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66 Cards in this Set
- Front
- Back
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tight junctions
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type of cell junction
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tight junctions
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belts around epithelial cells lining organs
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tight junctions
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prevent leakage in/out of the organ
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tight junctions help prevent leakage with
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urinary bladder and intestinal epithelium
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Desmosomes are "rivets" that
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hold one cell to another
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Desmosomes are found where?
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in tissues w/ high mechanical stress
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One place Desmosomes are found in the human body---
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skin and neck of uterus
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Gap Junctions
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type of cell junction
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gap junctions permit passage of material from
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cytoplasm of one cell to another
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Ion flow coordinating cardiac muscle contraction in muscle tissue of the heart is a type of
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gap junction
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Plasmodesmata
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connects 1 plant cell to another
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Plasmodesmata in plant cells is analogous to _____ in animal cells?
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gap junctions
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Definition of signal-transduction pathway
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signal on a cell's surface is converted into a specific cellular response
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Paracrine and Synaptic are examples of
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Local signaling ( short distance signaling)
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Paracrine are
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growth factors
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Synaptic are
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neurotransmitters
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long distance signals are
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hormones
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Sutherland discovered the _____ in 1971
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stages of cell signaling
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Glycogen depolymerization is done by
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epinephrine
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there are how many steps to glycogen depolymerization?
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3
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1st- Reception which ___
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detects target cell
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2nd- Transduction which____
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is a single step or series of changes
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3rd- Response which____
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triggers a specific cellular response
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signal ____ & Initiation of _____
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reception & transduction
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signal molecules behave like a
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ligand
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ligand
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small molecule that specifically bonds to a larger molecule
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signal reception and initiation of Transduction
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causes receptor protein to undergo conformational (shape) change
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3 major types of receptors
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G-protein-linked receptors, Tyrosine-kinase, and Ion-channel
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G-protein-linked receptors are
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plasma membrane receptors
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G-protein-linked receptors work with a protein called a
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"G-protein"
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loosely attached to cytoplasmic side of membrane
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G-proteins
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G-proteins function as a
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switch
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when G-protein is an on switch
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GTP is bound to it
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When G-protein is an off switch
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GDP is bound to it
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first step of G-protein links
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receptor protein is activated, binding an inactive G-protein to it
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second step of G-protein links
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GTP displaces GDP, activating the G-protein
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3rd step of G-protein links
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G-protein binds to another protein (usually enzyme)
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4th step of G-protein links
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triggers cell response
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G-protein systems are ____ and _____
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widespread & diverse
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G-protein systems control
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embryonic development, vision, and smell
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the similarity of g-protein structure in modern organisms suggest
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the system evolved early
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G-proteins are possibly
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sensory receptors of ancient microbes
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G-proteins are involved in human
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diseases
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cholera, pertussis, botulism, toxins
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interfere with G-protein function
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60% of all medicines influence
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G-protein pathways
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Tyrosine-Kinase Receptors are
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membrane receptors that attach phosphates to protein tyrosines
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tyrosines are proteins with
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the AA tyrosine in them
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T-K receptors act as
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both a receptor and a enzyme
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Ligand binding in T-K receptors causes
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2 receptors to clump together, forming a dimer
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T-K receptors activate the tyrosine parts and
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they add phosphates to each other. now T-K receptors are fully activated and recognized by relay proteins
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One dimer ( the result of ligand binding in T-K receptors) can activate
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10 or more different relay proteins simultaneously
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T-K receptors trigger many different
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transduction pathways and responses which is the key difference between T-K receptors and G-protein receptors
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Ligand-Gated Ion Channels open and close
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protein pores in Cell Membrane
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Ligand-Gated Ion Channels allow or block
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flow of ions (Na+ or CA2+
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Ligand-Gated Ion Channels often directly
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affect cell function. Example: synapse between Nerve Cells- L-G Ion Channels trigger electrical signal which propagates along nerve cell
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Protein Phosphorylation is a common mode of _____ and major mechanism of ____
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regulation , signal transduction
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protein activity regulation adds phosphate from ATP to
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a protein which activates more proteins
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protein activity regulation is controlled by enzymes which =
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protein kinases (1% of all our genes code for these) Example: Cell reproduction
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Protein Activity regulation: reversal enzyme=
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protein phosphatases- removes phosphates from proteins
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Protein activity regulation: protein activity depends on
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balance between kinases and phosphatases in cell
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Secondary messengers are a _____ pathway
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non-protein signaling
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example of secondary messenger:
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Cyclic AMP (cAMP); Ca++
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Example of secondary messenger non-protein signaling pathway-
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Glycogen breakdown with epinephrine. Enzyme: adenylyl cyclase converts ATP to cAMP
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secondary messengers are
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G-protein-linked receptor
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Cellular responses to signals:
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cytoplasmic activity regulation.
cell metabolism regulation. nuclear transcription regulation. |
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Termination of signal:
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signal response is terminated quickly by the reversal of ligand binding (aka. the removal of the ligand)
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