studies…what do their results tell us?), and what are the problems with studying it?• Estimate of how much of the variance in characteristic (within a population) is due to a differences in heredity (genes)• Biochemical methods: certain genes more common among people with depression • How much is the gene associated with the condition? How does it produce its effect? What environmental conditions moderate or exacerbate its effect? Canwe undo the effect if it’s undesirable?• Twin studies: Resemblance: MZ > DZ à high heritability Resemblance: MZ = DZ à low heritability. MZ twins share chorion and bloody supply (ex more similar prenatal environment compared to DZ twins).. so could be genetics or could be prenatal enviroment• Adoption Studies: if adopted kids resemble biological parents more than adoptive parents, we assume high heritability. Biological children of low IQ or mentally ill parents tend to have similar problems even if raised by “great” adoptive parents.. could be genes… BUT could be reflection of poor prenatal environment• What are examples of environmental influences on traits with otherwise high heritability?• What is a sex-linked gene? Understand the heritability of sex-linked genes. • The genes on the sex chromosome (X and Y), usually on the X (about 1500 proteins) since there are a lot more genes on it than the Y (about 27 proteins)• If male gets the gene he will display it; female must get it on BOTH of her X chromosomes to display the trait• If female has it on 1 X chromosome and not the other she is a carrier• EX. fragile X syndrome (most common causes of inherited mental retardation), red-green color blindness, Duchenne muscular dystrophy (a progressive degeneration of muscle tissue), hemophilia (a deficiency in one of several blood-clotting factors causes uncontrollable bleeding [apparently Queen Victoria of England was a carrier and spread is through the royal line]• What is a sex-limited gene? What are examples of each (sex-linked and sex-limited)?• Present in both sexes but has an effect only (mostly) in one sex. Genes are “turned on”under influence of sex hormones. Ex. genes for chest hair (men), and breast size (women)• What is the multiplier effect? • Genes predispose you to behaviors and to different treatment by others.• Genes or prenatal influences à increase tendency à environment facilitates• What started out as potentially small effect of genes ends up having a huge behavioralresult… leads to an overestimation of heritability • Terms to know and understand: DNA, RNA, gene, chromosome, transcription, translation, homozygous, heterozygous, dominant, recessive, • DNA: (deoxyribonucleic acid)self replicating, double stranded chemical which is a template for RNA, 4 nucleotides -CGTA• RNA: Copy of one strand of the DNA, template for protein, 4 nucleotides- CGUA, workhorses for the body• Chromosome: contain DNA, we have 46 chromosomes (22 paired [autosomal] chromosomes and 2 sex chromosomes [XX (female) and XY(male)])• Transcription: when a gene is “turned on” or “expressed” it is made into RNA• Translation: when a gene is “turned on” or “expressed” it is made into RNA then into aprotein• Homozygous: (same 2 genes) person with identical set of genes on the 2 chromosomesis homozygous for that gene • Heterozygous: person with unmatched pair of genes of the 2 matched chromosomes isheterozygous for that gene • Dominant: a gene that shows strong effect in heterozygous or homozygous condition (tongue rolling is autosomal dominant and so I Huntington’s disease)• Recessive: a gene that shows strong effect only in homozygous condition (attached earlobes are recessive)• What is evolution? • Change over generations in the frequencies of various genes in a population• Similarities that we see, even between species, suggest a common ancestor. Differences between species allow us to question what pressures may have causes certain animals to develop certain traits• What types of traits move on to the next generation?• Only heritable traits move on to the next generation, acquired traits are not inherited (breaking your pinky finger)• What is natural selection? What is artificial selection? • Natural selection: how species acquires their adaptive characteristics. The process by which inherited traits that confer a selective advantage (increase an animal’s likelihood to survive and reproduce) become more prevalent in a population. Genetic variability occurs due to (1) mixing of DNA (recombination) and (2) random mutations• Artificial selection: choose individuals with desired trait and make them parents• Why did Darwin prefer “decent with modification” to “evolution”?• Evolution = improvement?• For a gene to go on to the next generation, a the carrier must reproduce, BUT what is beneficial for reproduction in one generation, might not be beneficial later (peacock’s tail)• What is epigenetics? Why does this new field of research “blur the line between environment and genetics”?• Changes in phenotype (appearance) or gene expression caused by mechanism other than changes in the underlying DNA sequence• Because you are changing whether the gene will be expressed or not without doing to the DNA itself by only loosening or tightening the wound around the geneDrug Actions and Substance Abuse• In general, all drugs of abuse cause dopamine release in the nucleus accumbens. Okay, not a question, but KNOW THAT!• Stimulants: know some examples of stimulant drugs. What neurotransmitters do they increase? What are some behavioral effects? : Ex. amphetamine, cocaine, Ritalin, ecstasy. Increases dopamine (in nucleus accumbus) and increases serotonin and norepinepherine release. : they increase excitement, activity, alertness, and mood but decrease fatigue– Cocaine: what is its method of action (ie, what does it do at a synapse)? Blocks reuptake of serotonin, dopamine and norepinepherine – What does ritalin do at the synapse? How is it different from cocaine? : same effect as cocaine on dopamine but different time-course and dose (Ritalin increases and decreases slower; take less Ritalin at a time as compared to cocaine)– What does ecstasy do at the synapse? What are the effects of long-term use neurons? What are some psychological/cognitive
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