Phys chap 5

Cellular proteins that are the targets for signaling molecules are called ____
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Cellular proteins that are the targets for signaling molecules are called ____
Receptors
Receptors which bind intercellular chemical messengers are found in three main locations; in the cell's plasma membrane or inside the cell, either in the
Cytosol or the nucleus
With regard to intercellular signaling, which of these statements is true about the concept of specificity
Cells respond only to certain chemical messengers because they have receptors that bind those messengers
Down-regulation has the effect of reducing the target cells' responsiveness to frequent or intense stimulation by a messenger - that is, ____ them and thus represents a local negative feedback mechanism
Desensitizing
The change in shape of receptor caused by binding of a chemical messenger is called receptor activation
True
Most inactive receptors for lipid-soluble messengers are located in the cell
Nucleus
A cell will only respond to those signals for which it has
Receptors
Water-soluble messengers bind to four classes receptors on the plasma membrane: 1) receptors that are also ____-gated ion channels; 2) receptors that are also ____; 3) receptors that activate a cytosolic Janus ____ associated with them; 4) receptors that interact with an associated plasma membrane ____ protein
Ligand; enzymes; kinase; G
The main cellular location of receptors for hydrophobic messengers like steroid hormones is
In the nucleus
What part of a cell do water-soluble messengers bind to
extracellular portion of protein receptors
Which three of the following are water-soluble messengers that bind to extracellular receptors on cellsAutocrine compounds, neurotransmitters, protein hormonesSubstances that are generated in the cytoplasm when extracellular chemical messengers bind to membrane receptors are known asSecond messengersWhich one of the following signal transduction mechanisms is least likely to be part of signaling pathway of water-soluble chemical messengersDirect binding of messenger to nuclear receptors that alter transcriptionExamples of plasma membrane receptors for water-soluble messengers are proteins that act as ligand-gated channels. These are typically used for the transfer ofIonsThe extracellular messengers (such as hormones or neurotransmitters) that reach a cell and bind to its specific plasma membrane receptors are often referred to asFirst messengersWhich two are most common results of the binding of first messengers to a ligand-gated channelIon diffusion and a change in electrical charge across membrane Entry of Ca2+, which can act as a second messenger inside the cellProtein kinasesAre enzymes that phosphorylate other proteins by transferring a phosphate group to them from ATPA signal-transduction pathway that involves the binding of a neurotransmitter to a ____-____ ion channel may be involved in changes in membrane potential due to movement of ions across the membraneLigand-gatedThe largest class of membrane-protein receptors has a three-subunit protein complex attached to the cytosolic surface of the inactive receptors; these receptors are known asG-protein couple receptorsA rapid change in electrical potential of the plasma membrane most directly results from the binding of a first messenger molecule toLigand-gated ion channelsPhospholipase C catalyzes the breakdown ofPIP2An enzyme that changes another protein's three-dimensional conformation to alter the protein's activity by transferring a phosphate group to them from ATP is called aProtein kinaseCalmodulinIs an intracellular Ca2+ binding protein which, when bound to Ca2+, alters its conformation and activates or inhibits a large variety of enzymes and other proteinsThe largest number of membrane receptors are in a category in which the inactive receptor is bound to a 3-part protein complex located on the cytosolic surface of the plasma membrane; this protein complex belongs to a family of proteins known asG proteinsMembers of the Eicosanoid familyCyclic endoperoxides, prostaglandins, thrombocytes, leukotrienesActivated _________ _________ catalyzes the conversion of cytosolic ATP into cyclic AMP (cAMP), which then allows cyclic AMP to act as a _______ messenger.Adenylyl cyclase; secondOrder of Gq pathwayGq is activated by a receptor Gq activates the phospholipase C Phospholipase C catalyzes the breakdown of PIP2 PIP2 is broken down into DAG and IP3With regard to cellular second messenger systems, which best describes the concept of "cross talk"Activated molecules from one second messenger system can alter the activity of receptors and signaling molecules generated by other pathwaysCalcium ions frequently act as ____ messengers within cellsSecondaryA common signaling pathway by which an increase in cytosolic Ca2+ concentration induces cell responses involves Ca2+ binding to ________ , which changes its shape and allows it to activate or inhibit a large variety of enzymes and other proteins.CalmodulinA G protein activates plasma membrane adenylyl cyclase, which catalyzes the formation of the second messenger ____ from ATPcAMP