Human Behavior: Part 2 – Molecular GeneticsEpigenetic movie will be on test (LOOK IT UP)BG (behavioral genetics) illustrates the three main points about phenotypes:1. Shared environment – little influence2. Nonshared - influential3. Heritability – strong genetic componentWhich genetic components are influential for certain phenotypes? Which certain genes are related for causing differences in people? BG cannot give that answer but a different research design can: Molecular GeneticsBasic info about genes:- Approximately 25,000 genes in the human body. When the Human Genome Project began, we were expecting 100,000s of thousands of genes, but no, there are only 25,000.- Genes are stretches of DNA that work together to perform specialized functions.DNA:- A chemical code that allows us to form, develop, and function/live- Stored in the nucleus of every cell except red blood cells- Info encoded into DNA partially determines every observable and unobservable characteristics- People vary because their DNA varies- Every person has their own unique sequence of DNA -Exceptions: Monozygotic twins!- Each person’s arrangement of genes is known as s ‘genotype’. The expression of a genotype is a phenotype, but there are variances due to things like dominant andrecessive genes.Structure of DNA:- Two fibers twisted around each other to form a double helix- Each fiber is referred to as a polynucleotide- Along the backbone of each polynucleotide is a sequence of nucleotides (also called bases)DNA:- Four different types of bases -A -T -C -G- Those letters make up the genetic alphabet and depending on how they arranged will make someone different- Base pairs are held together with chemical bonds- Chemical bonds hold the two strands of DNA together and there is a specific bonding pattern: -A T -G C -T A -C G- The ordering of the base pairs is very important. You will get very different results in terms of phenotypes if the base pairs vary in ordering.- Differences in genotypes will cause significant differences in phenotypes.- Humans share about 99.9% of their DNA- About 0.1% of DNA is responsible for many of the changes among the human population -Distinguishing DNA: We can use that phrase when we talk about any 2 people.- Base pairs working together are called genes- In reality, genes are made up of 1,000 or more base pairsWhat do genes do? -They code for the production of protein -Proteins are essential to life: 1) Structural Proteins -Hair, nails, tendons, ECT. 2) Functional Protein -Coordinate actions and activities of the body2/18/13Molecule Genetics:Genes and the environment- Nature and nurture- Combined to create different behaviors and different personality traits -It helps answer the question as to why people with the same genetic material turn out differenty?- Because of the combination of nurture and nature, also referred to as gene-environment interplay.Two main types of gene-environment interplay1. Gene X environment interactions (GxE)2. Gene X environment correlations (rGE) GxE- Genetic effects are only visible or highly visible in certain environment -Conversely, environmental effects are most potent given the presences of certain phenotypes- Two people in the same environment may interpret it and react to it differently because of their unique genotypes.- Can explain why children in the same family turn out differently. Every sperm that fertilizes an egg carries a different genetic material, except for monozygotic twins.- Can also explain why rehabilitation effort works for some people but not for others because of their genotypes interacting with that program.- Remember Caspi et al.’s article: -They found that the certain gene only had an effect in certain environment -Classic example of GxE- A growing body of empirical evidence has revealed the importance of GxEs in theetiology of crime and delinquency.rGE:- We often see that an environment is related to a person’s behaviors or their personality traits- We think that the environment caused this association (the environment was there before the child was born) -Ex: An intelligent child who is always reading and engaging in stimulating cognitive stimulation -The SSSM would say that if you place a child in a room of books or have your fetus listen to Mozart; it would boost your child’s IQ (which is bullshit)- BUT, IQ and cognitive ability are heritable traits, and then just having the good environment for that isn’t enough. - Intelligent parents are more likely to have intelligent children -Assortative mating increases this possibility- Intelligent parents also more likely to have books and other cognitive stimuli in the home -The environment reflects their genetic propensities/abilities- Other examples are plentiful: -Musical ability, mechanical abilities, athletic abilities, ECT.- Refers to the close association between the genes and the environmentThere are 3 types of rGE:1. Passive: - Things like IQ and sports gene. Children receive 2 elements from parents, genetic and environment. It’s received passably. The child has no influence or say of the genetics that they get OR the environment that they grow up in. The environment is largely a reflection of their parents’ genetic propensities.2. Active:- Individuals play an active role in seeking out environment that are compatible with their genetic tendencies.- Engage in ‘niche-picking’: you go to areas or activities that you like where you can find other people who also like that stuff.-3. Evocative:- People elicit certain responses from their environment based, in large, part on their genotype. Two people will elicit two different responses from the same environment. For example, if someone gets mad easily, you would tweak your behavior to not make them mad.- If someone is a negative person, you won’t call them as much.2/20/13Molecular GeneticsWhich genes may relate to ASB?- Genes responsible for the production transportation, and breaking down of neurotransmitters are the most promisingNeurotransmitters:- Chemical messengers that allow for communication between neurons- Sends electric
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