BIO 212 Exam 4

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Nervous System Functions
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Sensory inputs Motor responses Autonomic functions Learning and cognition Info collection, processing, and responses
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Central Nervous System (CNS)
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Brain and spinal cord
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Peripheral Nervous System (PNS)
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All neurons and their projections that are outside of the CNS
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Dendrites
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Collect chemical signals
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Cell Body
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Integrates incoming signals and generates outgoing electrical signal to axon
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Axon
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Passes chemical signals to dendrites of another cell or to an effector cell
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Glial Cells
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Multifunctional More numerous than neurons May function as stem cells to produce more glial cells and neurons Myelin sheath interrupted by nodes of Ranvier
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Astrocytes
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Metabolic support
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Microglia
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Remove cellular debris
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Sensory Neurons
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Detect info from outside world or internal body conditions Afferent neurons-transmit to CNS
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Motor Neurons
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Send signals away from CNS (efferent neurons) to elicit response
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Interneurons or Association Neurons
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Form interconnections between other neurons in the CNS
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Membrane Potential
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Every cell has a voltage (difference in electrical charge) across its plasma membrane When an electrical potential exists on either side of a plasma membrane Separation of charges Generally more negative ions on inside of plasma membrane
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Resting Potential
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Membrane potential of a neuron at rest, not sending signals
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Cells are electrical by nature…
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…Ions on both sides of the plasma membrane create an electrical potential
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All cells have a membrane potential…
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…due to differences in ion concentrations inside the cell relative to the extracellular space
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A cell’s resting potential is determined by…
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…differences between intracellular and extracellular ion concentrations
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In a mammalian neuron at resting potential, the concentration of K+ is greater inside the cell…
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…while the concentration of Na+ is greater outside of the cell
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How do neurons establish differential concentrations of ions inside and outside the cell?
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Active transport
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Combined effects produce electrochemical gradients =
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Membrane potential
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3 Factors contribute to resting potential
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1. Na+/K+ -ATPase (sodium potassium pump) transport 3 Na+ out of every 2 K+ moved in 2. Ion specific channels allow passive movement of ions (many more ungated K+ channels than ungated Na+ channels, membrane more permeable to K+ at rest) 3. Negatively charged molecules such as proteins more abundant inside cell
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Equilibrium Potential
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Electrical charge maintained by chemical gradient
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Opposing forces of chemical and electrical gradients can create…
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…an equilibrium where there is no net movement
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Electrical charge gradients–>
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Seek equilibrium
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Chemical concentration gradients–>
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Seek equilibrium
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All cells have a…
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…membrane potential
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Only neurons and muscle cells are excitable…
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…capacity to generate electrical signals
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Depolarization
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Cell membrane becomes less polarized Cell becomes less negative
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Hyperpolarization
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Cell membrane becomes more polarized Cell becomes more negative
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The inside of a resting neuron is negatively charged. Where is the [K+] higher?
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Inside the cell
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The major signaling cell of the nervous system is the ____.
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Neuron
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Which of the following contribute to the resting potential of a neuron? A. Bulk flow B. Voltage gated Cl- channels C. Ungated ion specific “leak” channels D. Anions in the cytoplasm E. Na+/K+ pump F. Ligand gated Na+ channels
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C,D,E
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Voltage Gated Ion Channels
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Open and close in response to voltage changes
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Ligand Gated Ion Channels
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Open and close in response to ligands or chemicals
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Action Potential Sequence
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1. Resting potential 2. Graded potential 3. Action potential 4. Repolarization/hyperpolarization 5. Return to resting potential
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1. Resting potential
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Voltage gated ion channels are closed
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2. Graded potential
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Depolarizes membrane to threshold potential Less negative charge inside cell Voltage gated Na+ channels open
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3. Action Potential
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Na+ rapidly diffuses into cell, brining + charge Further depolarization opens even more voltage gated Na+ channels-positive feedback Then Na+ channels become inactivated and K+ channels open
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4. Repolarization/Hyperpolarization
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Na+ channels close K+ channels remain open K+ diffuses out of cell and membrane become negative again So much K+ leaves cell it causes hyperpolarization
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5. Return to resting potential
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Voltage gated ion channels close
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Refractory Period
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Membrane cannot mount an action potential Na+ channels inactive, K+ channels open
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All action potential for a given neuron are…
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…identical in magnitude and duration
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Action potentials are propagated…
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…down the length of the axon
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Na+ channels are more likely to open as a membrane depolarizes, leading to…
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…the opening of additional Na+ channels, and further depolarizing the membrane-positive feedback
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There is no such thing as a partial action potential…
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…the result is an “all or none” signal
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The action potential depends on a voltage gated ion channel that…
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…open and close in response to changes in membrane voltage
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Patch Clamping
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Allows the study of a single ion channel
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Using patch clamping, researchers determined that…
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…1. Voltage gated channels are either open or closed 2. Na channels open quickly after depolarization 3. K channels open with a delay after depolarization
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Initiation of an action potential involves…
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…Na+ channel opening
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Repolarization and return to the resting potential involves…
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…Voltage gated Na+ channel inactivation and Opening of the voltage gated K+ channels
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Action Potential Conduction
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Graded potential reach threshold potential at axon hillock Triggers opening of voltage gated Na+ channels just beyond hillock region Depolarizes area further along axon Sequential opening of Na+ channels conducts a wave of depolarization from axon hillock to axon terminal Inactivation gate of Na+ channels prevent backward movement toward cell body
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The disease Multiple Sclerosis develops as…
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…damage to myelin increases and electrical signaling is impaired, causing the muscles to weaken and coordination to lessen
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Chemical Synapse
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1. Action potential arrives near synaptic cleft 2. Voltage gated Ca2+ channels open, Ca2+ enters presynaptic cells 3. Synaptic vesicles fuse with presynaptic membrane, then release neurotransmittter 4. Ion channels in the post synaptic membrane open when neurotransmitter binds;flow of ions causes change in postsynaptic cell potential 5. Ion channels in the postsynaptic membrane then close as neurotransmitter is broken down or taken back up by presynaptic cell
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Postsynaptic Receptors
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Ligand gated ion channels open in response to neurotransmitter G protein coupled receptors initiate changes in postsynaptic cell
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In some cases, the same neurotransmitter can have excitatory or inhibitory effects on different post synaptic cells..how?
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Response of postsynaptic cell depends on postsynaptic receptor type expressed
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The difference in charge across the plasma membrane of an unstimulated neuron is called_______.
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The resting membrane potential
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A neuron has reached a threshold potential when it has depolarized to the point where…
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…sufficient numbers of voltage gated Na+ channels open to initiate a positive feedback loop, contributing to further depolarization
