GENES- Introduction to Geneticso There are approximately 25,000 genes in the human bodyo Genes are stretches of DNA that work together to perform specialized functionso To better understand gene, we need to discuss DNAo DNA is a chemical code that allows us to form, develop and liveo DNA is stored in the nucleus of every cell except for red blood cellso Information coded to DNA determines virtually every observable and many unobservable characteristics (second half debated by criminologists)o People vary because their DNA varieso Every person has their own sequence of DNA (aside from MZ twins)o Each person’s arrangement of genes is referred to as a genotypeo The structure of DNA1. Two fibers twisted around each other to for a double helix2. Each fiber is referred to as polynucleotide (poly means “a lot”)3. Along the backbone of each is a sequence of nucleotideso There are four types of bases:1. Adenine2. Thymine3. Cytosine4. Guanineo How are the two polynucleotides held together? Through bonds between the bases. Specifically A pairs with T and G pairs with C. These bonds hold the two strands of DNA togethero The ordering of pairs(base) is very importanto Very small divergences can alter drastically what we are studyingo Humans and Chimps share over 96% of their DNA. We often fail to realize how similar we areo Humans share about 99.9% of their DNA.o .01 of DNA is responsible for many of the changes among the human population. (You and I share between 90-99%)o At various segments along DNA, contiguous base pairs work togethero These base pairs, working together, are called genes.o In reality, genes are made up of 1,000 or more base pairso What do genes do?1. They code for production of proteins2. Proteins are essential to life- Structural proteins= hair, tendons, fingernails- Functional proteins= coordinate actions and all activities of the body (we will focus on functional proteins because partially responsible for brain activity)o Genes are configured on threadlike structures called chromosomeso The human body contains 23 pairs of chromosomes; one pair is inherited maternally andone pair is inherited paternallyo Females have two X chromosomes and males have an X and Y chromosomeso Every person has 2 copies of most genes (one from mom and one from dad)o The two copies make up the entire geneo Each copy is referred to as an allele. 2 allele=1 geneo For most genes, only one allele exists in the populationo But for a small fraction of genes, there are at least two alleles that are in existenceo These genes are referred to as polymorphisms- Polymorphisms are genes that can vary- Why? Example with heighto How do genes vary?1. Single nucleotides polymorphismsACGAGGACCAGTTAACGAGCACCAGTTA2. Short tandem repeatsTAGGAATTATTATTATTATTATAGGAATTATTATTATTATTA3. Variable # of tandem repeats (VNTRs)Same as STRs except more nucleotides are repeated (hundreds)Different polymorphisms can affect the functioning of the human bodyGenotype- How can genes affect phenotypeso One gene, one disordero Polygenic and pleiotropic effects- OGODo Single genesingle phenotypeo This does not mean if you have these alleles you will be a criminalo Not genetic determinism- Polygenic EffectsMany Geneso Not deterministic, but probabilisticSingle phenotypeo Gene will only count for a small (effects) percentage= not deterministic- Pleiotropic effectOne geneo Research suggest that crime is the effect of plietropic effectso Neglecting role of environment for all 3- Genes and the environmento Genes and the environment often combine to create different behaviors and different personality traitso Not nature vs nurture but nature and nurtureo Referred to as gene environment interplayo Epigenetics is a type ofo Two are types of gene environment interplay:1. Gene X environment interactions (GxE)2. Gene X Environment Correlations (rGE)- Gene X Environment interactionso Genetic effects are only visible in certain environmentso Two people in the same environement may interpret it and react to it differently because of their unique genotypes Environment working with genes to make trait active Beavers father vs father in law- cholesterol exam- GXEso GXEs can explain why children in the same family turn out differently We filter and experience things differentlyo GXEs can explain why rehabilitation efforts work for some people but not for otherso GXEs can explain why the environment does not have the same effect on all people Is it Michal Jordans genes or his environment?o Rememeber Caspi et al’s article They found that the certain gene only had an effect in certain environments- This Is a classic example of a GXE- A growing body of empirical evidence has revealed the importance of GXEs in the etiology of crime and delinquency- Gene X Environment correlationso We often see that an environment is related to a persons behaviors or their personality traitso We think that the environment caused their association- RGEso RGEs refer to the close association between genes and the environmento There are 3 types of RGEs Passive RGEsMultiple phenotypes Active RGEs Evocative RGEs- Passive RGEso Children receive two elements from their parents: genes and the environmento Passively receive both from their parentso The environment is largely a reflection of their parents genetic propensities Example- Previous exam w/IQ Violent parents= cold abusive drawn detached Passively inherit genes and environment- Evocative RGEso People elicit certain responses from their environment, based in large part on their genotypeo Two people will elicit two responses from the same environment Example: bad temper, attractiveness Spanking  aggression- Active RGEso Individuals play an active role in seeking out environments that are compatible with their genetic tendencies Engage in “nuche-picking” Example: thrill seeking and skydiving; delinquent peers People select their environment (friends) can be based on genes which drive thetraits- Which genes may relate to antisocial behavior?o Genes responsible for the production, transportation and breaking down of neurotransmitters are the most promisingo What are the neurotransmitters? Chemical messengers that allow for communication between neurons We don’t know a lot of the specific genes- Neurotransmitterso Billions of neurons in the human braino Thousands of connections for each neurono Space between neurons Synaptic cleft or synapse