Gluconeogensis, glycogenolysis and glycogenesis
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Questions and Answers

Which enzyme is responsible for the conversion of glycerol into dihydroxyacetone phosphate?

  • Debranching enzyme
  • Phosphoglucomutase (correct)
  • Glycogen phosphorylase
  • Glucose-6-phosphatase

    • What type of bond does glycogen primarily consist of in its structure?

  • Beta 1,4 glycosidic bond
  • Alpha 1,4 glycosidic bond (correct)
  • Hydrogen bond
  • Ester bond

    • Which enzyme is involved in transferring glucose residues from an a-1,6 linkage to a-1,4 linkage in glycogen?

  • Debranching enzyme (correct)
  • Phosphoglucomutase
  • Glycogen phosphorylase
  • Glucose-6-phosphatase

    • Which enzyme is essential for the conversion of glucose 6-phosphate into glucose?

    <p>Glucose-6-phosphatase</p> Signup and view all the answers

    In glycogenolysis, what is the role of glycogen phosphorylase?

    <p>Breakdown of glycogen by cleaving its structure</p> Signup and view all the answers

    Which process involves the conversion of glucose 1-phosphate to glucose 6-phosphate for further metabolism?

    <p>Debranching of glycogen</p> Signup and view all the answers

    What enzyme is responsible for cleaving the 1,6-glycosidic bond present in glycogen structure?

    <p>Debranching enzyme</p> Signup and view all the answers

    Which enzyme plays a critical role in the events of glycogenolysis?

    <p>Glycogen phosphorylase</p> Signup and view all the answers

    What is the primary function of fructose 2,6-bisphosphate in the context of glycolysis and gluconeogenesis?

    <p>Inhibits glycolysis and activates gluconeogenesis</p> Signup and view all the answers

    How does insulin affect the formation of fructose 2,6-bisphosphate?

    <p>Stimulates the formation of fructose 2,6-bisphosphate</p> Signup and view all the answers

    Which enzyme is activated by fructose 2,6-bisphosphate in glycolysis?

    <p>Phosphofructokinase 1</p> Signup and view all the answers

    How does glucagon affect the formation of fructose 2,6-bisphosphate?

    <p>Decreases the formation of fructose 2,6-bisphosphate</p> Signup and view all the answers

    Which process does Fructose 1,6-bisphosphatase stimulate?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What is the primary function of the Cori cycle?

    <p>Clears lactate by converting it back to glucose</p> Signup and view all the answers

    In the glucose alanine cycle, what happens to glucose in muscle tissues?

    <p>Metabolizes to produce pyruvate</p> Signup and view all the answers

    Which molecule can be stored as glycogen or return to muscle tissue according to the text?

    <p>Glucose</p> Signup and view all the answers

    What is the primary function of gluconeogenesis?

    <p>Synthesize glucose from non-carbohydrate precursors</p> Signup and view all the answers

    Which of the following is a source of pyruvate in gluconeogenesis?

    <p>Alanine</p> Signup and view all the answers

    In which organelle does the formation of oxaloacetate take place?

    <p>Mitochondria</p> Signup and view all the answers

    What is the role of ATP in the formation of oxaloacetate?

    <p>Provides energy for the reaction</p> Signup and view all the answers

    What is the purpose of converting oxaloacetate into malate in the mitochondria?

    <p>To transport oxaloacetate out of the mitochondria</p> Signup and view all the answers

    What is the role of phosphoenolpyruvate carboxykinase in gluconeogenesis?

    <p>Converts oxaloacetate into phosphoenolpyruvate</p> Signup and view all the answers

    What is the final step of gluconeogenesis?

    <p>Conversion of glucose 6-phosphate into glucose</p> Signup and view all the answers

    Where is the enzyme glucose 6-phosphatase located?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What prevents the conversion of glucose 6-phosphate into glucose in muscle tissue?

    <p>Absence of glucose-6-phosphatase</p> Signup and view all the answers

    Which hormone is released from adrenal glands during the 'flight or fight' response?

    <p>Epinephrine</p> Signup and view all the answers

    What is the role of Ca2+ in muscle tissue with respect to glycogenolysis?

    <p>Activates glycogenolysis</p> Signup and view all the answers

    What is the role of insulin in the regulation of glycogen synthase?

    <p>Activates glycogen synthase</p> Signup and view all the answers

    Which hormone triggers the conversion of phosphorylase b to phosphorylase a?

    <p>Epinephrine</p> Signup and view all the answers

    What is the role of the delta subunit of phosphorylase kinase in muscle tissue?

    <p>Regulates glycogenolysis</p> Signup and view all the answers

    Which process involves the conversion of lactate to pyruvate?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What is the role of glucagon in the regulation of glycogenolysis?