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Postsynaptic Response
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1. EPSPs bring the membrane potential closer to the threshold 2. IPSPs take the membrane potential further from threshold 3. Simultaneous EPSPs and IPSPs cancel each other out
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The size of an EPSP or IPSP depends on…
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…the amount of neurotransmitter that is released at the synapse
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Both types of signal are short lived because…
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…Neurotransmitters do not bind irreversibly to channels in the postsynaptic cell
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Neurons typically make…
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…hundreds or thousands of synapses with other cells
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At any instant, the EPSPs and IPSPs that occur at each of these synapses lead to…
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…short lived changes in the membrane potential of the post synaptic cell
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If an IPSP and an EPSP occur close together in space or time…
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…the changes in membrane potential tent to cancel each other out
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If several EPSPs occur close together…
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…they sum and make the neuron likely to fire an action potential
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Summation
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The additive nature of EPSPs and IPSPs
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Diencephalon
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Info relay to cerebellum Control of homeostasis
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Brain Stem
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Info relay to spinal cord Autonomic control of heart, lungs, digestive system
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Cerebellum
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Coordinates complex motor patterns
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Cerebrum
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Conscious thought Memory
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Learning
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Process by which new info is acquired
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Memory
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Involves retention of that info over time Process in 2 phases-short and long term memory
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Short Term Memory
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Lasts for minutes or hours Typically single stimulus Intracellular 2nd messengers make it easier for neurons to communicate No new proteins synthesized
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Long Term Memory
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Lasts days or weeks Repeated stimuli Activates genes, leads to mRNA synthesis, new proteins for additional synaptic connections
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Synaptic Plasticity
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Change in synapses due to learning
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Neurogenesis
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Genesis of new neurons
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Plant Stomatal Control
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Essential for gas exchange, photosynthesis, water and mineral transport, and water conservation
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Transduction
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Conversion of an external stimulus to an internal signal in the form of a neural signal
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Amplification
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Amplify signal
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Transmission
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Transmit signal to CNS
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Perception
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Different stimuli produce different sensations because they activate specific neural pathways dedicated to processing only that type of stimulus
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Nociceptors
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Sense harmful stimuli such as tissue injury
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Thermoreceptors
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Detect changes in temperature
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Mechanoreceptors
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Respond to distortion caused by pressure
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Chemoreceptors
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Perceive the presence of specific molecules
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Photoreceptors
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Respond to particular wavelengths of light
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Electroreceptors
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Detect electrical fields
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Magnetoreceptors
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Detect magnetic fields
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Sensory Receptor
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Recognizes stimulus and initiates signal transduction by creating graded potentials in itself or adjacent cells When response is strong enough, an action potential is sent to CNS
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Topographic Representations
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Different sensory inputs and motor outputs map to specific regions of the cerebral cortex
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Intensity
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When a stimulus is strong enough, it will depolarize the membrane to the threshold potential and produce an action potential in a sensory neuron
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Strength of Stimulus
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Strength of stimulus is indicated by the frequency of action potentials generated Strong stimulus generates more action potentials in a shorter amount of time Brain interprets higher frequency of action potentials as a more intense stimulus
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Post synaptic cells…
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…often contain neurotransmitter receptors
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The response of a post synaptic cell is determined by…
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…The type of neurotransmitter released at the synapse The type of receptors the postsynaptic cell has The number of Na+ channels in the postsynaptic membrane The number of K+ channels in the postsynaptic membrane
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Sensory neurons…
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…produce different frequency of action potentials depending on intensity of a stimulus
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Which is involved in depolarizing a neuronal membrane during an action potential?
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Opening voltage gated Na+ channels
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A reason that the same neurotransmitter can have excitatory effects on some postsynaptic cells and inhibitory effects on other is…
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…different neurons express different proteins
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Muscle
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Cells specialized to contract generating force for movement
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Skeletal Muscle
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Attached to bone or exoskeleton for locomotion Voluntarily controlled
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Smooth Muscle
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Surrounds hollow tubes and cavities for propulsion of contents Involuntarily controlled
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Cardiac Muscle
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Only in heart Involuntarily controlled
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Myofibrils
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Small strands in muscle fibers Made up of light and dark areas known as sarcomeres
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Sarcomere
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Becomes shorter as the myofibril contracts and longer when the sarcomere relaxes Repeating units of actin and myosin fibers Basic contractile unit of muscles
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Muscle cell contains myofibrils…
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…cylindrical bundles of actin and myosin proteins assembled in a highly ordered manner
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Sarcomere is made up of 2 types of proteins…
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…actin-thin filaments myosin-thick filaments
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Thin Filaments
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Composed of 2 coiled chains of the globular protein actin One end of each thin filament is bound to the Z disk, which forms the end of the sarcomere and anchors the filament Other end is free to interact with thick filament
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Thick Filaments
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Composed of several strands of myosin Has head and tail subunits
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Muscle Contraction
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Sliding filament mechanism Myosin cross bridges (heads) attach to actin and pull thin filament toward center of sarcomere Cross bridge repeats motion as long as stimulation to contract continues Sarcomere shorten as thin filaments slide past stationary thick filaments
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Model for Actin Myosin Interaction
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1. ATP binds to myosin head. Head releases from thin filament 2. ATP hydrolyzed. Head pivots, binds to new actin subunit 3. P released. Head pivots, moves filament 4. ADP released. Cycle is ready to repeat
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Muscle Relaxed
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Tropomyosin and troponin work together to block the myosin binding sites on actin
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Contraction Begins
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When a calcium ion binds to troponin, the troponin tropomyosin complex moves, exposing myosin binding sites
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How do action potentials trigger muscle contraction?
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1. Action potential arrives, releases acetylcholine 2. Acetylcholine binds to acetylcholine receptors 3. Action potentials propagate across plasma membrane and into muscle cell via T tubules 4. Ca2+ channels open into sarcoplasmic reticulum 5. Ca2+ is released. Sarcomeres contract
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If cytosolic Ca2+ levels are high…
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…muscles will contract (as long as there is adequate ATP)
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Ca2+ is stored in, and released from…
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…the sarcoplasmic reticulum (membrane network that surrounds myofibrils)
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Ca2+ release triggers contraction…
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…Ca2+ released into cytosol Binds regulatory proteins on actin, opens binding sites and triggers contraction
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Ion pumps return Ca2+ to SR, regulatory proteins move back to cover binding sites on actin…
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…and contraction stops
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Smooth Muscle Cell Characteristics
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Located in intestines, arteries Move food, help regulate blood pressure Single nucleus Unstriated Unbranched No sarcomeres Activity is involuntary
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Cardiac Muscle Characteristics
