4Study Questions Exam 1 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 Heritability Estimate of how much of the variance in a characteristic within a population is due to differences in heredity genes All found to have a heritable component except religious affiliation Genes brain behavior Adoption adopted children showing similar behavior to parents environmental LOW heritability not like adoptive parents HIGH heritability Twin studies compare monozygotic 100 same DNA and dizygotic twins same amount shared DNA as normal siblings o If identical twins are more likely to both show a trait it has HIGH heritability o If Fraternal twins w different DNA both show trait LOW heritability could also be prenatal environment Problems o Twin Studies MZ twins share chorion and blood supply ie more similar prenatal environment compared to DZ twins so could be genetics OR could be prenatal environment o Adoption Studies Biological children of low IQ or mentally ill parents tend to have similar problems even if raised by great adoptive parents Could be genetics BUT could be reflection of poor prenatal environment o Genes predispose you to behaviors and to different treatment by others Multiplier Effect What are examples of environmental influences on traits with otherwise high heritability Elevated plus maze some genetic strains in mice tend to stay in walled arms others venture out onto open arms BUT sometimes a strain that is unadventurous in one lab is more adventurous in another Phenylketonuria PKU mental retardation due to genetic inability to metabolize phenylalenine an amino acid Difficult diet avoid eggs meat dairy grains aspartame which is 50 phenylalenine What is a sex linked gene Understand the heritability of sex linked genes What is a sex limited gene What are examples of each sex linked and sex limited Sex linked genes the X bc it has more genes than Y The genes on the sex chromosomes X and Y Usually on o Female could be a carrier of R G colorblindness on one X chromosome but not on both so don t show o Men only have one X so if it is on there the gene shows o Ex Fragile X Syndrome most common mostly mental impairments but many more Red green color blindness Duchenne muscular dystrophy Hemophilia blood clotting disorder Sex limited genes on the sex chromosomes Not on sex chromosome on the autosomal but expressed o Present in both sexes but has an effect only mostly in one sex o Everyone has the same genes but are only turned on by a critical level of gender specific hormones o Turned on by high levels of testosterone estrogen or progesterone o Ex Chest hair Breast Tissue Growth What is the multiplier effect environment facilitates it Genes or prenatal influences increases tendency for a trait to show and the What started out as potentially small effect of genes ends up having a huge behavioral result leading to an overestimation of heritability Child had a certain combo of genes then exposed to environment which responded to that gene therefore enhancing these traits MULTIPLIER EFFECT Examples temper tantrums attractiveness athletics Terms to know and understand DNA Double stranded chemical A gene is a portion of a DNA strand self replicating template for RNA RNA Single stranded chemical Code Template for protein Copy of one strand of DNA Gene sequences of DNA the code for proteins contain information on hereditary the process of forming a polypeptide chain of Amino Acids from characteristics Chromosome contain DNA 22 paired autosomal chromosomes two sex chromosomes XX Female XY Male Transcription the process of creating a complimentary RNA copy of a sequence of DNA Translation mRNA messenger RNA Homozygous Person with identical set of genes on the 2 chromosomes blue blue Heterozygous Person with unmatched pair of genes on the 2 matched chromosomes brown blue Dominant A gene that shows strong effect in heterozygous or homozygous condition brown Recessive A gene that shows strong effect only in homozygous condition blue What is evolution What types of traits move on to the next generation What is natural selection What is artificial selection Why did Darwin prefer decent with modification to evolution Evolution population Change over generations in the frequencies of various genes in a Only heritable traits move on to the next generation acquired traits are not Natural selection inherited if certain individuals are more successful live to reproductive age their genes will become more prevalent the key mechanism of evolution As opposed to artificial selection choose individuals w desired trait make them parents Darwin preferred modification bc for a gene to go on to next generation carrier must reproduce BUT what is beneficial for reproduction in one generation might not be beneficial later peacock s tail peppered moth Ex broken pinky wont transfer to offspring What is epigenetics Why does this new field of research blur the line between environment and genetics Epigenetics by mechanisms other than changes in the underlying DNA sequence changes in phenotype appearance or gene expression caused o DNA is wrapped around a histone core Things acetyl groups methyl groups etc can get into the structure and loosen or tighten the wound up DNA This will make a gene more or less likely to be expressed AND these changes are heritable SO you can alter the probability that a gene will be expressed without actually altering the DNA itself These changes may remain through cell divisions for the remainder of the cell s life and may also last for multiple generations However there is no change in the underlying DNA sequence of the organism instead non genetic factors cause the organism s genes to behave or express themselves differently Chemicals can loosen or tighten coil can affect how likely it is to be expressed Life experiences can trigger these chemical and then can be passed on to your offspring like malnutrition or extreme stress It blurs the line because originally we thought that environmental factors were determined solely based on what happens after conception such as prenatal environment parents class etc and genetic factors were determined only by the combination of your parents DNA and it was believed that these two could not mix However epigenetics shows us that the environment can actually activate or deactivate certain genes your environment can affect your genetics An
View Full Document
Unlocking...