Glycogen Synthesis and Regulation

Why is there glycogen in the liver?

Which is correct of glycogen in the liver?

The only source of glucose to supply the muscles is the glycogen.

Which linkages occur between adjacent glucose monomers in glycogen?

Which linkages occur between glucose monomers and their neighbouring molecules in branches in glycogen?

The enzymes at the beginning and/or end of a biosynthetic pathway will be tightly regulated.

Why, in biosynthetic pathways, is at least one enzymatic reaction irreversible?

What is the first reaction in the synthesis of glycogen?

Where is hexokinase present?

Glucokinase is present in the liver and pancreatic B cells only.

Phosphorylation of glucose to glucose-6-phosphate is carried out by which enzyme(s)?

What is the role of phosphoglucomutase in glycogen synthesis?

Which enzyme catalyses the formation of UDP glucose from UTP and glucose 1-phosphate?

What is the structure of uridine triphosphate (UTP)?

What is a co-product of UDP glucose formation?

What does UTP react with on glucose 1-phosphate to form UDP glucose?

What amino acid does glycogenin bind to in the protein primer?

Which carbon of UDP-glucose does tyrosine bind to in the protein primer?

When the tyrosine-glycogenin protein primer binds to UDP-glucose, UDP is cleaved off.

Which enzyme catalyses the addition of the tyrosine-glycogenin primer to UDP-glucose causing the cleavage of UDP?

How does the chain extend from glucose once it has been bound to the tyrosine-glycogenin primer?

Which statement is true of branching in glycogen?

Fill in the blanks below to summarise the synthesis of glycogen. 1. First, [blank_start]glucose[blank_end] is phosphorylated to [blank_start]glucose-6-phosphate[blank_end]. This is catalysed by [blank_start]hexokinase[blank_end] or [blank_start]glucokinase[blank_end] in the liver. 2. Then, [blank_start]glucose 6-phosphate[blank_end] is isomerised to [blank_start]glucose 1-phosphate[blank_end]. This is catalysed by [blank_start]phosphoglucomutase[blank_end]. 3. [blank_start]Glucose 1-phosphate[blank_end] reacts with [blank_start]UTP[blank_end] to form [blank_start]UDP-glucose[blank_end], releasing [blank_start]PPi[blank_end] in the process. This reaction is catalysed by [blank_start]UDP-glucose pyrophosphorylase[blank_end]. 4. The enzyme [blank_start]glucosyltransferase[blank_end] binds a protein primer in the form of the amino acid [blank_start]tyrosine[blank_end] bound to [blank_start]glycogenin[blank_end] to the 1st carbon of [blank_start]UDP glucose[blank_end]. This causes the cleavage of [blank_start]UDP[blank_end]. 5. Additional [blank_start]UDP-glucose[blank_end] monomers join via [blank_start]a-1,4[blank_end] linkages in reactions catalysed by [blank_start]glycogen synthase[blank_end]. 6. This process repeats to form a chain. 7. Portions of the core chain are transferred to form [blank_start]a-1,6[blank_end] linkages with the chain itself to form branches.

The active form of glycogen synthase is what?

What enzyme do we require to activate glycogen synthase?

Insulin activates a protein phosphatase which dephosphorylates glycogen synthase to activate it.

What happens first in glycogen breakdown?

What enzyme carries out the phosphorylation of glucose monomers in glycogen during breakdown?

What does glycogen transferase do?

Which enzyme cleaves a-1,6 linkages on glycogen?

Glucose 1-phosphate from the breakdown of glycogen is converted to glucose 6-phosphate by phosphoglucomutase

Glucose-6-phosphate is only converted to glucose in the liver

Fill in the blanks below to describe glycogen breakdown. 1. First, an [blank_start]inorganic source[blank_end] phosphorylates glucose monomers to break their [blank_start]a-1,4[blank_end] linkages and release them. This is catalysed by [blank_start]glycogen phosphorylase[blank_end]. 2. Then, glycogen [blank_start]branches[blank_end] are removed and added to the core chain by [blank_start]glycogen transferase[blank_end]. This leaves behind a single branched glucose monomer with an [blank_start]a-1,6[blank_end] linkage. 3. This [blank_start]a-1,6[blank_end] linkage is broken by [blank_start]a-1,6-glucosidase[blank_end]. 4. [blank_start]Glucose 1-phosphate[blank_end] is isomerised to [blank_start]glucose 6-phosphate[blank_end] by [blank_start]phosphoglucomutase[blank_end]. 5. In the liver, [blank_start]glucose 6-phosphate[blank_end] is converted to [blank_start]glucose[blank_end] by the [blank_start]glucose 6-phosphatase[blank_end] enzyme. The muscle does not have this enzyme, so its [blank_start]glucose 6-phosphate[blank_end] enters the [blank_start]glycolysis[blank_end] pathway.

The active form of glycogen phosphorylase is what?

What enzyme do we require to activate glycogen phosphorylase?

By what mechanism is glycogen protein kinase activated?

Adrenaline activates glycogen breakdown in the [blank_start]muscle[blank_end]. Glucagon activates glycogen breakdown in the [blank_start]liver[blank_end]. Insulin activates glycogen breakdown in [blank_start]both[blank_end].

Where does calcium released from the sarcoplasmic reticulum bind on glycogen phosphorylase kinase?

What effect does calcium in muscle cells have on glycogen breakdown?

Why is it important that calcium can regulate glycogen breakdown in the muscles?

What effect does AMP have on glycogen phosphorylase?

Why is it important that AMP concentration regulates glycogen breakdown?

ATP is an allosteric inhibitor of glycogen phosphorylase.

Fill in the blanks to describe each glycogen storage disease. [blank_start]Von Gierke's[blank_end] disease is caused by defective glucose 6-phosphatase. [blank_start]Pompe's[blank_end] disease is caused by defective lysosomal glycosidase. [blank_start]McArdle's[blank_end] disease is caused by defective glycogen phosphorylase.

Which of the following are logical symptoms of Von Gierke's disease?

Which of the following are logical symptoms of Pompe's disease?

Which of the following are logical symptoms of McArdle's disease?

What causes red/brown urine following exercise in those with McArdle's disease?