Behavioral Psychology Midterm 2 Lecture 1 Genes Cells Behavior Background o DNA makes up chromosomes DNA has a sugar phosphate backbone Its made of 4 bases Adenine Guanine Thymine and Cytosine It s a double helix shape Adenine pairs with Thymine Guanine pairs with Cytosine made Everyone has 46 chromosomes 23 from dad 23 from mom 1 22 are autosomes 23 is sex chromosome DNA codes for instructions to make proteins by two processes 1 Transcription DNA unwinds complementary RNA is 2 Translation RNA is turned into protein using 3 letter codons to string together amino acids proteome proteins encoded by genome genotype set of genetic instructions for example if your mom has brown eyes BB and your dad blue bb you receive Bb That is your genotype phenotype whats actually expressed when you are Bb brown is dominant Brown is the phenotype alleles multiple versions of a gene For example B and b are both alleles B is the brown allele b is the blue allele Homozygous when you have two copies of the same allele BB or bb Heterozygous when you have one of each Bb Dominant gene the one that shows up Bb is brown because B is dominant Recessive genes only expressed when theres no dominant gene only blue when bb Complete dominance only the dominant allele trait is expressed Bb is only brown Incomplete dominance phenotypic expression is only partial o Eg if you have a flower that s R for red and W for white RW marbled red and white Codominance when both traits are expressed o Eg a flower is RW pink o Another example is blood type You can be AA AO BB BO AB or OO mitochondrial DNA mDNA you get all of it from your o mother its used to track evolution of world populations and ancestry sources of genetic diversity 1 Meiosis crossing over 2 Mutations replication errors 3 SNP s when one nucleotide is changed cilantro preference theres a genetic variant near the olfactory receptor genes that determines if you think it tastes good or like soap AA or AG dislike cilantro GG likes cilantro Genetic mutations o Can be good or bad things Ex Sickle cell anemia poor oxygen carrying ability But it helps protect against malaria o Can be specific or widespread Disorders o Tay sachs disease o Huntingtons Progressive nerve deteriotation Early onset around 6 months usually death by 4 Recessive Heterozygotes show protection from tuberculosis Dominant Neurodegenerative Onset midadult life Muscle coordination involuntary moving chorea cognitive Three copies of the 21st chromosome decline o Down Syndrome o Sex linked characteristics Hemophilia Colorblindness More men are colorblind than women because the trait for it is on the X chromosome Women have an extra but men only have one X chromosome inactivation One X in females is silenced to balance protein Epigenetics production o The environment affects whether or not a gene is expressed o Shown by twin studies Monozygotic identical Dizygotic fraternal o A single code can produce multiple differentiations Can explain some diseases One genome may code multiple phenotypes Mechanisms will block or allow protein transcription 1 Histone modification dna may unwrap from the 2 DNA modification transcription to mRNA may be 3 mRNA modification mRNA translation may be histone blocked blocked knock in gene is inserted and is expressed knock out inactivation of gene it is not expressed Practice Question which is not a way epigenetics can alter gene expression o Apoptosis modification Lecture 2 Development of the Brain There are three perspectives on brain dvlpmt o 1 Brain development predicts behavioral develppment o 2 Behavioral development predicts brain development o 3 Hormones genes experience and injury predict both brain and behavioral development and the latter two influence each other Early neural development o Prenatal stages weeks until birth Germ layers Zygote until two weeks embryo until 8 weeks fetus 9 Ectoderm attractoderm or what people find attractive o Brain skin eyes outermost layer Mesoderm meansoderm midd layer o what moves things through your body o muscles and connective tissue circulatory system urogenital system Endoderm innermost layer o Becomes many internal organs Early neural development Ectodermal layer thickens then starts to pinch inward forming the neural groove then pinches off entirely forming the neural tube This turns into the brain and spinal cord Stages of neural development o 1 Neurogenesis cell birth sub ventricular zone neural stem cells line ventricles this is the area where proliferation occurs progenitor cell comes from stem cell can be a neuroblast or glioblast neurotrophic factor acts to support growth and differentiation may help keep adult neurons alive epidermal growth factor EGF turns a stem cell into progenitor basic fibroblast growth factor bFGF turns a progenitor cell into a neuroblast overall stem cell a progenitor neuroblast or glioblast neuroblasts interneuron pyramidal neuron glioblasts astrocytes or oligodendrocytes o 2 Cell migration neurons move from ventricular zone outward move from innermost layer toward skull from layer 6 5 4 3 2 1 o 3 Cell differentiation neuroblasts and glioblasts become specific types of cells essentially complete at birth o 4 Cell maturation dendrite and axon growth continues into adulthood chemical signposts attract or repel advancing neurons axons grow toward target cells filopodia long fingerlike extensions from growth cones lamellipodia flat sheetlike extensions from core of growth cones o 5 Synaptogenesis formation of synapses growth cone approaches muscle fiber makes contact then vesicles accumulate in the axon terminal the interaction with target cells determines which type of neurotransmitters used o 6 Synaptic pruning and cell death extra neurons are produced ahead of time must be eliminated activity dependence neurotrophins chemical factors that influence survival of a cell apoptosis programmed cell death o 7 Myelogenesis formation of myelin occurs in rostral direction spinal cord hindbrain midbrain forebrain some regions myelinate at different rates plasticity ability to change critical period is a limitation on this for example if you patch an eye from birth you wont be able to regain vision in it after a certain period of time before birth until early adulthood long term potentiation LTP o enriched environments increase plasticity stem cells can become other cells neurogenesis production of new neurons in adult brain theres a progressive decline in cortical thickness with age disorders o neural