Chapter 11 Study Guide Answers – Flashcards
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What is a signal transduction pathway?
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Process by which a signal on a cell's surface is converted to a specific cellular response in a series of steps. How does a yeast mating serve as an example of a signal transduction pathway?,Alpha yeast sends alpha signals that A yeast receives. A yeast sends A signals that only alpha can receive. The respective signals are then transduced and a response is carried out (mating).
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Paracrine signaling
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Secreting cells sends regulators to target cells and to all cells in the vicinity. Examples are animal cells and growth hormones.
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Synaptic signaling
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Electrical signals trigger chemical signal. Very specific affects only target cell. Examples are neurotransmitters.
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How does a hormone qualify as a long-distance signaling example?
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Hormones can travel to any part of the body via the circulatory system.
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Reception
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Detection of signaling molecule
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Transduction
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Signal converted to form that can bring about a specific cellular response.
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Response
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transduced signal triggers some sort of cellular response.
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Ligand
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Molecule that specifically binds to another, usually bigger molecule.
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What activates a G protein?
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1 Signaling protein activates receptor 2 receptor changes shape 3 G protein binds to enzyme.
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A G protein is also a GTPase enzyme. Why is this important?
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It stops the signal and converts GTP back to GDP
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What does a kinase enzyme do?
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Catalyzes transfer of phosphate groups.
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How does tyrosine kinase function in the membrane receptor?
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It allows for the activation of many signal transduction pathways.
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What is a key difference between receptor kinases and G protein-coupled receptors?
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Receptor kinases can activate a lot more signal transduction pathways than just the one that G protein-coupled receptors can.
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Each activated protein in tyrosine kinase triggers a signal ______ pathway leading to a ______ response.
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Transduction/cellular In what body system are ligand-gated ion channels and voltage-gated ion channels of particular importance?,Nervous system
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Intracellular receptors are found in the ______ or ______ of the cell
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where they bond to chemical messengers that are _____ or very small, like nitric acid.,Cytoplasm/nucleus/hydrophobic
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What are transcription factors?
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They are molecule complexes that control which genes are turned on and transcribed to mRNA
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What are two benefits of multistep pathways?
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Amplification of signal, and better regulation.
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What is the role of protein kinase?
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Transfer phosphate groups from ATP to proteins
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What is the role of protein phosphatases?
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Remove phosphate groups from proteins.
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What is the difference between a first messenger and a second messenger?
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First messenger is the ligand, second messenger is any small, non-protein components of a signal transduction pathway.
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Explain the mechanism of disease in cholera.
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G protein cannot hydrolyze GTP to GDP 1 enzyme that the G protein activates is always on 2 cAMP constantly is being produced 3 salt is constantly released as a cellular response 4 due to osmosis, diarrhea.
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List three pathways often induced by calcium ions.
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Pathway via mitochondria, ER, and plasma membrane.
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What happens to the cytoplasmic concentration of calcium when it is used as a second messenger?
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It increases.
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When cell signaling causes a response in the nucleus
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what normally happens?,Proteins become transcription factors, certain genes are chosen, these are then transcribed.
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When cell signaling causes a response in the cytoplasm
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what normally happens?,Regulation of activity of proteins.
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How do scaffolding proteins enhance a cellular response?
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Enhancement of speed and accuracy because the rate of response is no longer limited by rate of diffusion.
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What specifically happens to a cell during the process of apoptosis?
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DNA chopped up, cell shrinks, lobes up, vesicles form, digestion by scavenger cells.
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Give one example of signal for apoptosis coming from outside the cell
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and two from inside the cell.,Out: death signaling molecule reactions with protein and activates Ced-9. IN1: Leaking form mitochondria. IN2: ER due to excessive missfolding of proteins.
