Psyc 4640 1st Edition Lecture 2 Current Lecture Genes strands of chromosomes Chromosomes made of DNA DNA 4 nucleotides CGAT Chromosomes come in prs 23 prs 46 in humans If an indiv has the same gene on a pr of chromosomes associated condition is homozygous Diff gene on each heterozygous Genes are dominant or recessive Dominant overpowers in homo and hetero conditions Recessive only matters in homo Human chromosome has been mapped We have 30 000 genes Non gene stuff on chr is not junk as once thought All but one pair are autosomal they are the same Sex linked chromosomes may differ within their pair and determine the sex Sex linked characteristic is usually on X chromosome o Ex Color blindness on X Recessive much more common in males Sex limited genes can be on any chromosome and either sex but only activated in a certain sex Mutations Combinations and recombinations of X Y chromosomes Usually recessive and located on a single gene o If you have a gene for Huntington s you will get it Some conditions resulting from mutations are much more modifiable Rarely mutations are good and leave an advantage for an organism Survival of fittest Over long periods of time mutation may be incorporated into DNA Evolution Have found changes w i a generation Non gene junk are on off switches Environmental stressors diet etc can trigger them Nature vs Nurture Determined by heritability factor estimate of variants of something that is due to genetics It s a correlation coefficient 0 1 Indirect effect of genetics multiplier effect enviro may exasperate genetic effects o Ex Tall a parents think you might be good at basketball a most basketball players are tall Epigenetics study of cellular and physical traits that can be inherited by daughter cells without changing the DNA Central nervous system brain and spinal cord 100 billion neurons even more glial cells Cell anatomy Plasma membrane selectively permeable biological membrane that separates the entire of all cells and their outside environment Nucleus contains genetic material Mitochondria powerhouse of the cell Ribosomes protein production Endoplasmic reticulum rough ER has ribosomes smooth ER functions in lipid and carbohydrate metabolism and detoxification Neurons are uniquely shaped electrically excitable cells that process and transmit info through electrical and chemical signaling Soma is where most usual cell stuff is Dendrites receive info Dendritic spines incr surface area for receiving info Axon branches out and sends info Connected to soma by axon hillock All mature cells have 1 or no axons Some have a myelin sheath white fatty stuff Speeds up transfer of info Spaces where there is no myelin Nodes of Ranvier 2 major kinds of neurons Sensory receptor neurons highly specialized to be sensitive to certain kinds of info o Ex Visual auditory Motor neuron receives info from other neurons Stimulates a muscle on a gland Afferent neuron carries info to another neuron or structure Usually sensory Efferent neuron carries info away from structure or another neuron Usually motor Most are interneurons intrinsic neuron entire neuron is inside a single structure amygdala gland organ They work both afferently and efferently Glial cells do not transmit info over long distances but are responsible for some chemical exchange In brain they take up the same amount of space as neuron but 1 10th of size Astrocytes do a lot of stuff o May wrap around wends of axons so neuron fires at all terminals at the same time o Chemical functions o Rid waste o Radial glial cells type of astro Very important during fetal development Guide mvmt and growth of neurons Many develop into astrocytes during fetal dvlpmt Some turn into neurons Microglial cells remove waste and remove viruses and bacteria Function as immune cells in brain Oligodendrocytes PNS Schwann cells provide myelin for axons During proliferation and differentiation less specialized cells reproduce more quickly and in greater number Ex Skin cells Neurons are the most differentiated cells of body For the most part you re born with all the neurons you ll ever have Glial cells are not this way They are always proliferating Brain cancer is usually from glial cells overproduction You may grow new neurons in your olfactory bulb and hippocampus Brain changes shape throughout life Neurons can add drop 3 of dendritic spines as much as they please More dendritic spines in enriched environments Alcohol doesn t kill brain cells but stunts dendritic branching