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| a compound produced in one cell, and used to transmit a messae to one (or many) other cells |
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| a specifit protein that is the site for binding of a signalling molecule |
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| the mechanism that is activated by a receptor |
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| a small intracellular signalling molecule. The extracellular signals are the "first messengers". |
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| a compound that binds to a receptor |
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binds to the receptor and activated effector.
Full- maximum response
Partial- only partially activates the effector |
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Definition
| binds to the receptor and does not activate effector. Prevents agonists from binding to receptor. |
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| binds to receptor and inactivates effector (opp. response of agonist) |
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| competes with an agonist for some binding site on a receptor. Creates a rightward shift of curve on dose response cure. Decreases potentcy. Increase [agonist] to get the same effect. |
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| Noncompetitive Antagonist |
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Definition
| binds to a receptor at a discrete site and changes the maximal response with out altering the "EC50". Maximum response of the drug changes. |
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| Contact-dependent Signaling |
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Definition
| signaling molecule is not diffusible. Cells must be in direct contact. Important during development of some types of immune f(x). |
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Definition
| signaling molecules are released into the extracellular space, but are rapidly taken up by other cells or destroyed by enzymes. Thus, paracrine signals effect on cells in the local vicinity of the signaling cell. Specifically determined by which cells have the receptors for signalling molecule. |
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Definition
| allows very specific and very rapid delivery of highly concentrated signaling molecules at large distances from the cell soma. The primary signaling molecules released from the synaptic terminals are called neurotransmitters. |
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| allows relatively slow and non-specific delivery at low concentrations via the bloodstream. The signaling molecules released from endocrine cells are hormones. Signaling molecules in all these systems bind to receptors. |
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Definition
Endocrine=high affinity
Synaptic= lower affinity |
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| Cystolic/Nuclear Receptors |
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Definition
| hormones, nonpolar, lipid soluble molecules (can cross cell membrane; ligand activated gene regulatory proteins |
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| water soluble but not membrane permeant |
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| Ligand Gated Ion Channels (Ionotropic Receptors) |
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Definition
| When open create a pore. Pore is either selective for ions or non-selective. Flow through pore determined by electrochemical gradient. PENTAMERS-Some subunits are structural (3 per channel) and others are ligand binding (2 per channel). |
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| Variation of Ligand Gated Ion Channels |
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Definition
| More than only 5 types of subunits. Multiple combinations of subunits. Multiple versions of each subunit also exist. |
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Definition
| Nicotinic acetylcholine receptors inthe CNS |
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Definition
| binds to nicotinic Ach receptors at the neuromuscular j(x) and can induce paralysis |
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| Barbituates and Tranquilizers |
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Definition
| bind to GABA receptors and potentiate their f(x) by increasing sensitivity of the receptor to GABA |
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Definition
| lover bp, relieve chest pain, correct irregular heart beats, and prevent migraines |
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| serotonin reuptake inhibitor; works indirectly by blocking Na+ driven active transport mechanisms. ie Prozac |
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Definition
| binds to a site on the subunit different from the binding site of the ligand to modulate f(x) |
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| G-protein linked receptors |
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Definition
| largest family of cell-surface receptors. 1/2 known drugs work through G-protein mechanism. Long polypeptide chains that have 7 transmembrane spanning regions. |
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| G-protein receptor activated by Ach |
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| 3 characteristics all G-protein receptors have in common |
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Definition
1. extracellular binding site
2. 7 transmembrane folds
3. area on cytosol that reacts with a G-protein |
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Definition
| 3 proteins; alpha, beta, and gamma |
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| regulator of G-protein signaling; act as alpha subunit specific GTPase activating proteins |
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| 3 Main effectors targeted by G-proteins |
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Definition
1. Adenylyl Cyclase
2. Phospholipase
3. Membrane bound ion channels |
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Definition
| membrane bound enzyme that synthesizes cAMP from ATP |
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Definition
| Cyclic AMP activates the cyclic AMP dependent proteing kinase (PKA) |
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| cAMP dependent protein kinase; activates the transfer of the terminal phosphate from ATP to specific serine or theronine residues on the target proteins, thereby regulating their f(x). Phosphorylate inactive CREBS to active. |
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Definition
| acticates adenylyl cyclase, and increses [cAMP] |
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Definition
| inhibits adenylyl cyclase (although beta-gamma subunit can also interact with ion channels) |
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Definition
membrane bound enzyme activated by the G-protein Gq. Breaks down phosphatidylinositol 4,5-biphosphate into two active signaling molecules:
IP3 and DAG |
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Definition
| enters the cytosol to bind to IP3 receptors on smooth ER to release stored Ca2+ |
