BIOL 3240 Exam 1 | Questions and Answers (Complete Solutions)

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BIOL 3240 Exam 1 | Questions and Answers (Complete Solutions) What are the two major cell types in the brain? Neurons; glial cells What are some ways cell types can be defined? morphology; transcrip... tion profile; cell properties, function; context Two characteristics of neurons asymmetrical, excitable There are ____ major types of glial cell five A neuron is a post ____ cell Mitotic Neurons are both _____ and _____ excitable chemically, electrically _________ neurons have only one process that bifurcates into a dendritic end and an axonal end Unipolar Most neurons in invertebrates are _____ unipolar _____ neurons have two processes: one dendritic structure and one axonal. bipolar Many sensory neurons in vertebrates are ____ neurons bipolar _______ neurons start as bipolar, but the processes fuse into a single continuous structure that emerges from a single point on the soma. pseudo unipolar _____ neurons usually have a single axon and multiple dendritic structures Multipolar Where are pseudo unipolar neurons found? somatosensory system Most neurons in the human brain are Multipolar Neurons that connect sensory neurons to motor neurons are called Interneurons Neurons that integrate and process an electrical signal into a command signal are called Interneurons Neurons are often categorized based on their _____ in the brain Location The cytoskeleton of a neuron is made from what three filaments? microfilaments, neurofilaments, microtubules The diameter of neurofilaments is approximately ___ nm 10 What is the most abundant cytoskeletal component in neurons? neurofilaments There are three different neurofilament subunits: ___, ___, and ___ L, M, H There are ___ protofilaments in a protofibril (neurofilament composition) two There are ____ protofibrils in a neurofilament three Because of their stability, this cytoskeletal element provides strong architectural support to neurons neurofilaments Microtubules have a diameter of about ___ nm 25 This cytoskeletal element is highly dynamic microtubules ______ (cytoskeletal element) act as railway for distributing compounds in the cell, from the soma to the periphery Microtubules Microfilaments are made of ____ protofilaments 13 Each protofilament of a microtubule is a polymer of what heterodimers? alpha and beta tubulin Which of the cytoskeletal elements in a neuron is polar? Microtubules The negative end of the microtubule is oriented towards the ______ of the cell Center the positive end of the microtubule is oriented towards the _____ of the cell periphery Microtubules grow by addition of _____-bound tubular dimers at the ____ end GTP; plus A microtubule shrinks when its positive end is capped by GDP bound tubulin In neurons, Mts are stabilized by what proteins? Microtubule associated proteins (MAPs) Which MAP is present in dendrites? MAP2 Which MAP is present in axons? MAP3 What other MAP is present in axons besides MAP3? Tau Microfilaments have a diameter of around __ to ___ nm 3 to 7 Where are microfilaments concentrated in neurons? Periphery Microfilaments and their associated proteins form a dynamic network underlying _______ _______ Growth cones Microfilaments are short and unstable to ensure ________ _______ of neurons rapid growth Microfilaments are made of two strands of _____ forming a double stranded ______ actin; helix Microfilaments are (stable/unstable) and go through rounds of ____________ and depolymerization unstable; polymerization Where would you expect to find microfilaments on a neuron? Dendrites, synapse Where would you expect to find neurofilaments? Axon What microtubule binding protein is associated with Tau tangles? Tau Protein aggregates are toxic and are associated physiologically/clinically with a drastic loss in what? brain mass In normal neurons, Tau is either bound to ______ or is free in the _____ MTs, cytosol This is a picture of what protein aggregate? Tau Tangle This is a picture of what protein aggregate? Lewy body This is a picture of what protein aggregate? B amyloid plaque (active/passive) cellular transport is required for normal neuronal function active ______ transport refers to movement towards the periphery Anterograde _______ transport refers to movement towards the soma Retrograde T or F: Axonal transport can be fast or slow True What is the speed of fast axonal transport? 50 to 400 mm/day T or F: fast axonal transport is bidirectional True Anterograde fast transport is mostly used to do what? Replenish synaptic sites Retrograde fast transport is mostly used to do what? Send synaptic material to lysosomes for degradation Retrograde fast transport is used to carry what types of activity signals to the soma? transcription or growth factors What is the speed of slow axonal transport? 0.2 to 5 mm/day Slow axonal transport is (uni/bi) directional unidirectional Slow axonal transport is only (anterograde/retrograde) anterograde What is slow axonal transport used for? carrying cytoskeletal proteins What proteins carry out slow axonal transport on microtubules? Kinesins Oligodendrocytes insulate neurons in the (CNS/PNS) CNS Schwann cells insulate neurons in the (CNS/PNS) PNS _______ is a bimolecular layer of ____ (mostly phospholipids and cholesterol) interspersed between layers of protein Myelin; lipid The thickness of the myelin sheath is (proportional/inversely proportional) to the diameter of the axon Proportional Small axons are / are not often myelinated are not T or F: one oligodendrocyte produces many myelin sheaths True Schwann cells produce (one/many) myeline sheath one What is the size of a node de Ranvier? 