    <p>Activates glycogenolysis</p> Signup and view all the answers

    In gluconeogenesis, which enzyme is responsible for the conversion of pyruvate to oxaloacetate?

    <p>Pyruvate carboxylase</p> Signup and view all the answers

    Which of the following is NOT an inhibitor of phosphofructokinase?

    <p>Fructose 2,6-bisphosphate</p> Signup and view all the answers

    What is the net effect when glycolysis and gluconeogenesis occur simultaneously in the liver?

    <p>ATP hydrolysis</p> Signup and view all the answers

    Which of the following stimulates the conversion of fructose 6-phosphate to fructose 2,6-bisphosphate?

    <p>None of the above</p> Signup and view all the answers

    What is the function of glucose 6-phosphatase in gluconeogenesis?

    <p>to convert glucose 6-phosphate to glucose</p> Signup and view all the answers

    What is the effect of glucagon on glycolysis?

    <p>inhibition</p> Signup and view all the answers

    Which of the following is NOT a regulator of gluconeogenesis?

    <p>Citrate</p> Signup and view all the answers

    What is the function of phosphoenolpyruvate carboxykinase in gluconeogenesis?

    <p>to convert oxaloacetate to phosphoenolpyruvate</p> Signup and view all the answers

    What enzyme is responsible for the breaking down of glycogen?

    <p>Glycogen phosphorylase</p> Signup and view all the answers

    What is the main source of glucose for the Cori cycle?

    <p>Lactate</p> Signup and view all the answers

    What is the primary function of the glucose alanine cycle?

    <p>To transport pyruvate from muscle tissues to the liver for gluconeogenesis</p> Signup and view all the answers

    Which enzyme is essential for the generation of glucose from glycerol?

    <p>Glycerol kinase</p> Signup and view all the answers

    How is phosphorylase b converted into the active form phosphorylase a?

    <p>Hormones trigger the conversion by stimulating the release of phosphate groups</p> Signup and view all the answers

    What is the role of calmodulin in muscle glycogen breakdown?

    <p>Calmodulin is the delta subunit of glycogen phosphorylase kinase that activates the enzyme in response to calcium ions</p> Signup and view all the answers

    How does insulin contribute to glycogen synthesis?

    <p>Insulin promotes glycogen synthesis by activating protein phosphatase 1 to convert active glycogen synthase to an inactive form</p> Signup and view all the answers

    What is the conversion process of glucose to glucose 6-phosphate in glycogenesis?

    <p>Glucose is converted to glucose 6-phosphate by hexokinase</p> Signup and view all the answers

    Which hormone triggers the activation of glycogen phosphorylase for glycogen breakdown?

    <p>Epinephrine</p> Signup and view all the answers

    What hormone stimulates the release of glucose into the blood by promoting glycogen breakdown in the liver?

    <p>Glucagon</p> Signup and view all the answers

    Glycerol is converted into glucose 6-phosphate without the formation of dihydroxyacetone phosphate.

    <p>False</p> Signup and view all the answers

    Glycogen is a linear chain of glucose molecules.

    <p>False</p> Signup and view all the answers

    Glucose 1-phosphate can be directly converted into glucose 6-phosphate by glycogen phosphorylase.

    <p>False</p> Signup and view all the answers

    The Cori cycle is a process that involves the conversion of lactate to pyruvate.

    <p>False</p> Signup and view all the answers

    Gluconeogenesis is the process of generating glucose from non-carbohydrate sources such as glycerol and amino acids.

    <p>True</p> Signup and view all the answers

    In gluconeogenesis, the formation of oxaloacetate occurs in the cytoplasm.

    <p>False</p> Signup and view all the answers

    The enzyme glucose 6-phosphatase is present in the mitochondria.

    <p>False</p> Signup and view all the answers

    Gluconeogenesis occurs only in the liver.

    <p>False</p> Signup and view all the answers

    Phosphoenolpyruvate carboxykinase is responsible for the formation of malate and mitochondrial exit.

    <p>False</p> Signup and view all the answers

    Gluconeogenesis is the process of breaking down glycogen to glucose.

    <p>False</p> Signup and view all the answers

    Muscle cells can directly convert glucose 6-phosphate back into glucose.

    <p>False</p> Signup and view all the answers

    Glycogen synthase is activated by phosphorylation.

    <p>False</p> Signup and view all the answers

    Glucagon stimulates glycogen synthesis in the liver.

    <p>False</p> Signup and view all the answers

    Lactate is a direct precursor of glucose in gluconeogenesis.

    <p>True</p> Signup and view all the answers

    The Cori cycle involves the conversion of lactate from muscle tissue to glucose in the liver.

    <p>True</p> Signup and view all the answers

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