Practice_exam_III_Answers

Practice_exam_III_Answers - Practice exam III 1 In signal...

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Practice exam III 1. In signal transduction pathways for hydrophilic ligands a key function occurring at the plasma membrane is: a. To allow the ligand to pass across the membrane. b. To have a protein receptor specifically bind the ligand. c. To stop the signal transduction from occurring across the membrane into the cytoplasm. d. To prevent the membrane receptor from moving laterally in the phospholipids layer. 2. Find the correct match of ligand and molecule: a. Nitric oxide : small peptide. b. acetylcholine : polypeptide. c. gibberelic acid : gas. d. epinephrine : small amine. 3. Which of the following are not used in cell signaling as a ligand, or part of the signal transduction pathway? a. Gap junctions. b. Plasmodesmata. c. Cell adhesion proteins. d. Polysaccharides. e. Kinase proteins. 4. A G-protein linked receptor system has this characteristic: a. The ligand passes through the plasma membrane to an intracellular receptor. b. The G-protein linked receptor itself has serine-threonine kinase activity. c. The G-protein is active when GTP is bound but inactive when GDP is bound. d. The G-protein when activated at the plasma membrane then goes directly into the nucleus. 5. The tyrosine kinase receptor system has this characteristic: a. The receptor becomes an active tyrosine kinase when it binds the ligand and forms a dimer. b. The kinase is located on the ER membrane surface. c. Polypeptide growth hormones are not used as ligands for the tyrosine kinase receptor system. d. Transduced signals in the cytoplasm for the tyrosine kinase receptor system always require changes in the calcium concentration in the cytoplasm. 6. The intracellular receptor system has this characteristic: a. It is used for signal transduction of neurotransmitters. b. It uses gated ion channels within the cytoplasm. c. It is only found in female mammals. d. Its receptor bound to the ligand becomes a transcription factor. 7. A reason that there are a series of enzyme steps such as protein kinase cascades in eukaryotic signal transduction pathways is: a. Kinases generally are very inefficient enzymes and so many enzymes steps are needed to get enough signal transduced in the cytoplasm. b. The enzyme series can amplify the effect of the signal received at the cell surface. c. There are many separate steps because the cell wants to slow down the transduction of the signal in the cytoplasm.
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d. Eukaryotic cells always require more enzymes in biochemical reaction pathways than do prokaryotic cells. 8. Which of the following is NOT a second messenger molecule: a. Cyclic AMP. b. Inositol triphosphate. c. Calcium. d. Estrogen. 9. Interphase includes the time or period of: a. S phase. b. Anaphase. c.
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This note was uploaded on 10/18/2011 for the course BMB 401 taught by Professor Kaguni during the Fall '08 term at Michigan State University.

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Practice_exam_III_Answers - Practice exam III 1 In signal...

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