Concept explainers
Effect of BPA on Insulin Secretion Bisphenol A (BPA) is an endocrine disruptor that may increase the risk of type 2 diabetes. Angel Nadal suspected that BPA disrupts insulin
FIGURE 34.11 Effects of BPA and DPN on glucose-stimulated insulin secretion. DPN is a chemical known to bind and activate estrogen receptors on pancreatic cells. A glucose concentration of 8 millimolar (mM) is equivalent to that of the blood after a meal.
How were the effects or DPN and BPA similar? How did they differ?
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Chapter 34 Solutions
Biology: The Unity and Diversity of Life (MindTap Course List)
- Based on your understanding of the binding of insulin, select all of the following events that you would expect to occur in muscle cells due to insulin binding to receptors.Group of answer choices a. Glycogen synthesis is activated b. PFK is stabilized in the R-state and glycolysis is activated c. GLUT4 (transporters) are increased in concentration at the plasma membrane d. Fructose 2,6-bisphosphate increased levels aid in stabilization of the T-state fructose 1,6-bisphosphatase e. Gluconeogenesis is activated in response to elevated fructose 2,6-bisphosphate levels f. Phosphorylation cascades allow for covalent modifications that would aid in the breakdown of glycogen to allow for increased levels of glucose 6-phosphate in the cell g. Hexokinase is inhibited so glucose will not be brought into the cell in high amounts h. Glycogen breakdown pathway is inactivatedarrow_forwardA certain type of tumor results in the overproduction of glucagon. Researchers claim that treatment with insulin can counteract the effects of the excess glucagon on the pathway shown in Figure 2. Provide reasoning to justify the researchers' claim.arrow_forwardDescribe the process that results in the activation of multiple copies of PKBPKB in response to the binding of a single molecule of insulin to its receptor. Explain why insulin can stimulate the activation PKBPKBof but not the activation of PKPK.arrow_forward
- Describe two features of insulin signaling that affect glucose utilization. Aβ-adrenergic response can be modulated through the actions of a receptorkinase and arrestin because phosphorylation by the kinase desensitizes thereceptor. How might signaling by a tyrosine receptor kinase, such as theinsulin receptor, be modulated?arrow_forwardEpinephrine stimulates glycogen breakdown by activating glycogen phosphorylase. However, in the research lab, no glycogen breakdown occurred when epinephrine was added to a test tube containing the enzyme and its substrate, glycogen. Explain why glycogen phosphorylase could be activated by epinephrine only when the hormone was added to intact cells in a solution.arrow_forwardIn the liver and muscle cells, epinephrine stimulates the release of glucose from glycogen by inhibiting glycogen synthesis and stimulating glycogen breakdown. Outline the signaling events that occur after epinephrine binds to its receptor and the resultant increase in the concentration of intracellular cAMP and release of glucose.arrow_forward
- Diabetes often results in the production of reduced levels of insulin. Researchers claim that a drug that binds to and blocks the active site of GSK3 might mimic the role of insulin in the pathway shown in Figure 2. Provide reasoning to justify the researchers' claim.arrow_forward. Which observation suggested to Sutherland the involvementof a second messenger in epinephrine’s effect on liver cells?(A) Enzymatic activity was proportional to the amount ofcalcium added to a cell-free extract.(B) Receptor studies indicated that epinephrine was a ligand.(C) Glycogen breakdown was observed only when epinephrinewas administered to intact cells.(D) Glycogen breakdown was observed only when epinephrineand glycogen phosphorylase were mixed.arrow_forwardHuman growth hormone binds to a cell-surface membrane protein that is not a receptor tyrosine kinase. The intracellular domain of the receptor can bind other proteins inside the cell. Furthermore, studies indicate that the receptor is monomeric in the absence of hormone but dimerizes on hormone binding. Propose a possible mechanism for growth-hormone signaling.arrow_forward
- Name two proteins that are effectors of the insulin signaling pathway in adipocytes, liver, or muscle cells. Explain how these effector proteins address the conditions that triggered insulin release.arrow_forwardin the insulin signaling pathway, the function of the PIP3-dependent Protein Kinase-1 is to add a __ group to the enzyme __ , which activates that enzyme.arrow_forwardSeveral hormones may activate the same G protein. Therefore,different hormones may have the same effect. For example,glycogen degradation is initiated by both epinephrine and glucagon. Why is overlap of function an advantage?arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning