Glycolysis Flashcards
What are the two phases of glycolysis?
Investment phase & the payoff phase.
Describe the investment phase of glycolysis.
6-Carbon molecules.
Phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate.
Describe the payoff phase of glycolysis.
3-Carbon molecules.
Oxidative conversion of glyceraldehyde 3-phosphate to pyruvate and the coupled formation of ATP and NADH.
What is the overall reaction for glycolysis?
Glucose + 2(NAD+) + 2ADP + 2Pi –> 2Pyruvate + 2NADH + 2ATP + 2Water + 4(H+)
List the 3 control steps in glycolysis.
- Hexokinase
(glucose —> glucose 6-phosphate) - PFK-1
(fructose 6-phosphate —> fructose-1,6-bisphosphate) - Pyruvate kinase
(2 phosphenolpyruvate —> 2 pyruvate + 2 ATP)
Why is PFK-1 often called the pacemaker of glycolysis?
Sets the pace of glycolysis due to heavy regulation by allosteric activators and inactivators.
What are the fates of pyruvate?
AcCoA (aerobic oxidation)
lactate (anaerobic lactic acid fermentation)
ethanol (alcoholic fermentation)
What type of pathway (catabolic, anabolic, amphibolic) is glycolysis and in what cellular location does it occur?
Catabolic pathway (breaks down glucose) and occurs in the cytosol.
What are all of the fates of glucose-6-phosphate?
Glycolysis, glycogen, glucose, glucosamine, pentose phosphate pathway.
What are the two shuttles responsible for transferring reducing equivalents from glycolysis into the mitochondria? What is the major difference between these two?
The malate shuttle - involves a membrane transport system & produces 3 ATP
The Glycerol-3-phosphate shuttle - does not involve membrane transport systems & produces 2 ATP
Compare hexokinase to glucokinase.
Glucokinase has a specificity to glucose and is 3x larger than hexokinase. It is found in the liver/pancreas and is inhibited by fructose-6-phosphate.
Hexokinase are found elsewhere (muscle) and is inhibited by glucose-6-phosphate.
List three reasons for the importance of controlling glycolysis.
- Regulates ATP levels in cells
- Metabolite allocation
- Allows responsiveness to environment
What are the allosteric activators and inactivators of PFK-1?
Allosteric activators: AMP, ADP, fructose-2,6-bisphosphate
Allosteric inactivators: ATP, Citrate
How would high levels of ATP affect PFK-1?
PFK-1 activity would be lowered with high levels of ATP because it is an allosteric inactivator of that enzyme.
What affect does insulin have on PFK-1?
Insulin increases PFK-1 activity.
Reasoning: High levels of insulin correlate to high levels of blood glucose, so there is a metabolic need to break down glucose for storage or energy production.
