5 Written questions
5 Matching questions
- What role does UDP-glucose play in Glycogen synthesis?
- What are the properties of the presumptive branch point?
- What is debranching?
- What are the properties of branching?
- What is glycogen?
- a Glycogen synthesis involves transfer of glucose from UDP-glucose to a growing chain
- b A very large, branched polymer of glucose residues. Most of the glucose residues are linked by alpha 1,4 glycosidic bonds. branches about every 10th residue are linked by alpha 1,6 glycosidic bonds
- c When glucose residues are removed to the "limit dextran" which is the 4th glucose residue from the branch glucose
- d Must be at least 4 residues away from other branches. Links are alpha 1,6 glycosidic bond
- e Utilizes a non branched string of at least 11 glycosyl residues long. Branching enzyme transfers a string of typically 7 residues from non reducing end to presumptive branch point.
5 Multiple choice questions
- Glucose-1-phosphate +UTP =>UDP-glucose + PPi
- Glucose 6 phosphatase converts Glucose 6 phosphate into glucose for export out of the liver and transport to other tissues
- Uridine diphosphate is a nucleotide composed of uracil, ribose and pyrophosphate
- A glycosyl unit from UDP glucose is transferred to the hydroxyl group at the C4 of the terminal glucose residue forming a alpha 1,4 glycosidic bond. Requires a glycogen molecule that is a minimum of 4 residues to which a glycosyl will be added
- Glycogen (n residues) + Pi=> glucose-1-phosphate + Glycogen (n-1 residues)
5 True/False questions
How is UDP-glucose formed? → Glycogenin is both an enzyme and its substrate consisting of two 37 kD subunits. Each subunit catalyzes addition of a glycosyl unit from UDP glucose to Tyr 194 of other subunit. Subsequently, 7 more glycosyl units are added so that 8 glycosyl units are attached to Tyr 194 for each subunit
What enzyme catalyzes the transfer of glucose from UDP-glucose to a growing chain? → Glucose-1-phosphate +UTP =>UDP-glucose + PPi
Why is branching important in glycogen synthesis? → Increases the number of terminal glucose residues which are site of action for glycogen phosphorylase and synthase. Branching increases rate of glycogen synthesis and degradation
What irreversible reaction drives the synthesis of UDP-glucose? → PPi+ H2O=> 2Pi
What does transferase do? → A very large, branched polymer of glucose residues. Most of the glucose residues are linked by alpha 1,4 glycosidic bonds. branches about every 10th residue are linked by alpha 1,6 glycosidic bonds