Carbohydrate Metabolism Flashcards
What is glycolysis
The breakdown of a 6 carbon glucose molecule to produce a 3 carbon molecule of pyruvate
Which cells in the body can generate energy from glycolysis
Every cell in the body
How many steps are in glycolysis
10
In what type of cells is glycolysis the only energy pathway
Cells without a mitochondria
Which hormone activates glycolysis in resting conditions
Insulin
Which hormone inhibits glycolysis in resting conditions
Glucagon
In what conditions are we heavily reliant on anaerobic glycolysis
During severe intensity exercise (1-5 minutes) or when the PCR system has been depleted
What is the maximal rate of ATP synthesis using glycolysis
4.5 mmol/Kg
What is the time required to maximise ATP rates when exercise starts with glycolysis
5-10 seconds
What is the investment phase of glycolysis
First 5 reactions, ATP is used
What is the payoff phase of glycolysis
Reactions 6-10 where ATP is generated
What is the first step of glycolysis
Glucose is converted to glucose-6-phosphate by hexokinase (addition of phosphate to carbon 6), ATP is used
What is the function of the enzyme phsophofructokinase in step 3 of glycolysis
Converts fructose-6-phosphate to fructose 1,6-bisphosphate (addition of another phosphate to C1), ATP is used
What happens in step 4 of glycolysis
What is the function of pyruvate kinase in the final step of glycolysis
Convert PEP to pyruvate by removing phosphate, ATP generated
How many total molecules of ATP and how many net molecules of ATP does glycolysis produce per molecule of glucose
4 total, 2 net
Which type of glycolysis produces large amounts of lactic acid
Anaerobic
What is glycogenesis
Formation of new glycogen
What is glycogenolysis
Breakdown of glycogen
What are the two main sites of glycogen storage in the body
Liver and muscle
Which is the largest glycogen store in the body
Muscle
How is glucose released from glycogen in muscle
Released as glucose-6-phosphate specifically for muscle tissue
What is the difference between glucose released in liver and muscle cells
Glucose is released specifically for muscle from muscle stores, liver stores release glucose for other cells also
What is the function of phosphoglucomutase in glycogenesis
Moves phosphate from C6 to C1 in glucose-6-P to produce glucose-1-P
What does glucose-1-P bind to during glycogenesis to produce UDP glucose
UTP
Which enzyme attaches UDP glucose to other glucose molecules via alpha1-4 glycosidic linkages to form glycogen in glycogenesis
Glycogen synthase
When are glycogen molecules branched
After 11 or more chains have been formed
Which enzyme is required to break the alpha1-4 linkage in glycogen produced by glycogen synthase and reattach via alpha 1-6 linkages to form branches
Branching enzyme
How is glucose removed from the glycogen chain
Phosphorolysis
How much if the glycogen chain is broken down into glucose
Around 10%
How much of the glycogen chain is broken down into glucose-1-P
About 90%
Which enzyme is the rate limiting step in glycogenolysis
Glycogen phosphorylase
What is the role of glycogen phosphorylase in glycogenolysis
Breaks down the alpha 1-4 bonds until there is 4 glucose molecules remaining
What happens to the glucose-1-P released from the chain
Converted to glucose-6-P which is then used in glycolysis for energy or converted to glucose in the liver
Which enzymes break the 1-6 linkages
Debra Chung enzyme and glucan transferase
When is glycogenolysis unregulated in skeletal muscle
During high intensity exercise