1 mm _______ (glial cell) maintain homeostasis by regulating ion concentration and neurotransmitters in extracellular space astrocytes Astrocytes have a large number of thin processes that enfold all _____ ____ and sheath ______ blood vessels; synapses Astrocytes buffer ____ ions by taking up the ions released at the synapses and releasing them into blood vessels K+ Astrocytes take up neurotransmitters and_____ them into their molecular precursors Degrade _______ ______ (glia) produce and move CSF ependymal cells Cells of the choroid plexus filter ______ from blood and secrete this filtrate into the ventricles as ______ plasma; CSF Choroid plexus cells are specialized ______ cells (glia) Ependymal The main function of _______ (glia) is to provide ______ to the brain from injury and infection Microglia Microglia are derived from ____ _____ and invade the brain early during _______ bone marrow; development Microglia are highly _______ and can squeeze into the _____ _____ barrier migratory; blood brain What is one way microglia provide immunological surveillance? secrete cytokines and chemokine, phagocytose debris Rapid changes in membrane potential are possible because of specialized membrane proteins ______ ________ establish and maintain membrane potential by maintaining the gradient of ions across the membrane ion channels ____ _____ generate rapid changes in membrane potential ion pumps The concentration of Na+ is higher (in/out) of the cell Out The concentration of K+ is higher (in/out) of the cell In The concentration of Cl- is higher (in/out) of the cell Out The concentration of Organic Anions is higher (in/out) of the cell In Charges separate at the membrane, creating a difference in electric potential Most neurons have a resting membrane potential of -65 to -80 mV Ions cannot diffuse across the bilayer unless energy is expended to overcome their attraction to _____ molecules H2O The smaller the crystal radius of an atom is, the _______ its attraction to H2O stronger Which ion will have a bigger water cage, Na+ or K+? Na+ Which ion will have a bigger water cage, Na+ or Cl-? Na+ ______ have an aqueous pore that, when open, allows specific molecules, like ions, to pass through Channels ______ have two separate gates that open and close sequential so that soluble molecules move from one side to the other side Pumps What are the the three properties of ion channels? Gating, selectivity, conductance Gating of ion channel some ion channels open/close in response to a signal Selectivity of an ion channel ion channels recognize and select for a specific ion Conductance ion channels conduct ions across the membrane In an ion channel, the transition between open/closed state requires energy and is called Gating In an ion channel, transitions between conformation are immediate, on the scale of Microseconds If not in their open state, a gated ion channel can be resting; refractory A resting ion channel is closed and activable A refractory ion channel is closed and inactivable Ligand-gated ion channels open using the ________ that results from the binding of a ligand change in free energy (deltaG) A ligand gated channel enters _____ phase when exposure to ligand is prolonged, a process known as _________ refractory; desensitization Common ligands include neurotransmitters, ATP, PIP2, Zinc Voltage-gated channels open with energy provided by ________ through the electric field across a membrane movement of voltage sensor the refractory period of Na+ and K+ ion channels is caused by _______ _______ conformational change the refractory period of Ca2+ ion channel is caused by the binding of Ca2+ to an internal regulatory site Humans have voltage-gated ion channels specific for Na+, K+, Ca2+, cyclic nucleotides, proteins The smaller the radius of an ion, the more ______ its charge and the (stronger/weaker) it attracts H2O localized; stronger Which ion channel has a larger pore, K+ or Na+? Na+ Which channel can select based on ion size, K+ or Na+? K+ Na+ ions, in an ion channel, interact with binding sites of ____ negative field strength high K+ ions, in an ion channel, interact with binding sites of _____ negative field strength low How many binding sites are present in a K+ channel? 5 When a Na+ channel is open, what direction do ions move? inside the neuron When a K+ channel is open, what direction do ions move? outside the neuron At most, how many K+ ions can occupy the K+ ion channel binding sites? 3 The flux of ions through an ion channel is (active/passive) Passive What two forces drive the flux of ions through an ion channel? chemical, electrical What gradient is formed by the net movement of ions through ion channels? Electrochemical gradient The flux of ions across a channel can be blocked by non physiological or rare physiological molecules that bind to either the mouth or pore of a channel. What are some examples of physiological molecules that block ion channels? Mg2+, polyamides The flux of ions across a channel can be blocked by non physiological or rare physiological molecules that bind to either the mouth or pore of a channel. What are some examples of non-physiological molecules that block ion channels? toxins, drugs The electrochemical gradient is established mostly by ion pumps In what two ways do ion pumps differ from ion channels? pumps move ions by undergoing conformational changes; pumps use energy (ATP) to drive transport Give two examples of primary transporters Na+/K+ pump; Ca2+ pump The Ca2+ pump moves Ca2+ (with/against) its electrochemical gradient Against The Na+/K+ pump moves ions (with/against) their electrochemical gradient against [Show More]

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