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Located in heart Pumps blood 1 or 2 nuclei Striated Branched-intercalated discs form direct cytoplasmic connection end to end Contains sarcomeres Activity is involuntary
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Skeletal Muscle Characteristics
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Attached to skeleton Moves skeleton Multinucleated Striated Unbranched Contains sarcomeres Activity is voluntary
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Skeleton Functions
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Support, protection, locomotion
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3 Types of Skeletons
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Hydrostatic (combo of muscles and fluid) Exoskeleton (external, chitin, segmented for movement) Endoskeleton (internal, bone/cartilage, minerals give firmness)
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Basic Structure of Hydrostatic Skeletons
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Composed of a body wall surrounded by a fluid, or deformed tissue under compression
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How do hydrostatic skeletons move?
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1. Muscles contract, making segments narrow 2. This squeezes the internal fluid, increasing the internal pressure 3. Pressure pushes outward, extending the relaxed longitudinal muscles 4. Longitudinal muscles contract and circumferential muscles relax
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Peristalic Wave
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Alternating relaxation and contraction of the 2 muscle layers causes a wave
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Antagonistic Muscle Group
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2 layers of muscle, longitudinal and circumferential
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Exoskeleton Charcteristics
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Made of chitin Jointed with paired extensor and flexor muscles
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Endoskeleton Characteristics
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Composed of connective tissues, cartilage, and bone Bones meet and interact at articulations, or joints Allow bones to swivel, hinge, or pivot
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Cartilage
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Made up of cells scattered in a rubbery gelatinous matrix
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Bone
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Made up of cells in a hard extracellular matrix of calcium phosphate Living, dynamic tissue Vascularized, innervated Mineralized extracellular matrix Marrow of some bones produces blood Hematopoetic stem cells
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Tendons
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Attach muscles to bones Bands of tough, fibrous connective tissue
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Ligaments
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Fibrous tissue that binds the bones
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Muscle exerts a force on bones at a joint…
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…muscles that bend limb are flexors Muscles that straighten limb are extensors
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Which region corresponds to the myosin filaments?
Which region corresponds to the myosin filaments?
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Dark center stripes
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Which of the following does NOT happen during a muscle contraction? A. Myosin heads bind to actin B. Thick and thin filaments shorten C. Myosin heads pull the thin filaments toward the center D. Sarcomere shortens E. Myofibril and muscle shorten
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B. Thick and thin filaments shorten
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In terms of muscle contraction, what would happen if ATP were depleted?
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Myosin would not release from actin
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Calcium in skeleton muscle cells…
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…regulates availability of myosin binding sites on actin
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Which of the following choices is not a part of how voluntary muscle contraction is regulated? A. Acetylcholine is released at a neuromuscular synapse B. ATP is released from a sarcoplasmic reticulum C. Neurotransmitter binds ligand gated channels that allow influx of Na+ to depolarize the muscle cell membrane D. Ca2+ binds troponin/tropomyosin to uncover myosin binding sites on the actin
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B. ATP is released from the sarcoplasmic reticulum
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Hydrostatic skeleton is one in which…
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…fluid under pressure is used
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Muslce increases due to…
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…exercise are mainly due to increased # of myofibrils More actin and myosin, few cells added
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Pathogenic Disease
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Viruses, bacteria, fungi, parasites
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Genetic Disease
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Hereditary diseases, birth defects Somatic mutations–>cancer
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Deficiency Disease
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Ricketts, osteoporosis, anemia
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Physiological Disease
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Metabolic imbalances Psychological disorders Prions
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Environmental Exposure/Toxins
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Black lung, asbestosis, emphysema, liver sclerosis
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Pathogens
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Biotic agents that cause disease in their hosts Viruses and viroids Bacteria and mycoplasmas Fungi Other parasites
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Viruses
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Not alive Not cells-cannot carry out metabolism or synthesis Do not respond to antibiotics Hijack host’s cells Require living host cells to reproduce Consist of nucleic acid genomes enclosed in protein coats
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Virus Characteristics
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DNA or RNA, can be single stranded or double stranded No plasma membrane Can’t carry out transcription independently Can’t carry out translation independently Virtually no metabolic capabilites
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Epidemic
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Disease that rapidly infects a large number of individuals over a widening area
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Pandemic
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Worldwide epidemic
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Virus Basic Structure
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Genome-DNA or RNA, linear or circular Capsid-protein coat Envelope-derived from host cell plasma membrane
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Capsid serves 2 functions
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Protects genome while outside host cell Releases genome when infecting a new cell
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Viruses infect host cell in 1 of 2 ways
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Via replicative growth-produces next generation of virions, often kills host cell In a dormant manner-suspends virion production, allows the virus to coexist with the host for a period of time
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6 Phases Common to Replicative Growth
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1. Attachment to a host cell and entry into cytosol 2. Viral genome transcription and viral protein production 3. Viral genome replication 4. Assembly of a new generation of viruses 5. Exit from infected cell 6. Transmission into a new host
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Bacteriophage
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Virus that infects bacterial cells
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Lytic Cycle (replicative growth)
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1. Viral genome enters host cell 2. Viral genome is transcribed, viral proteins are produced 3. Viral genome is replicated 4. Particles assemble inside host cell 5. Particles exit to exterior
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Lysogeny
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1. Viral genome enters host cell 2. Viral genome integrates into host cell genome 3. Host cell DNA polymerase copies chromosome 4. Cell divides. Virus is transmitted to daughter cells OR 4. At any point after integration, the virus may activate the replicative cycle
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Lytic Cycle
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In rapidly dividing cells Takes over cell, produces many infectious viruses Ruptures the cell to release the viruses
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Lysogenic Cycle
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In slowly growing cells Virus DNA integrates into host genome and become latent Virus replicated along with host Favorable growth conditions trigger excision and the lytic cycle
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Genomic reassortment generates new influenza strains
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1. 2 different strains of influenza infect the same cell 2. Replication produces a mix of strain specific genomic segments inside host 3. Reassortment of segments generates new, recombinant strains
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The smallest contractile unit in skeletal muscle is the___________.
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Sarcomere
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What would occur if the uptake of calcium ions was blocked in the sarcoplasmic reticulum?
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Sustained muscle contraction
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What causes rigor mortis?
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Calcium facilitating actin-myosin cross bridges in the sarcomeres, creating a constant state of muscle contraction
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Most biologists agree that viruses are not living organisms, in large part because…
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…they are not cellular
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How does HIV cause disease?
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Destroys helper T cells Immune system is weakened Kills people indirectly
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HIV Infection
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1. Attachment-virus binds CD4 receptor on helper T cell surface 2. Entry-virus envelope fuses with cell membrane and capsid released into cell 3. Integration-RNA genome is reverse transcribed to DNA, then integrated into host cell genome 4. Synthesis of viral components-HIV genome while in host chromosome is transcribed-viral RNA is translated to make viral proteins 5. Assembly-viral RNA is packaged with reverse transcriptase into protein capsid-some viral proteins are inserted into host plasma membrane 6. Release-capsid is enveloped in host plasma membrane and virus is budded off from cell
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HIV is hard to cur
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Integrated into host genome Currently impossible to eliminate May remain dormant for long periods of time Reverse transcriptase lacks a proofreading function Makes errors and tends to create mutant strains of HIV Makes it difficult to create vaccine
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All organisms are targets for diseases from pathogens…
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…disease causing organisms Bacteria, parasites, viruses, fungi, protists
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Immunity
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Resistance to or protection against disease causing pathogens Prevents individuals from contracting a disease more than once
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Immunization
