Which enzyme converts glucose-1-phosphate to glucose-6-phosphate?
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Phosphoglucomutase.
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Which enzyme converts glucose-1-phosphate to glucose-6-phosphate?
Phosphoglucomutase.
Where is the phosphate group located in Glucose 6-phosphate (G6P)?
On the sixth carbon atom.
How does the body store excess glucose?
By converting it into glycogen for storage.
What enzyme removes the terminal glucose residues from the nonreducing end of glycogen?
Glycogen phosphorylase.
How many glucose residues away from the (α1 to 6) branch point does glycogen phosphorylase stop removing glucose residues?
Four glucose residues.
What is the starting point of glycogen synthesis?
Glucose-6-phosphate.
What happens if the body has more glucose than it needs?
The excess glucose is stored.
Which enzyme resumes its reaction on the new unbranched polymer during glycogen breakdown?
Glycogen phosphorylase.
How quickly can muscle glycogen be depleted during vigorous exercise?
Muscle glycogen can be depleted in less than 1 hour during vigorous exercise.
What happens to the single glucose residue left at the branch point during glycogen breakdown?
It is released and can enter directly into glycolysis.
Can glucose-1-phosphate (G1P) enter glycolysis directly?
No, it cannot enter glycolysis.
What percentage of the liver's weight can glycogen represent?
Up to 10%.
What is the normal range for blood glucose levels in humans?
80 – 100 mg/dl.
Which enzyme is responsible for breaking down glycogen into glucose-1-phosphate?
Glycogen phosphorylase.
In what form is glycogen stored in liver and skeletal muscle?
In large cytosolic granules.
What is the main difference between G1P and G6P?
The position of the phosphate group; G1P has it on the first carbon, while G6P has it on the sixth carbon.
What is the end product of the glycogen phosphorylase reaction?
Glucose-1-phosphate.
What are the possible fates of glucose-6-phosphate (G6P) after its formation?
G6P can enter glycolysis, the pentose phosphate pathway (PPP), or replenish blood glucose.
Where is glycogen primarily found in vertebrates?
In the liver and skeletal muscle.
What is the role of liver glycogen in glucose metabolism?
Liver glycogen acts as a reservoir of glucose for other tissues when dietary glucose is not available (between meals or during fasting).
What is the role of the glycogen debranching enzyme in glycogen breakdown?
It helps in removing branches from glycogen to facilitate its breakdown.
Into what is glucose-6-phosphate converted during glycogen synthesis?
Glucose-1-phosphate and then to UDP-glucose.
What does G6P stand for?
Glucose 6-phosphate.
Where is the phosphate group located in Glucose 1-phosphate (G1P)?
On the first carbon atom.
How far must each new branch point be from the nearest existing branch point in glycogen?
At least 4 sugars away.
How long can liver glycogen storage last before being depleted?
Liver glycogen storage can be depleted in 12 to 24 hours.
In which tissues does glycogen breakdown occur to enter the glycolytic pathway?
Liver and skeletal muscles.
What is the product of the reaction catalyzed by glycogen phosphorylase?
Glucose-1-phosphate (G1P).
What does G1P stand for?
Glucose 1-phosphate.
What is the minimum length of a branch from which sugars are removed to form a new branch point in glycogen?
At least 11 sugars long.
How does the body maintain blood glucose levels despite varying carbohydrate intake?
Through digestion and absorption of carbohydrates as glucose, and gluconeogenesis.
Which enzyme converts glucose-1-phosphate to glucose-6-phosphate during glycogen breakdown?
Phosphoglucomutase.
What happens to excess glucose in vertebrates?
It is converted to glycogen for storage.
What percentage of muscle weight can glycogen represent?
1 to 2%.
What is the main learning objective of today's class?
To explain glycogen metabolism, including its breakdown and synthesis.
In which tissues can glycogen synthesis take place?
Almost all animal tissues.
In which tissues is glycogen synthesis especially prominent?
Liver and skeletal muscles.
Which enzyme is responsible for elongating the glycogen chain?
Glycogen synthase.
What is the immediate donor of glucose residues for glycogen synthesis?
UDP-glucose.
What enzyme transfers the branches during glycogen breakdown?
Glycogen debranching enzyme.
How does the body access stored glucose?
By breaking down glycogen into glucose.
What type of bonds are formed at the branch points of glycogen?
(α1 to 6) bonds.
What is the role of UDP-glucose in glycogen synthesis?
The glucose residue of UDP-glucose is transferred to the nonreducing end of a glycogen branch to make a new (α1 to 4) linkage.
What is the main topic you should be able to explain after today's class?
Glycogen metabolism (Breakdown and synthesis).
How many sugars are removed from a branch to create a new branch point in glycogen?
A chain of 6-7 sugars.
To which end of the glycogen branch is the glucose residue of UDP-glucose transferred?
The nonreducing end.
Which enzyme is responsible for creating the (α1 to 6) bonds in glycogen?
Glycogen-branching enzymes.
What type of linkage is formed when the glucose residue of UDP-glucose is added to the glycogen chain?
A new (α1 to 4) linkage.
