CELL COMMUNICATIONGeneral Principles of Cell SignalingFigure Q16-9Given the generic signaling pathway in Figure Q16-9, write the number corresponding to the item on the line next to the descriptor below.G-Protein-Coupled ReceptorsEnzyme-Coupled ReceptorsHow We Know: Untangling Cell Signaling PathwaysCHAPTER 16CELL COMMUNICATION 2009 Garland Science PublishingGeneral Principles of Cell Signaling16-1 Cell lines A and B both survive in tissue culture containing serum but do not proliferate. Factor F is known to stimulate proliferation in cell line A. Cell line A produces a receptor protein (R) that cell line B does not produce. To test the role of receptor R, you introduce this receptor protein into cell line B, using recombinant DNA techniques. You then test all of your various cell lines in the presence of serum for their response to factor F, with the results summarized in Table Q16–1.Table Q16-1Which of the following cannot be concluded from your results above?(a) Binding of Factor F to its receptor is required for proliferation of cell line A.(b) Receptor R binds to Factor F to induce cell proliferation in cell line A.(c) Cell line A expresses a receptor for Factor F.(d) Factor F is not required for proliferation in cell line B.16-2 For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once.Cells can signal to each other in various ways. A signal that must be relayed to the entire body is most efficiently sent by __________________ cells, which produce hormones that are carried throughout the body through the bloodstream. On the otherhand, __________________ methods of cell signaling do not require the release of a secreted molecule and are used for very localized signaling events. During __________________ signaling, the signal remains in the neighborhood of the secreting cell and thus acts as a local mediator on nearby cells. Finally, __________________ signaling converts electrical impulses into a chemical signal. Cells receive signals through a __________________, which can be an integral membrane proteinor can reside inside the cell.amplification G-protein phosphorylationcontact-dependent K+ channel receptorendocrine neuronal targetepithelial paracrine16-3 Rank the following types of cell signaling from 1 to 4, with 1 representing the type of signaling in which the signal molecule travels the least distance and 4 the type of signaling in which the signal molecule travels the largest distance.______ paracrine signaling______ contact-dependent signaling______ neuronal signaling______ endocrine signaling16-4 Explain why the signal molecules used in neuronal signaling work at a longer range than those used in contact-dependent signaling.16-5 Circle the phrase in each pair that is likely to occur more rapidly in response to an extracellular signal.A. changes in cell secretion / increased cell divisionB. changes in protein phosphorylation / changes in proteins being synthesizedC. changes in mRNA levels / changes in membrane potential16-6 Receipt of extracellular signals can change cell behavior quickly (e.g., in seconds or less) or much more slowly (e.g., in hours).A. What kind of molecular changes could cause quick changes in cell behaviour?B. What kind of molecular changes could cause slow changes in cell behaviour?C. Explain why the response you named in A results in a quick change, whereas the response you named in B results in a slow change.16-7 Which of the following statements is false?(a) Nucleotides and amino acids can act as extracellular signal molecules.(b) Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription.(c) Some signal molecules are transmembrane proteins.(d) Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.16-8 All members of the steroid hormone receptor family __________________.(a) are cell-surface receptors(b) do not undergo conformational changes(c) are found only in the cytoplasm(d) interact with signal molecules that diffuse through the plasma membrane16-9Figure Q16-9Given the generic signaling pathway in Figure Q16-9, write the number corresponding to the item on the line next to the descriptor below._________ receptor protein_________ effector proteins_________ intracellular signaling proteins_________ ligand16-10 The lab you work in has discovered a previously unidentified extracellular signal molecule called QGF, a 75,000-dalton protein. You add purified QGF to different types of cells to determine its effect on these cells. When you add QGF to heart muscle cells, you observe an increase in cell contraction. When you add it to fibroblasts, they undergo cell division. When you add it to nerve cells, they die. When you add it to glial cells, you do not see any effect on cell division or survival. Given these observations, which of the following statements is most likely to be true?(a) Because it acts on so many diverse cell types, QGF probably diffuses across the plasma membrane into the cytoplasm of these cells.(b) Glial cells do not have a receptor for QGF.(c) QGF activates different intracellular signaling pathways in heart muscles, fibroblasts, and nerve cells to produce the different responses observed.(d) Heart muscle cells, fibroblasts, and nerve cells must all have the same receptor for GQF.16-11 Can signaling via a steroid hormone receptor lead to amplification of the original signal? If so, how?16-12 Acetylcholine is a signaling molecule that elicits responses from heart muscle cells, salivary gland cells, and skeletal muscle cells. Which of the following statements is false?(a) Heart muscle cells decrease their rate and force of contraction when they receive acetylcholine, whereas skeletal muscle cells contract.(b) Heart muscle cells, salivary gland cells, and skeletal muscle cells all express an acetylcholine receptor that belongs to the transmitter-gated ion channel family.(c) Active acetylcholine receptors on salivary gland cells and heart muscle cells activate different intracellular signaling pathways.(d) Heart muscle cells, salivary gland cells, and skeletal muscle cells all respond to acetylcholine within minutes of receiving the signal.16-13 When the neurotransmitter acetylcholine is applied to skeletal muscle cells, it