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Conferring of immunity to a particular disease
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Vaccination
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Introduction of a weakened or altered pathogen to prime the body’s immune system, so it fights later infection effectively
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Surface coverage is the first line of defense…
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…Body is protected from pathogens by the skin and mucous membranes Skin Mucous membranes contain lysozymes Other cells contain cilia which can filter pathogens and particulates
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Cells
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Many types fight pathogens Mechanisms inside each cell that prevent infection
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Secreted Products
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Antibodies Signaling molecules Antibacterials
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Innate Immunity
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Immune system cells that are ready to respond to foreign invaders at all times Nonspecific and responds in same way to all antigens
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Antigens
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Any foreign molecule that can initiate an immune response
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Adaptive Immunity
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Cells that require activation Cells respond in an extremely specific way to the particular invader Slow response
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Phagocytic Cells
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Important for innate immunity Engulf particulate matter and destroy it Most are leukocytes Recognize some general feature such as a bacterial surface protein
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Mast Cells
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Secrete histamine
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Endothelial Cells
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Secrete nitric oxide
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Neutrophils and other phagocytes…
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…engulf and destroy bacteria
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The Inflammatory Response
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1. Pathogens enter wound 2. Platelets release blood clotting proteins 3. Injured tissues and macrophages release chemokines to recruit help 4. Mast cells release factors that constrict blood vessels at wound and dilate vessels nearby 5. Neutrophils arrive andd begin phagocytosizing pathogens 6. Other leukocytes arrive and mature into macrophages
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Viruses use the host cell…
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…to copy themselves and make viral proteins
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When people die from HIV infections, it is usually because they…
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…have too few T cells to adequately fight infection
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What is the difference between and epidemic and a pandemic?
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An epidemic is restricted to a local region; a pandemic is global
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Which of the following supports the argument that viruses are nonliving? A. They do not evolve. B. They lack genetic material C. They are not cellular D. Their DNA does not encode proteins E. They have RNA rather than DNA
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C. They are not cellular
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What would you expect in an individual who contracted the HIV virus within the past 5 weeks?
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A rapidly declining helper T cell concentration, because the virus reproduces quickly, before the immune system can mount a defense
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The innate immune system…
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…recognizes general non self signals Includes cells that will engulf and destroy particles
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The adaptive immune response…
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…AKA acquired immune response Based on interactions between specific immune system cells and a specific antigen
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Antibodies
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Proteins that are produced and secreted by certain lymphocytes Bind only to a specific part of a specific antigen
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4 Key Characteristics of Adaptive Immune Response
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Specificity Diversity Memory Self-nonself recognition
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Specificity
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Antibodies and other components of the adaptive immune system bind only to specific sites on specific antigens
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Diveristy
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Adaptive response recognizes an almost limitless array of antigens
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Memory (immune response)
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The adaptive response can be reactivated quickly if it recognizes the antigens from a previous infection
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Self-nonself Recognition
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Molecules that are produced by an individual do not act as antigens, adaptive immune system needs to be distinguished between self and nonself
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Lymphocytes
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Cells involved in adaptive immune response
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Adaptive immunity is involved in…
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…disease resistance Allergies Autoimmune disease Histoincompatibility Comprised in AIDS
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B Cells
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Synthesize and secrete antibodies Differentiate into plasma cells
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Plasma Cells
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Secrete antibodies
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T Cells
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Cytotoxic-directly kill antigen bearing cells Helper T-activate B cells and cytotoxic T cells
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Genetic Recombination
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1. Start with full complement of V,J, and C segments 2. Recombine (1 V, 1 J, and the C) 3. Transcription and RNA processing 4. Translation
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Clonal Selection Theory
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1. Each lymphocyte has thousands of copies of a unique receptor on its surface-receptor recognizes only one antigen 2. The lymphocyte is activated when it binds to its specific antigen 3. An activated lymphocyte divides, makes many copies of itself-specific cells selected and cloned in response to an infection 4. Some of cloned cells descended from an activated lymphocyte persist after the pathogen is eliminated and allow a rapid response if the infection recurs
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MHC Antigen Presentation
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1. Dendritic cell ingests antigen via phagocytosis 2. Enzymes break antigen into peptide fragements 3. Peptides are loaded onto MHC in endosomes 4. MHC-peptide complex is transported to cell surface 5. MHC protein presents peptide on cell surface
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T Cell Activation
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1. T cell receptor binds to antigen presented on MHC, becomes activated 2. Activated T cells multiply, differentiate, and enter blood
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B Cell Activation
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1. B cell recognizes invader 2. B cell stimulates active T cell 3. B cell is activated by helper T cell 4. Activated B cell divides, produces plasma cells, which produce antibodies
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During development, each B cell lymphocyte undergoes unique gene rearrangements to…
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…encode unique membrane receptor that can bind to a specific antigen
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Each B cell is…
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…specific for just 1 type of antigen
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Binding the antigen induces cell division—>
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clones
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B Cell Differentiation
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Cell specializes to produce and secrete large amounts of antibody proteins
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Primary Immune Response
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Initial exposure to an antigen Antibody production is slower and lower
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Secondary Immune Response
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Repeat exposure to same antigen Memory B cells quickly stimulated to multiply and differentiate Faster and larger antibody response
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Which of the following are examples of antigens? A. One of a group of proteins found in the blood that leads to the clumping of foreign blood cells B. Proteins embedded in the membranes of T cells C. Foreign molecules that trigger antibody production D. Proteins that trigger the end of the inflammatory response
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C. Foreign molecules that trigger antibody production
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A function of B cells is to…
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…produce antibodies
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Antibody diversity is produced by…
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…gene recombination
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After an initial infection, vertebrates often become immune to the same pathogen because…
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…memory B cells mount a strong and rapid secondary response
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Lupus is a disease in which the body’s immune system attack healthy tissue. What has occurred?
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An autoimmune response
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3 Steps of Info Processing in Plants
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1. A receptor cell receives an external signal 2. The receptor cell sends a signal to cells in another part of the plant 3. Responder cells receive the signal-results in a change in the plant’s activity
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R Genes
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Specific resistance involves resistance genes
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Elicitors
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Produced by pathogens Compounds that promote infection in plant tissue
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Elicitors recognized by R gene products…
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…triggers hypersensitive response
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Hypersensitive Response
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Localized programmed cell death around site of infection Synthesis of hydrolytic enzymes, defensive metabolites, defense hormones, and tough lignin in cell walls of surrounding tissues Inhibits spread of infection
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Other hypersensitive defense responses include…
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…closure of stomata Production of toxins molecule that target pathogens Reinforcement of the cell wall to prevent movement of pathogens
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Meiosis leads to…
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…production of gametes Daughter cells have half the amount of genetic material as the parent cell
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Mitosis leads to…
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…production of all other cell types (somatic cells) Genetic material is copied and then divided equally Daughter cells are genetically identical to the parent cell
