Podcast
Questions and Answers
Which of the following triggers the reversal of glycogenesis?
Which of the following triggers the reversal of glycogenesis?
What is the byproduct of adding new glucose molecules to an existing glycogen molecule?
What is the byproduct of adding new glucose molecules to an existing glycogen molecule?
During which state is glycogenesis activated?
During which state is glycogenesis activated?
What is the enzyme responsible for removing phosphate groups from glucose in the liver?
What is the enzyme responsible for removing phosphate groups from glucose in the liver?
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Which of the following is a characteristic of glycogenolysis?
Which of the following is a characteristic of glycogenolysis?
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What is the precursor molecule used for glycogen synthesis?
What is the precursor molecule used for glycogen synthesis?
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Which of the following enzymes is involved in glycogen synthesis?
Which of the following enzymes is involved in glycogen synthesis?
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What is the role of glycogenin in glycogen synthesis?
What is the role of glycogenin in glycogen synthesis?
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Which of the following is a consequence of glycogenolysis?
Which of the following is a consequence of glycogenolysis?
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When is glycogenesis stopped?
When is glycogenesis stopped?
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Study Notes
Glycolysis and ATP
- 6 ATP are consumed during glycolysis, producing a net gain of 2 ATP.
- Fatty acids are stored as triglycerides, while amino acids are utilized for protein synthesis.
- High concentrations of glucose react with proteins, necessitating safe storage.
Glycogenesis
- Glycogenesis refers to the creation and storage of glucose as glycogen.
- Activated during rest after the Cori cycle and in response to insulin signaling excess glucose.
- Primarily occurs in muscle cells and liver tissues.
Glycogen Structure
- Glycogen is a branched polysaccharide, allowing multiple access points for glucose release.
- Core protein glycogenin is surrounded by branches of glucose units, with each granule containing approximately 30,000 glucose units.
Glycogenesis Process
- The synthesis begins with the conversion of glucose to glucose-1-phosphate, followed by bonding to uridine triphosphate (UTP) to form UDP-glucose.
- Glycogen synthase and glycogen branching enzyme are crucial in glycogen formation.
Glycogenolysis
- Glycogen breakdown, initiated by glycogen phosphorylase, cleaves α 1,4-bonds until four residues remain adjacent to the α 1,6 bond.
- Glucan transferase moves residues, while a debranching enzyme releases free glucose from the remaining bond.
- Resulting glucose-1-phosphate is converted to glucose-6-phosphate for reentry into glycolysis.
Glycogen Storage and Function
- Liver glycogen serves as a storage for dietary glucose, constituting up to 8% of liver weight post-meal.
- Liver glycogen can be released to supply glucose for the entire body, lasting approximately 8-12 hours.
- Muscle glycogen acts as an immediate reserve for muscle energy; it cannot be released into the bloodstream due to the absence of the necessary enzyme.
- "Hitting the wall" refers to the depletion of glycogen reserves in endurance sports, ideally occurring as athletes finish the race.
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Description
Test your knowledge on glycolysis, glycogenesis, and the regulation of these metabolic pathways. Explore how ATP is both used and created, and understand the storage of glucose and fatty acids in the body.
