25 Questions
What is the major fate of glucose in animal tissues?
Breakdown in the glycolysis pathway followed by oxidation in the citric acid cycle
By what means is glycogen stored in vertebrates and starch stored in plants?
Polymeric storage form
How is glycogen regulated allosterically and hormonally in vertebrates?
By insulin and glucagon
Where is glycogen primarily stored in the body?
In the liver and muscle
Which product is excess glucose mainly converted into in the diet?
Glycogen
What are cytosolic granules mainly composed of in terms of storage?
Glycogen
What is the basic structure of amylopectin?
Branched structure with (α1→4) linkages
Which polysaccharide has more branching than amylopectin?
Glycogen
What is the product obtained by removing a glucose residue from the non-reducing end of a glycogen chain?
Glucose-1-P
Which enzyme is responsible for breaking down glycogen in muscle and liver?
Glycogen Phosphorylase
What is the function of liver glycogen?
Serve as a reservoir of glucose for other tissues
Why is glycogen important for neurons of the brain and red blood cells?
It serves as a reservoir of glucose
Why is the oxidation of the anomeric carbon C1 of glucose significant?
Basis for the Fehling's reaction
What is the role of glycogen in vigorously contracting muscle?
Provide a quick source of energy
Why can't C-1 of glucose be oxidized by Cu2+ in its ring form?
Is in equilibrium with the open-chain form
What is the primary function of the liver in relation to glucose metabolism, compared to muscle?
The liver releases glucose into the bloodstream to supply other tissues, while muscle uses glucose for its own energy needs.
What is the role of the glucose 6-phosphate transporter (T1) in the liver?
T1 transports glucose 6-phosphate from the cytosol to the lumen of the ER, where it can be hydrolyzed by glucose 6-phosphatase.
What is the role of the glucose and phosphate transporters (T2 and T3) in the liver?
T2 and T3 transport glucose and phosphate, respectively, from the lumen of the ER to the cytosol.
What is the purpose of the dephosphorylation of glucose 6-phosphate in the liver?
To release glucose into the bloodstream for use by other tissues.
Where is the catalytic site of glucose 6-phosphatase located in the liver?
In the lumen of the endoplasmic reticulum (ER).
Which enzyme is responsible for initiating glycogen synthesis?
Phosphoglucomutase
Which of the following is the activated form of glucose used as a substrate for glycogen synthase?
UDP-glucose
Which of the following statements about muscle and adipose tissue is true?
They lack glucose 6-phosphatase, preventing gluconeogenesis.
What is the role of the nucleoside triphosphate (NTP) in the formation of a sugar nucleotide?
It donates the phosphate group to the sugar phosphate.
Which of the following statements about glycogen synthesis is true?
It involves the polymerization of hexoses using sugar nucleotides as intermediates.
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