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How many Americans are diagnosed with cancer each year?
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About 1.5 million
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How many Americans are likely to die from cancer each year?
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About 0.5 million
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What are the odds that you will have cancer at some point in your lifetime?
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1 in 3 for women 1 in 2 for men
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Cancer
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Disease of multicellular organisms that is characterized by uncontrolled cell division 2nd leading cause of death 10% are hereditary 90% don’t involve genetic changes from parent
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Carcinogens
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Agents that increase the likelihood of developing cancer UV light, cigarette smoke-cause mutations in somatic cells
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Cancers
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Originate from a single cell Mutate so cells grow abnormally
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Tumor
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Overgrowth of cells with no useful purpose
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Benign Tumor
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Don’t spread Mass of cells that lacks ability to invade neighboring tissue or metastasize
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Malignant Tumor
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Lost normal growth regulation Invades healthy tissue Metastatic-can migrate into other parts of body Will cause death if untreated
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Oncogenes
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Viruses can carry these into host cell in viral genome
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3 Outcomes of Mutations
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1. Mutation has no effect on genes/function of cell 2. Mutation affects a gene that is critical for cell function and survival 3. Mutation affects a gene that regulates a process such as the cell cycle, such that it gives the cell a survival advantage over its neighbors
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Cancer can arise from mutations in genes that…
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…promote DNA repair Control cell division Required for apoptosis Involved in immune responses
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Cell Cycle
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Regulation controls cell division
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G1 Phase
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Essentially eliminated in rapidly dividing cells
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Variations in cell cycle length suggest…
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…cell cycle is regulated Regulation varies among cells and organisms
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Positive Regulators
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Promote cell division Growth factor signaling Signal transduction pathway activates cell cycle
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Negative Regulators
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Checkpoint control molecules
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Checkpoint Proteins
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Cyclins and cyclin dependent kinases responsible for advancing cell through phases of cell cycle
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3 Cell Cycle Checkpoints
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G1 G2 M
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Pass G1 checkpoint if…
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…cell size is adequate Nutrients are sufficient Social signals are present DNA is damaged
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Pass G2 checkpoint if…
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…Chromosomes have replicated successfully DNA is undamaged Activated MPF is present
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Pass M phase check point if…
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…chromosomes have attached to spindle apparatus Chromosomes have properly segregated and MPF is absent
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If there is a problem…
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…cell cycle will be arrested until damage is repaired Cell will undergo apoptosis
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Cancer is caused by…
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…growth in an uncontrolled fashion Cells invading nearby tissues Spreading to other sites in the body
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Social Control
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Cells respond to signals from other cells Divide only when their growth benefits the whole organism Based on growth factors
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Growth Factors
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Small proteins released by cells that stimulate division in other cells Cell cultures will not grow unless these are present
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Cancer cells no longer subject to social control at the…
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…G1 checkpoint
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Oncogenes
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Mutation causes a gene to be overactive-have abnormally high level of expression Overactivity contributes to uncontrolled cell growth
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Tumor Suppressor Genes
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When normal encodes proteins that prevents cancer When mutated, causes loss of activity-uncontrolled growth can occur
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Proteins encoded by tumor suppressor genes usually have one of two functions…
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…1. Proteins that maintain the integrity of the genome by monitoring and/or repairing alterations in the genome 2. Proteins that are negative regulators or inhibitors of cell division
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Rb Gene
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Retinoblastoma tumor suppressor gene Cancerous tumor in retina of eye Negatively controls regulatory transcription factor (E2F) E2F activates genes required for cell cycle progression from G1 to S phase Binding of Rb protein to E2F inhibits its activity and prevents cell division When both copies of Rb are defective, the E2F protein is always active resulting in uncontrolled cell division
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Most cancers…
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…result from multiple defects in cell cycle regulation Develop only after several genes have been damaged
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The combined damage is enough to…
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…break cell cycle control Induce uncontrolled growth and metastasis
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Cancer is a series of changes…
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…cancer usually requires multiple genetic changes to same cell Begin with a benign genetic alteration that over time leads to malignancy Malignancy can continue to accumulate genetic changes that make it even more difficult to treat
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The defining characteristics of a malignant tumor include…
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…uncontrolled growth, ability of its cells to migrate and invade healthy tissue
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What is the relationship between B cell receptors and antibodies?
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An antibody is a secreted form of a B cell receptor
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Recombinant DNA
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DNA from 2 or more sources combined together using lab techniques
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GMO or GEO
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An organism whose genetic material has been altered using recombinant DNA technology
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Transformation
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Insertion of foreign DNA into a recipient host cell
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Gene Cloning
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Foreign genes inserted into bacteria are propagated as the bacteria multiply
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Why produce a GMO?
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Alter or eliminate a gene to study its function Want many copies of a gene to study Product lots of gene product Confer a novel trait on an organism Improve an existing trait or correct a defective gene
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Gene Therapy
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Introduction of a gene into affected cells Replace or augment defective copies with normal alleles Healthy allele must be sequenced and well understood DNA has to be introduced so that gene expression occurs (correct tissues, amounts, and at right time)
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Retroviruses
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Have RNA genome Have reverse transcriptase
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If human genes are packaged into a retrovirus..
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…virus is capable of inserting the human alleles Into a chromosome in a target cell
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Introducing a foreign gene into human cells…
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…1. Recombinant DNA prepared 2. Target cell infected 3. DNA produced 4. DNA inserted
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Severe Combined Immunodeficiency (SCID)
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Fatal genetic disease Sufferers have a very weakened immune system Caused by mutations in a gene on X chromosome Encodes a receptor protein needed for development of immune system T cells
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One approach to gene therapy…
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…1. Isolate stem cells 2. Infect with retrovirus carrying normal allele 3. Implant cells expressing normal allele into patient
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Most strategies for genetic engineering in agriculture focus on one of three objectives…
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…Reducing herbivore damage Making crops more resistant to herbicides Quality of food products
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Rice as a Target Crop
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Rice had no vitamin A Lack of vitamin A can cause blindness, susceptibility to disease B-carotene (precursor of vitamin A) Scientists want to developed rice enriched in B-carotene
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Synthesizing B-carotene in Rice
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3 enzymes Produce transgenic rice strains capable of producing B-carotene
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Ti plasmids transfer genes into host DNA…
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…1. Transfer of Ti genes 2. Transcription of Ti genes
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Agrobacterium Tumefaciens
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Bacterium that infects plants Produces a tumorlike growth called a gall Often used for genetic transformation of plants through transfer of its Ti plasmid
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To develop golden rice…
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…researchers modified Ti plasmids Contained the genes for the 3 enzymes needed to synthesize B-carotene Exposed plant embryos to Agrobacterium cells containing these genetically modified Ti plasmids
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A transgenic plan was produced…
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…now called golden rice High concentration of B-carotene gives it a yellow color
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Neuron Structure
Neuron Structure
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question

