Concept explainers
Abnormal triglyceride accumulation in the liver (hepatic steatosis) leads to insulin resistance, which is trademark trigger of type 2 diabetes. Insulin-resistant hepatocytes perform gluconeogenesis even in the presence of high blood glucose levels, which exacerbates the hyperglycemia. These insulin-resistant cells also perform excessive b-oxidation, which can lead to ketoacidosis.
Insulin normally suppresses lipolysis, and thus insulin-resistant adipocytes release too many fatty acids into circulation, many of which are taken up by hepatocytes and esterified into triglyceride. Thus, insulin resistance further exacerbates hepatic steatosis, which will in turn worsen insulin resistance in the liver.
Given this vicious cycle, abatement of hepatic steatosis is one of the mainstays of diabetes treatment. Metformin is one such treatment and works by activating fatty acid degradation and inhibiting fatty acid synthesis. Which of the following could be the mechanism of action of metformin?
(A) activation of protein phosphatase 2A
(B) AMP mimic that binds to the AMPK allosteric site
(C) ATP mimic that binds to the AMPK allosteric site
(D) increased movement of citrate into the cytoplasm
(E) malonyl CoA mimic that binds to the CAT-1 allosteric site
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- Which of these enzymes/complexes will insulin activate in the liver? Choose all that apply. Glycogen synthase Glycogen phosphorylase Acetyl-CoA carboxylase Carnitine shuttle PFK-1 FBPase-1arrow_forwardBlood sugar homeostasis: Indicate the order of events that will happen following blood glucose increase after a meal. Increased blood glucose 1 2 3 4 LO 5 6 :::: Glucose transport via GLUT4 Glucose transport into pancreatic cells Insulin binds to insulin receptor Insulin release from pancreatic beta-cells Second messenger signaling pathway is activated GLUT4 moves to plasma membrane Decreased blood glucose AND muscle makes ATP and glycogenarrow_forwardAfter absorption, nearly all fructose enters hepatocytes (liver cells) on the first pass and enters glycolysis for energy production, or if consumed in excess will get transformed into triglycerides. True Falsearrow_forward
- The hormone that directly stimulates metabolism by increasing lipolysis and indirectly stimulates metabolism by causing target cells to make IGFs isarrow_forwardInsulin signals activate all of the following enzymes except: Phosphoinositide 3-kinase (PI3K) Glycogen synthase kinase 3 (GSK3) Protein kinase B (PKB; or Akt) All of the above enzymes are activated by insulin signals Citrate move in and out of mitochondria via a specific transport protein. What would happen if aninhibitor completely inhibited this transport system? Fatty acid biosynthesis would slow down Ketone body synthesis would slow down Both A and B Neither A nor Barrow_forwardArrange the step in the dropdown menu in the image.arrow_forward
- This is a question assigned after reading the case study available here https://sciencecases.lib.buffalo.edu/files/statins.pdf HMG CoA reductase is activated by insulin signaling, and inhibited by glucagon signaling. Explain why insulin resistance and type II diabetes often are accompanied by elevated cholesterol levels.arrow_forwardHow does the pancreas combat low blood glucose levels? What part of the body is the target of this pancreatic action? What can happen at that tissue to solve the low blood glucose problem (list pathway[s])?arrow_forwardWhich of the following is NOT a fate of pyruvate in metabolism? .. Conversion to alanine as its storage form or for use by peripheral tissues such as skeletal muscles. Conversion to acetyl CoA for complete oxidation in the TCA cycle. Conversion to oxaloacetate in gluconeogenesis Conversion to lactate in a completely anaerobic process. L. Conversion to phophoenolpyruvate for the synthesis of glucosearrow_forward
- Which of the following are mechanisms that prevent the liver from using up glucose that is more urgently required by other tissues? (select all that apply) Group of answer choices Glucokinase (the liver's version of hexokinase) has a lower affinity for glucose than hexokinase does GLUT2 has a lower affinity for glucose than GLUT4 does The liver produces insulin when blood glucose levels are low The liver does not express a phosphofructokinase enzyme The liver increases glycolysis in response to glucagonarrow_forwardWhen the energetic needs of hepatocytes are being met, which of the following occurs? Acetyl-CoA inhibits pyruvate carboxylase. ATP inhibits fructose 1,6-bisphosphatase (FBPase1). ATPactivatesglycogenphosphorylase(phosphorylasea). Acetyl-CoA stimulates pyruvate kinase. None of the above Please answer asap and in short and content should not be palgarised pleasearrow_forwardThe previous answers were wrongarrow_forward
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