Lecture 22 (Exam 2) Flashcards
This is a long chain homopolymer of glucose molecules with branches.
Glycogen
In glycogen, the glucose molecules within the chain are linked together via…
alpha-1,4 glycosidic bonds
In glycogen, the branch points formed __________ bonds between glucose monomers of separate chains.
alpha-1,6 glycosidic bonds
_________ ends each contain a terminal glucose with a free hydroxyl group at carbon 4.
Non-reducing
_________ end consists of glucose monomer connected to a protein called glycogenin.
Reducing
Glycogen is stored where?
In the liver, muscle, and other tissues
Glycogen is stored as ________ that contain not only glycogen but also the enzymes needed for glycogen metabolism. Defects in these enzymes can lead to disorders.
Granules
_______ glycogen regulates blood glucose levels.
Liver
_______ glycogen provides reservoir of fuel (glucose) for physical activity.
Muscle
Glycogen metabolism is the regulated storage and release of ________.
Glucose
Regulation of glycogen metabolism depends on ________ control, ________ modification through reversible phosphorylation of key enzymes, and ________ control.
Allosteric
Covalent
Hormonal
What is the rate limiting enzyme of glycogenesis?
Glycogen synthase
Glycogen synthase catalyzes the transfer of glucose from UDP-glucose to non-reducing end of glycogen chain. Forms ________ bonds between glucose molecules.
alpha-1,4 glycosidic bonds
When the glycogen chain reaches _____ residues, a fragment of the chain (about 7 residues long) is broken off at an alpha-1,4 link and reattached elsewhere through an ________ link by ________ ________. The new branch point must be at least 4 residues away from a preexisting branch.
11
alpha-1,6 (glycosidic bond)
glucosyl (4:6) transferase
Branching increases _________ of glycogen and increases number of terminal _________ ends.
Solubility
Non-reducing
T/F. Branching of glycogen increases the rate at which glycogen can be synthesized and degraded.
True
What is the rate-limiting enzyme of glycogenolysis?
Glycogen phosphorylase
Glycogen is broken down to release…
Glucose 1-Phosphate Glycogen remnant (Glycogen n-1)
In glycogenolysis, glucose 1-phosphate is converted to…
Glucose 6-phosphate
Glucose 6-phosphate can be used for ________, free glucose for release into the _______ _______, or to the pentose phosphate pathway – NADPH and ribose derivative.
Glycolysis
Blood stream
Glucose 6-phosphate cannot get out of the cell and only the liver has glucose 6-phosphatase. This converts it to _______ which can be released into the blood stream.
Glucose
________ transfers a block of 3 of the remaining 4 glucose to the non-reducing end of the main chain forming an alpha-1,4 bond.
Transferase
This is what cleaves the alpha-1,6 bond of the single remaining glucose residue to release the free glucose.
alpha-1,6 glucosidase
Glycogen phosphorylase adds an _________ and releases a glucose residue as glucose 1-phosphate. It also uses _________ _________ as a cofactor.
Orthophosphate Pyridoxal phosphate (Vitamin B6)
