SI Worksheet 3.4: Applied Behavioral Genetics PDF

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BioPsych
Dr. D'Anna-Hernandez...

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Biopsychology Worksheet 3.4 – Applied Behavioral Genetics A bit more on Heritability: 1. Can we ask “how much” of our behavior is due to genes and “how much” is due to environment? Why or why not? -euqually important -can’t quantify how much or % is due to genes and how much is due to envinroment -but we can say how much of differences or variation in behavior or another trait among people in a population are due to differences/variation in genes

2. Decide whether or not we can say the following, and what each of the following mean: a. Personality is 80% heritable. 80% of the differences/varation that we see in personality are due to differences in genes in this population (in califonria, in CSUSM) b. Jeremy found out that attractiveness is 75% heritable, so now he says that he got 75% of his good looks from his genes and the rest from his environment. -can’t apply to an individual – it’s a population statistic -but Jeremy can say : “75% of differences in attractiveness can be attributed/are due to differences/vvaraition in genes in the population” c. Lisa inherited her motivation. -she’s talking about heredity which is correct because it applies to an individual

Cognitive Ability 3. How can we explain differences in IQ between groups? What about within groups? (see plant thing)

1. Between group differences: the only difference between the 2 groups is soil/totally environmental because the two groups have the same genes (seeds)

(e.g., take clones of CSUSM students and put them in sub-saharan Africa. The students are identical genetically, so the differences we see are due to differences in environment). 2. within group differences: differences within the same group/environment will be due to differences in genes because this one group has the same environment. We do heritability within a single population. 4. Is cognitive ability totally dependent on genes? Provide examples of research to support your answer. No. 1. Maze bright/dull: differences in genes interacted with differences in the environment differently. In restricted environment, bright and dull did poorly, but in enriched environment, their maze-running/cognitive abilities improved significantly 2. Twin Studies: raising MZ twin together and apart. Together = 90%correlation, but when raised apart they have a 75% correlation. The environment affected how alike or different they were in cognitive ability traits 3. Genie – parents locked her in a room: wasn’t able to function/learn language etc due to missing a critical period of developmental enrichment

Schizophrenia A. Name three symptoms 1. Hallucinations (positive trait) 2. Delusions (positive trait) – grandeur (think you’re god), paranoia (the gov is after you) 3. Catatonia (negative trait) stop moving/stiffen Disorganized speech, flat affect (no emotion), avolition (no motivation) B. At around what age does this disorder usually strike? Late teens early twenties. Depending on the liability threshold score, onset can be triggered sooner or later depending on environmental trigger. For example, if I have a lot more “bad” alleles past the threshold, I will likely develop schizophrenia sooner due to less of an environmental trigger. If I barely meet the threshold, I might develop it at a later age because a greater environemetnal trigger is needed. C. Twin Studies: Explain the findings of twin studies on schizophrenia and what those findings mean about the cause of the disorder. In MZ twins they found a 41% to 65% concordance rate for schizophrenia. In DZ they found a 0% to 28% concordance rate. Because MZ share 100% of the same DNA, and DZ only share 50%, the higher concordance rate among MZ tells us that there is a strong genetic component to this seen through high heritability. The DZ are more different in this trait due to more differences in genes.

D. Adoption Studies: According to the Adoptees Family Method, does growing up in a family with a schizophrenic affect an adoptee’s risk of being affected? No because I must have the genetic predisposition. I must meet the liability threshold to even be eligible of developing schizophrenia. To get schizophrenia, we need an environmental trigger, but if you do not have the genes, then there is nothing to be triggered. E. True/False _F___ Schizophrenia runs in families but only a certain subtype is inherited. Different alleles account for different schizophrenic traits/symptoms. For example, if your dad has paranoid schizophrenia, you might get that too, or you could become a catatonic schizophrenic from inheriting other “bad” alleles that account for these schizophrenic symptoms. ___F_ The less severe form of schizophrenia is more heritable. The more severe symptoms of schizophrenia are attributed to more “bad” or affected alleles that contribute to schizophrenic symptoms. The more severe forms of schizophrenia are more heritable because there is a stronger genetic component, and you need less of an environmental trigger to develop with increased liability threshold score. _T___ Type II, or Hebephrenia Schizophrenia, is characterized by passive symptoms, like withdrawal, and an overall poor diagnosis. Type II is characterized by negative symptoms, and Type I is characterized by positive symptoms. __T__ Jerky eye tracking is an endophenotype of severe schizophrenia. Endophenotype – a characteristic associated with an illness, but not a direct symptom. So if you have schizophrenia, you’’re probably more likely to have this phenotype/trait, but if you have the trait you’re not more likely to have schizophrenia, and it doesn’t mean you have schizophrenia. ___F_ Schizophrenia is caused by one gene of large effect this is a quantitative trait, meaning you need many “bad” or affected alleles to get the trait ___F_ Drugs used to treat schizophrenia usually are dopamine and serotonin antagonists. Only dopamine, not serotonin...