30 Questions
What is the primary function of glycogen phosphorylase in the process of glycogenolysis?
It catalyzes the phosphorylytic cleavage of the 1 → 4 linkages of glycogen to yield glucose-1-phosphate.
What is the role of the debranching enzyme in the process of glycogenolysis?
It transfers a trisaccharide unit from one branch to the other, exposing the 1 → 6 branch point.
How does the decrease in insulin secretion during the fasting state affect glucose uptake by skeletal muscle and adipose tissue?
It decreases glucose uptake by these tissues.
What is the role of glucose-6-phosphatase in the process of glycogenolysis?
It hydrolyzes glucose-6-phosphate to release glucose into the bloodstream.
What is the effect of the increase in glucagon secretion during the fasting state on the activity of glycogen synthetase and glycogen phosphorylase in the liver?
It inhibits glycogen synthetase and activates glycogen phosphorylase.
What is the fate of the glucose-1-phosphate produced during glycogenolysis?
It is converted to glucose-6-phosphate and then hydrolyzed to release glucose.
What is the primary function of glycogen in the liver?
To maintain blood glucose levels during fasting
After how many hours of fasting are liver glycogen concentrations almost completely depleted?
12-18 hours
What is the primary function of muscle glycogen?
To provide energy for muscle contraction
Which metabolic pathway utilizes glucose-6-phosphate as a substrate?
All of the above
What is the primary function of the pentose phosphate pathway?
To provide reducing equivalents (NADPH) for fatty acid synthesis
What is the primary difference between glycogen and starch?
Glycogen is found in animals, while starch is found in plants
What is the primary role of glucokinase in the liver?
To convert glucose to glucose-6-phosphate when blood glucose levels are high
What is the primary role of glycogen in the muscle?
To provide a source of glucose-6-phosphate for glycolysis in response to the need for ATP for muscle contraction.
Which of the following statements about the role of insulin in liver metabolism is true?
Insulin stimulates the activity of glucokinase in the liver
What is the primary role of glycogen in the liver?
To provide free glucose for export to maintain the blood glucose concentration.
What is the signal for increased cAMP formation in muscle?
The action of norepinephrine, which is secreted in response to fear or fright.
What happens when adequate amounts of ATP are synthesized in the mitochondria of liver cells?
Regulatory enzymes of the citric acid cycle are blocked, leading to citrate accumulation
What is the consequence of citrate accumulation in the cytoplasm of liver cells?
It initiates lipogenesis and cholesterol biosynthesis
What is the mechanism by which glycogen phosphorylase is activated and inactivated in both liver and muscle?
Glycogen phosphorylase is activated by phosphorylation catalyzed by phosphorylase kinase and inactivated by dephosphorylation catalyzed by phosphoprotein phosphatase.
What is the result of inhibiting phosphofructokinase-1 (PFK-1) activity in liver cells?
It leads to the accumulation of glucose-6-phosphate in the cytoplasm
Which hormones can activate glycogen phosphorylase in both liver and muscle?
Glucagon and epinephrine.
What is the primary function of the citric acid cycle in liver cells?
To generate ATP through oxidative phosphorylation
What is the role of the allosteric effectors 5' AMP and Ca2+ in the regulation of glycogen phosphorylase in muscle?
5' AMP and Ca2+ are positive allosteric effectors that enhance the activity of glycogen phosphorylase.
Which of the following statements about glycogenesis is correct?
It is the process of synthesizing glycogen from glucose.
Why is there an ample supply of glucose in the fed state?
Glucose is absorbed from the digestion of carbohydrates via the hepatic portal vein.
Which of the following statements about glycolysis is correct?
It can function either aerobically or anaerobically, depending on the availability of oxygen and the electron transport chain.
Which of the following enzymes is specific to glucose?
Glucokinase
In which tissues is glucokinase present?
Liver and pancreatic beta cells
Which of the following statements about the brain's energy requirements is correct?
The brain has a substantial requirement for glucose, even during prolonged fasting.
Test your knowledge on Glycogenesis and Glycogenolysis processes in metabolism. Topics include the synthesis and breakdown of glycogen, and the role of glucose in meeting energy needs. Get ready to dive into the details of carbohydrate metabolism!
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
