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27 Cards in this Set
- Front
- Back
What is a primary or signal messanger?
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messanger that binds to extracellular receptors.
drugs, hormones, light, etc. |
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What is signal transduction?
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transfer of signal from outside of cell to inside of cell
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What is a cell surface receptor/G-protein coupled receptor(GPCR) or 7-Transmembrane receptor?
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Protein embedded in the cell membrane. The N-terminus has a binding site for signal messangers.
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What is a G protein?
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a heterotrimeric (alpha, beta, gama) complex that binds guanyl nucleotides.
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What is downstream effector activation? ex. adenylate cyclase
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an effector is a molecule that binds to a protein and activates the release of a second messanger
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What is a second messanger?
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molecule that transmits the signal inside the cell to tarter molecules in the cytosol/nucleus
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what is a kinase?
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enzyme that phosphorylates specific target molecules
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T or F . . . 7-TM receptors change conformation when signal binds
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T
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What do second messengers trigger?
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Protein phosphorylation
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what do protein kinases phosphorylate?
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inactive proteins inorder to activate them
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T/F . . . Kinases are involved in turning the signal off?
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T
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How is a signal turned off?
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1) dissociation of ligand from receptor
2) phosphorylation of the receptor |
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What does a G-Protein bind to when resting?
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GDP
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What happens to the G-protein when a ligand binds to a receptor?
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the G-protein changes conformation so that the GDP is released and a GTP binds.
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What happens to the alpha subunit once a G-protien changes conformation and releases the GDT and picks up a GTP?
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the alpha subunit dissociates from the beta/gama subunit and then the alpha subunit binds to adenylyl cyclase activating it to produce cAMP from ATP.
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List the steps of the Epinephrine signal transduction pathway.
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1) ephinephrine is released and binds to B-andrenergic receptors
2) binding stimulates G-prot. causing the G-prot conformation change which releases GDP and binds GTP. Alpha subunit then dissociates w/ the GTP to produce cAMP from ATP. 3) cAMP binds to protein kinase A which then activates phosphorylase kinase and gycogen phosphorylase which converts glycogen to glucose 6-phosphate into glucose 4) glucose is then transported outside of teh cell and into the bloodstream where it is used as a fuel by other cells to induce a "fight or flight" response. |
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how many molecules of glucose can be produced from 20 molecules of cAMP?
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10,000 molecules of glucose
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What terminates the epinephrine cascade?
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The G-protein(alpha) has intrinsic GTPase activity which hydrolyzes bound GTP to GDP and Pi.
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How long does the ATPase activity of the G-alpha take to terminate signaling?
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slow, seconds to minutes. This means Gprot can activate downstream components. After hydrolysis the GDP Alpha subunit reassociates with the G(beta/gama) subunits.
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List out the steps of the ANGIOTENSION signaling pathway.
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1) Angiotensin binds to the angiotensin receptor.
2) Stimulates G-protein 3) G(alpha) subunit activates phospholipase C which converts PIP2 to DAG and IP3 4) IP3 binds to and opens the Ca2+ channels on the endoplasmic reticulum --> Ca2+ is released. 4) Intracellular Ca2+ the binds to calmodulin which then binds to and activates PKC 4) PKC causes smooth muscle contractions and glycogen breakdown. 5) DAG actives PKC which phosphorylates other cellular proteins. |
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What does EGF stand for?
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Epidermal Growth Factor
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List out the steps of RAS activation.
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1) EGF binds to EGF receptor
2) cross phosphorylation occurs 3) phosphorylated Tyr is bound by Grb-2 4) Grb-2 binds SOS 5) SIS binds Ras 6) Ras activated and releases GDP and binds GTP 7) Ras binds Raf |
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What does Raf do?
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Raf acts as a protein kinase to change the activity of other proteins and control cell growth and differentiation
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List the three ways in which cancer chemotherapy can kill rapidly growing cells.
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1) antimetabolites
2) severely damaging DNA by alkylating agents 3) inhibiting receptor binding by use of anticytokines and antihormones |
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What is the relationship between ABL and BCR? What does gleevec do to solve this problem?
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ABL is a gene coding for a particular protien kinase. When this gene is inserted into the BCR gene it leads to defects in a growth signal cascade because it is not properly regulated and becomes over active.
gleevec trets myelogenous leukemia by inhibiting BCR-ABL kinase activity |
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How does cholera effect the body? Generally speaking and pathway wise.
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Invection by Vibrio cholerae which produces a toxin called choleragen that triggers massive secretion of electrolytes and fluids.
One B subunit of toxin binds to gut cell gangliosides and the other A subunit enters the cell. The A subunit selfstabilizes the Galpha protein in the GTP bound (ON) state. The A unit produces unending quantities of protein kinase A. This inturn opens a chloride ion channel and turns off the phosphorylation a Na/H exchanger. This leads to excessive loss of NaCl and water into the intestine. Loss of water and electrolytes follow. |
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What is Pertussis/whooping cough caused by. How does it work.
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Caused by infection by Bordetella pertussis.
Bordetella pertussis produces a toxin that modifies adenylyl cyclase, closes Ca2+ ion channels and opens K+ ion channels. The cyclase is jammed in the OFF position. Severe and debilitating cough reults. |