In what direction will the K+ ions move through the artificial channel?
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Out of the cell
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Does the K+ concentration gradient promote or impede the movement of K+ ions through the artificial channel?
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Promote
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Does the membrane potential promote or impede the movement of K+ ions through the artificial channel?
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Impede
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How does the movement of K+ ions through the artificial channel affect the membrane potential?
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Causes a hyperpolarization
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Mechanoreceptors that react to changes in pressure are part of the _____.
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Lateral line systems in fish
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Considering that sounds and odors both trigger changes in the patterns of action potentials from sensory cells, how does the brain perceive which sense is which when the action potentials reach the brain?
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The axons from different sensory neurons go to different areas of the brain
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Which of the following sensory receptors is correctly paired with its category?
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hair cell — mechanoreceptor
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Depolarization of hair cells in the mammalian ear results from increases in intracellular concentrations of what ion?
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Potassium
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_________________ allowing coelacanths to distinguish the blue wavelengths present in their deep sea habitat.
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Several blue opsins
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______________ allowing elephants to hear over long distances.
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Infrasound hearing
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____________ allowing bats to hunt by echolocation and moths to avoid bat predators.
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Ultrasonic hearing
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________________ allowing fruit eating mammals to distinguish ripe from unripe fruit.
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Red and yellow opsins
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Which of the following statements correctly describe(s) T tubules and their role in conducting action potentials in muscle cells? T tubules have receptor proteins that bind neurotransmitters released from the synaptic terminal of the motor neuron. T tubules lack the voltage-gated Na+ and K+ channels that are present in the plasma membrane. T tubules carry action potentials into the interior of the muscle cell via voltage-gated Na+ and K+ channels. T tubules are infoldings of the plasma membrane that encircle the myofibrils and are in contact with the sarcoplasmic reticulum. Without T tubules, the muscle cell would not be able to contract. T tubules are extensions of the sarcoplasmic reticulum that are in contact with the plasma membrane.
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T tubules carry action potentials into the interior of the muscle cell via voltage-gated Na+ and K+ channels. T tubules are infoldings of the plasma membrane that encircle the myofibrils and are in contact with the sarcoplasmic reticulum. Without T tubules, the muscle cell would not be able to contract.
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Which of the following statements correctly describe(s) the relationship between Ca2+ concentration in the cytosol and the response in the sarcomere? Increasing Ca2+ concentration causes troponin and tropomyosin to bind to actin. Increasing Ca2+ concentration causes movement of tropomyosin, exposing myosin-binding sites on actin. Decreasing Ca2+ concentration promotes interactions between actin and myosin. Decreasing Ca2+ concentration causes dissociation of Ca2+ from troponin. Increasing Ca2+ concentration causes troponin to bind to tropomyosin.
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Increasing Ca2+ concentration causes movement of tropomyosin, exposing myosin-binding sites on actin. Decreasing Ca2+ concentration causes dissociation of Ca2+ from troponin.
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Which of the following statements correctly describes why a series of closely spaced action potentials causes a sustained contraction rather than a series of closely spaced twitches?
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When a series of action potentials is closely spaced, there is not sufficient time for Ca2+ uptake into the sarcoplasmic reticulum between action potentials, and Ca2+ remains bound to troponin throughout the series.
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A person travelling to which of the following should be most concerned about contracting Zika?
answer

