BS 161 EXAM 4 STUDY QUESTIONS WITH ANSWERS (LATEST EDITION)

BS 161 EXAM 4 STUDY QUESTIONS WITH ANSWERS (LATEST EDITION) 1. How can phosphorylation affect protein function? Select ALL choices that apply A.It can activate some enzymes. B.It can inhibit some enzymes. C.It can provide a site or location on some proteins for other proteins to bind. D.It acts as a coactivator for some proteins. E.It serves as a ligand to activate some receptor - ANSWER A.It can activate some enzymes. B.It can inhibit some enzymes. C.It can provide a site or location on some proteins for other proteins to bind. 2. Norepinephrine is a hormone that is released into the blood when the adrenal gland is stimulated. What type of signaling does this represent? A.Endocrine B.Paracrine C.Synaptic D.Direct contact - ANSWER A. Endocrine 3. The EGF-receptor is a receptor tyrosine kinase that binds to epidermal growth factor (EGF) and upon ligand binding stimulates a signaling pathway that involves Ras, which ultimately promotes cell division. If an inhibitor that inhibited all G proteins was added to cells, how would this affect the ability of these cells to respond to EGF? A.The inhibitor would have no effect, because the EGF-receptor is not a G protein-coupled receptor. B.While the receptor would dimerize and autophosphorylate in the presence of the inhibitor, downstream signaling would be prevented because the inhibitor would affect Ras activity. C.In the presence of the inhibitor, the receptor could bind to EGF and dimerize, but it would not be able to autophosphorylate because this requires the activity of a G protein. - ANSWER B. While the receptor would dimerize and autophosphorylate in the presence of the inhibitor, downstream signaling would be prevented because the inhibitor would affect Ras activity. 4. Release of acetylcholine from a neuron-to a muscle cell triggers contraction to a heart muscle cell slows the rate of contraction-to a pancreatic cell triggers the release of digestive enzymes. How can acetylcholine have different effects on different cells? A. Acetylcholine binds to intracellular receptors in some cell types, tyrosine kinase receptors in other cell types, and G protein-coupled receptors in other cells types, which will lead to varied responses. B. Acetylcholine is modified differently in each cell it enters, thus triggering a different response in different cell types. C. Different subtypes of the acetylcholine receptor activate different signal transduction pathways in different cells. - ANSWER C. Different subtypes of the acetylcholine receptor activate different signal transduction pathways in different cells. 5. Axl is a receptor tyrosine kinase that, when ligand binds, stimulates several pathways including the MAP kinase signaling pathway, leading to cell division. You take a cell line and treat it with a ligand that stimulates the Axl-MAP kinase pathway and measure the rate of cell division. You take a second sample of the same cell line, and in addition to adding the ligand, you treat it with a GTPase inhibitor. What do you expect to see with the addition of the GTPase inhibitor? A. The rate of cell division will increase, because Ras will not be inactivated. B. The rate of cell division will decrease, because Ras will not be activated. C. The rate of cell division will decrease, because the ligand cannot bind to Axl. D .The rate of cell division will increase, because more GDP can be exchanged onto Ras - ANSWER A. The rate of cell division will increase, because Ras will not be inactivated. 6. Histone - DNA InteractionsHistones are proteins that help compact DNA. The side chain from which amino acid pictured here is likely to interact favorably with the backbone of DNA? - ANSWER A side chain with a positive charge because the phosphate backbone carries a negative charge. 7. Terminology and RepresentationsWhat structure(s) is/are indicated by the numeral 2? A. unreplicated chromosome B. sister chromatids C. centromere - ANSWER C. Centromere -- the thing holding the two chromatid together (holds together two blue lines) 8. f. Explain the possible significance of telomerase in germ cells and cancerous cell - ANSWER Telomerase is the like the buffer of DNA when it copies and allows for no damage to be done to the information on the strand. For example, a young child has a lot more telomerase than a 50 year old. If cancerous or germ cells have a lot of telomerase they can continue to multiply and not be damaged or die off. It would be like a cat you didn't want having nine lives so you're stuck with it.