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Definition
| diacylglyceral; stays associated with the membrane; activates kinase C which is Calcium dependent. |
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Definition
| activated by a muscarinic Ach receptor; alpha subunit inhibits adenylyl cylase, Beta-gamma complex interacts directly with K+ channels in the cardiac plasma membrane and opening them. |
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Definition
| G-protein is activated by high light levels to catalyze the breakdown of cGMP which closes Na+ channels which lowers trasmitter release in the Rods of the eye. |
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Definition
| transmembrane proteins with only 1 transmembrane domain |
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| 6 major classes of enzyme linked receptors |
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Definition
| typrosine kinases, tyrosine phosphatases, serine/threonine kinase, or guanylyl cylclases |
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Definition
| favors uncharged polar molecules, no membrane bound proteins,driven by an electrochemical gradient |
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| Facilitated Diffusion (Passive Transport) |
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Definition
| requires membrane bound protein, dependent on electrochemical gradient |
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Definition
| requires a source of energy to work against the electrochemical gradient |
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| transports two solutes in the same direction |
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Definition
| transports two solutes in opposite directions |
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| Secondary Active Transport Mechanism |
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Definition
| uses energy stored in the electrochemical gradient of Na+ to transport glucose; net flux of both is inward due to cooperative binding |
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| 3 Na+ out of cell for every 2K+ in;functions to create Na+ gradient for secondary transport, membrane potential, maintain osmotic balance. |
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Definition
| the concentration of osmotically active particles in solution, often expresses as osmoles/L |
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| Osmotically Active Particles |
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Definition
| particles that interact withe water but are not impermeable to the plasma membrane; ie ions in solution |
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Definition
| the amount of a substance that dissolves in solution to form 1 mole of osmotically active particles |
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| high solute concentration and thus low water concentration-->crenated cells |
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Definition
| low solute concentration and thus high water concentration-->lysed cells |
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Definition
| one that is osmotically balance (has smae solute concentration) as on the other side of the membrane; want in biology |
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| Normal Osmolarity for blood |
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Definition
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Definition
| a process by which cells engulf material from their surroundings |
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Definition
| a mechanism for secretion of intracellular substances into the extracellular space |
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| Endocytosis and Exocytosis |
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Definition
| move inside and outside of the cell without transversing the lipid bilayer |
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Definition
| "cell eating"; engulf large particles or entire microorganisms for subsequent breakdown and recycling |
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| breaks away from the cell membrane to fuse with a lysosome |
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Definition
| inestions of small particles in solution; "cell drinking"; ie ingestion of LDL to use in making new membranes |
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| Constitutive Secretory Pathway |
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Definition
| vesicular proteins are needed for vesicle to fuse with the membrane and undergo exocytosis |
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| Regulated Secretory Pathway |
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Definition
| vesicle will not release contents to outside of the cell until an external signal is received |
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| regulated secretory pathway |
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Definition
| a differentiated structure within a cell that performs a specific function |
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Definition
| Contains all the genetic material of the cell; chromosomes make up genetic material; transcription and mRNA synthesis takes place here; has an inner and outer membrane |
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| forms spool like structures on which the DNA is wound |
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| site of protein synthesis |
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| specialized subnuclear structure where ribosomes are constructed |
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| the process of using mRNA to synthesize a protein |
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Definition
| a seqence of three nucleotides in the mRNA. (Codon) |
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Definition
| synthesize enzymes that facilitate reactions within the cytosol |
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| Bound Ribosomes (rough ER) |
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Definition
| synthesize membrane bound, lysosomal, and secretory proteins |
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Definition
| principle site of lipid, lipoprotein, and steroid hormone synthesis. Also, regulates the intracellular calcium concentration |
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| modifies carbohydrate groups on some proteins; packages other proteins for vesicular secretion; produces polysaccharides and attaches them to proteins to form glycolipids |
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| intracellular digestion; works only at acidic pHs so that it won't degrade the cell if it lyses |
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Definition
| primary site of ATP production; bounded by a double membrane; outer membrane is smooth |
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| folds of inner membrane of mitochondria |
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| mitochondrial DNA; inherited maternally |
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