Caribbean
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You are a genetic engineer working to control Zika by altering the organism that transmits it. Which of the following are you working on?
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Mosquitos
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Assuming a recent discovery is shown to be true, which of the following appears to be true?
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Sexual transmission of Zika can occur from a man to a woman or from a woman to a man.
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If Zika follows recent trends of the top three sexually transmitted diseases in the United States, which of the following will happen?
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There will be an increase in the number of Zika cases resulting from sexual contact.
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Which of the following is currently a problem regarding Zika?
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It is unknown as to how long Zika can survive in semen.
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Which secretion is not a barrier that prevents pathogens from entering the body?
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Antigens.
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True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils.
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False
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How do cells involved in the innate immune response detect the presence of pathogens?
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Leukocytes recognize unique molecules on pathogens.
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Which of the following cells can engulf a pathogen?
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Macrophages.
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Which of the following statements best describes the role of mast cells in the inflammatory response?
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They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream.
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Which of the following events occurs first when a wound that breaks the skin has occurred?
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Platelets release proteins that form clots and decrease bleeding.
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The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors.
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True
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Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium?
answer

macrophage
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_____ interact with the antigen-class II MHC complex presented by macrophages.
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Helper T cells
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B cells that have been stimulated by interleukin-2 develop into _____.
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plasma cells
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The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response.
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perforin … cell-mediated
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Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____.
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B cells … plasma cells and memory cells
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Which of these cells is responsible for the rapidity of the secondary immune response?
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memory cells
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Which of these cells produce and secrete antibodies?
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plasma cells
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Checkpoint inhibitors work by utilizing which body system?
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immune
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Which of the following cancer patients is likely to fair the best after being treated with checkpoint inhibitors?
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A patient with a tumor that produces PD-L1.
question

