Biochem: 1 1. Identify if the following enzymes in the liver are active, inactiv
ID: 72078 • Letter: B
Question
Biochem:
1
1. Identify if the following enzymes in the liver are active, inactive or unaffected during fasting
a. Branching Enzyme -
b. Debranching Enzyme -
c. Glycogen Synthase -
d. Glycogen Phosphorylase -
e. Glucokinase -
2. Explain the outcomes of each of the following Glycogen Storage Diseases
a. Lack of Debranching Enzyme -
b. Lack of Muscle Glycogen –
c. Lack of Glut-2 transporters -
d. Lack of Branching Enzyme –
e. Lack of Liver Glycogen Synthase -
f. Lack of Glucose-6-Phosphatase -
g. Lack of Liver Glycogen –
3. Explain why Branching Enzyme and Debranching Enzyme are needed in glycogen metabolism.
4. Suppose a mutation occurs in Phosphoglucomutase which does not allow the enzyme to catalyze the movement of the phosphate group from the 6 position of glucose to the 1 position. What would be the effects of this mutation in Glycogen metabolism?
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4. Suppose a mutation occurs in Phosphoglucomutase which does not allow the enzyme to catalyze the movement of the phosphate group from the 6 position of glucose to the 1 position. What would be the effects of this mutation in Glycogen metabolism?
5. Liver glycogen is used in fasting to provide glucose for use by other tissues including the brain. Muscle glycogen is not. What is the explanation for this?
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4. Suppose a mutation occurs in Phosphoglucomutase which does not allow the enzyme to catalyze the movement of the phosphate group from the 6 position of glucose to the 1 position. What would be the effects of this mutation in Glycogen metabolism?
5. Liver glycogen is used in fasting to provide glucose for use by other tissues including the brain. Muscle glycogen is not. What is the explanation for this?
6. Which of the following statements about the control of glycogen synthase are correct? Select all that apply.
a) Glycogen synthase is inactivated by a protein phosphatase.
b) Glycogen synthase is activated in the presence of insulin.
c) PKA and glycogen synthase kinase 3 phosphorylate glycogen synthase at different sites.
d) The phosphorylation by glycogen synthase kinase 3 is inhibited by insulin.
e) Insulin activates protein kinase B which phosphorylates glycogen synthase.
Explanation / Answer
1. e. Glucokinase- Thus, glycolysis is inhibited in the liver but unaffected in muscle when fasting. ... prevent pyruvate kinase from being active at the same time as the enzymes.
2. e. Lack of Liver Glycogen Synthase - Glycogen storage disease type IX (also known as GSD IX) is a condition ... The enzyme is made up of 16 subunits, four each of the alpha, beta, gamma, and ... Although the effects of gene mutations on the respective protein subunits are ... You may find the following resources about glycogen storage disease type IX.
3. A debranching enzyme is a molecule that helps facilitate the breakdown of glycogen, which serves as a store of glucose in the body, through glucosyltransferase and glucosidase activity. Together with phosphorylases, debranching enzymes mobilize glucose reserves from glycogen deposits in the muscles and liver. This constitutes a major source of energy reserves in most organisms. Glycogen breakdown is highly regulated in the body, especially in the liver, by various hormones including insulin and glucagon, to maintain a homeostatic balance of blood-glucose levels.[1] When glycogen breakdown is compromised by mutations in the glycogen debranching enzyme, metabolic diseases such as Glycogen storage disease type III can result
4. Phosphoglucomutase is defective. The enzyme catalyzes conversion of glucose-1-phosphate to ... Skeletal muscle glycogen is not a source of blood glucose b/c muscle ... No glucose-6-phosphate can enter glycolysis, so lactate formation ... There exists a mutant strain that is defective in only one enzyme.
5. Equivalent or closely related terms include famine response, starvation mode, ... intake by burning fat reserves and consuming muscle and other tissues. ... of the digestive tract along with glycogen reserves stored in muscle and liver cells. ... if a non-brain tissue is using fatty acids as its metabolic fuel.
6. b) Glycogen synthase is activated in the presence of insulin.
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