Genetics Chapter One 04 11 2013 Why bother Intelligence Facial expressions Sexual orientation Alcoholism Psychological disorders Weight gain Aggressive behaviors The Basics Chromosomes contain DNA Sequence of DNA gene A gene contains information on hereditary characteristics We have 46 chromosomes o 22 paired autosomal chromosomes o plus 2x female o or 1x and 1y male From DNA to Protein DNA RNA to be RNA RNA Protein o Transcription DNA seperates and a copy of one strand is made o Translation every 3 bases becomes an amino acid Genetic terms Homozygous and heterozygous Dominant and recessive PTC and taste A gene for a bitter receptor o Homozygous recessive tt cant taste PTC o Heterozygous Tt somewhat unpleasant o Homozygous dominant TT tastes horrible Sex linked genes The genes on the sex chromosome o Usually on the x Fragile x syndrome mental retardation Red green colorblindness Ducherine muscular dystrophy Hemophilia Sex Limited genes Present in both sexes but has an effect in only one sex Genes for chest hair breast size Genes are turned on under influence of sex hormones Estimate of how much of the variance in a characteristic is due to Heritability differences in heredity How do we know about heritability Twin studies o Identical twins share exact DNA o The more DNA they share the more likely you are to share the trait Suggests that the specific trait is heritable Twin studies MZ twins share chorion and blood supply so could be Adoption studies The big problem prenatal development genetics or could be prenatal environment Adoption studies prenatal environment Another problem with estimating heritability Genes predispose you to behaviors and to different treatment by others What started out as potentially small effect of genes end up having a huge behavioral result leading to overestimation of heritability Can environmental influences affect a trait with high heritability Yes inherited or genetic doesn t equal unmodifiable Evolution Natural selection Only heritable traits move on to next generation Evolution improvement o Based on environment genes are continued through generations of they aren t Epigenetics Changes in phenotype Cells of the Nervous System 2 1 04 11 2013 Cells of the nervous system Chapter 2 1 Mammalian Cells Cytoplasm and organelles Nucleus DNA ER Rough for translation smooth for transport modification of proteins Golgi finishing touches on new proteins Mitochondria energy production Lysosome Clean up Plasma membrane semi permeable barrier Phospholipid bilayer 2 layers of fat molecules that are free to float Cell membrane of neurons around one another Cells of the nervous system Semi permeable water oxygen carbon dioxide move freely Neurons 70 billion in just the cerebellum Glia way more of these cells then neurons play vital roles in functions of the nervous system 8 5 10x more glia than neurons Neurons Cells that receive and transmit information Basic unit of the nervous system Many neurological diseases are due to damage to a group of neurons PD a group of neurons in the CNS is called a nucleus Neuron The cell body is called the soma The branches coming off the soma are called dendrites they receive information The axon transmits the information through the neuron At the tips of the axon are axon terminal buttons goes to the dendrites of other neurons The myelin sheath convers the axon its insulation for the axon Motor neuron For example The cell body soma lives in the spinal cord The axon is part of a nerve in your body The terminals are in your muscles Somatosensory touch neuron For example The soma lives in a dorsal root ganglion just outside the spinal cord Most of its length is an axon It has specialized endings in the skin and its terminals are in the spinal cord Synapse where 2 cells meet The 2 neurons don t actually touch when they transmit information Presynaptic before the synpase Postsynaptic after the synapse efferent going away from afferent going towards synaptic cleft Dendritic spines Small protrusions on dendrites Location of most excitatory synapses Glia or Glial cells Exchange chemicals with neurons Oligodendrocytes Schwann cells makes myelin sheath in the PNS makes myelin sheath in CNS repair remove waste Microglia Radial Glia Astrocyte guide cell and axon migration during development perform many functions can wrap around synapses to contain environment wrap around a bunch of axons can make blood vessels get bigger to get extra nutrients to the neurons there used in blood brain barrier Blood Brain Barrier surrounds blood vessels that are feeding the brain Endothelial cells w tight junctions surrounding capillaries Astrocytes surround endothelial cells BBB keeps out o viruses bacteria o chemicals o nutrients BBB lets thru o small uncharged molecules like oxygen o fat soluble molecules vit A and D psychotropic drugs o glucose Sometimes viruses do enter Some brain regions have incomplete BBB on purpose Review parts of a neuron Study Questions Know the different organelles and their functions Understand the structure of the cell membrane Know the parts of a neuron and their functions Be able to label the parts of a neuron of the PNS Compare motor neurons sensory neurons How are they different from each other how are they the same Be able to draw each one Which one is multipolar and which one is unipolar Know the different types of glial cells and their functions ESPECIALLY which one puts myelin on axons in the CNS and which one myelinates axons Know the parts of a synapse presynaptic cell terminal postsynaptic cell dendrite or dendritic spine synaptic cleft Understand the terms afferent and efferent What where is the blood brain barrier What does it keep out let in What are the implications of this for drug use and medicine Inquiring minds Mammalian Cells Mammalian Cells Mammalian Cells Mammalian Cells Mammalian Cells Mammalian Cells Mammalian Cells Types of neurons Nolte Fig 1 4 Gross anatomy of the Brain 4 1 4 2 04 11 2013 Gross Anatomy of the Brain 4 1 4 2 Review and transition Parts of neuron o Dendrites soma axon terminals myelin sheath Gray matter versus white matter o The grey matter is the primarily cell bodies and dendrites o White matter is primarily axons Humans vs other mammals Bumps gyrus Smooth Same o Brain areas o Chemicals neurotransmitters o Proteins channels receptors Different o Overall brain size o Size of individual parts o Neocortex primates o Olfactory bulb rodents o Auditory cortex bats o Muscles and sense organs
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