Your friend has a genetic defect that prevents him from repairing DNA damaged during mitosis. What is this called?
answer

mismatch repair deficiency
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You are an oncologist. Six members of a family test positive for Lynch syndrome. Which of the following types of cancer are they most likely to get?
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colorectal
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You are a molecular pathologist and have been asked to look at the tumor from a lung cancer patient. Which of the following is most likely?
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There were more than fifty DNA mutations in the tumor.
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When cells were first taken from Henrietta Lacks, she was _____.
answer

suffering from cervical cancer
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How did doctors harvest and culture cells from Henrietta Lacks?
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Cells were taken while she was being treated for cancer many years ago, and these cells have been cultured in the lab ever since.
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Did doctors ask Henrietta Lacks’ permission to take her cells, and was she paid for them?
answer

She was never told that her cells were being taken, and neither she nor her family has been compensated.
question

What property of Henrietta Lacks’ cells was most unusual when they were grown in the laboratory?
answer

They continue to divide and multiply after decades of culture.
question

Cells taken from Henrietta Lacks have been used for experiments leading to _____.
answer

the development of a polio vaccine tests of the effects of atomic radiation on life new treatments for cancer
question

The success of cell therapy to treat cancer relies on which of the following?
answer

T cells
question

A patient with which of the following would be most likely to be successfully treated with CAR-T cell therapy?
answer

leukemia
question

Which of the following will have authorization to decide if and when CAR can be used?
answer

Food and Drug Administration
question

Your cousin has been added to a clinical trial for CAR. Which of the following will be a precursor to prepare him for this treatment?
answer

chemotherapy
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If CAR is approved, which of the following will be true?
answer

The treatment will be tailor-made for each patient.

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