Glycolysis (Ben) Flashcards
What is the first reaction of glycolysis?
Substrate(s)?
Enzyme?
Product(s)?
Regulation?
Other important things to note?
Substrates: Glucose + ATP
Enzyme: Hexo-/Glucokinase
- Glucokinase (higher Km) in either liver or pancreatic b-cells as glucose level regulation mechanism
Products: Glucose-6-phosphate + ADP
Regulation: Allosteric via G-6-P
Notes: Irreversible + an important regulatory step
What is 2nd reaction of glycolysis… (the one including glucose-6-phosphate as its substrate) ?
Enzyme?
Product(s)?
Other important things to note?
- isomerization of G-6-P via…
Enzyme: Phosphohexose Isomerase
Product: Fructose-6-phosphate
Note: Reversible
What is the third reaction of glycolysis, acting upon fructose-6-phosphate?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Phosphorylation of fructose-6-phosphate using ATP via…
Enzyme: Phosphofructokinase
Product: Fructose 1,6 Bisphosphate + Phosphoric Acid
Notes:
- Irreversible + the so-called committed step of glycolysis
- Inhibited by normal intracellular [ATP]
- Inhibition relieved by 5’AMP due to ADP buildup
What is the 4th reaction of glycolysis, resulting in two isomeric products, only one of which continues to be used in glycolysis?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrate: Fructose 1,6-bisphosphate
Enzyme: Aldolase
Products: Dihydroxyacetone Phosphate + Glyceraldehyde-3-Phosphate
Notes: Reversible
What is the 6th reaction of glycolysis, acting on glyceraldehyde 3 phosphate?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrates: Glyceraldehyde-3-phosphate + NAD+ + Pi
Enzyme: Glyceraldehyde-3-phosphate dehydrogenase
Products: 1,3-Bisphosphoglycerate + NADH + H+
Note: Reversible
What is the fifth reaction of glycolysis, converting a 3 carbon substrate to its isomer?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrate: Dihydroxyacetone Phosphate
Enzyme: Triose Phosphate Isomerase
Product: Glyceraldehyde-3-phosphate
Note: Reversible
What is the seventh reaction of glycolysis + its first energetically productive step?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrates: 1,3-Bisphopshoglycerate + ADP
Enzyme: Phosphoglycerate Kinase
Products: 3-Phosphoglycerate + ATP
Note: Reversible + an example of substrate level phosphorylation
What is the 8th reaction of glycolysis, using 3-phosphoglycerate as its substrate?
Enzyme?
Product(s)?
Other important things to note?
Enzyme: Phosphoglycerate Mutase
Product: 2-Phosphoglycerate
Note: Reversible
What is the ninth (and second-to-last) reaction of glycolysis?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrate: 2-Phosphoglycerate
Enzyme: Enolase
Product: Phosphoenolpyruvate
Note: Reversible
What is the final reaction of glycolysis?
Substrate(s)?
Enzyme?
Product(s)?
Other important things to note?
Substrate: Phosphoenolpyruvate + ADP
Enzyme: Pyruvate Kinase
Product: Pyruvate + ATP
Note: IRREVERSIBLE + an example of substrate level phosphorylation
What is the point of phosphorylation in the 1st step of glycolysis?
Glucose-6-phosphate is not as easily transported out of the cell and this phosphorylation traps glucose in the cell in order for glycolysis to continue.
What is the important regulatory molecule formed in some cells by skipping/changing some steps of glycolysis?
What is its role and at what concentration is it found?
What enzyme catalyzes this different glycolytic route?
2,3-bisphosphoglycerate
- it binds to deoxy-hemoglobin in RBCs and decreases its O2 binding affinity
- it is found at about 5 mM in RBCs
- Bisphosphoglycerate mutase catalyzes the change of 1,3- to 2,3-
How does 2,3-bisphosphoglycerate re-enter glycolysis?
Via hydrolysis to 3-phosphoglycerate (and Pi) by the enzyme 2,3-bisphosphoglycerate phosphatase
What is the net reaction of glycolysis?
What is the pathway for anaerobic processing of pyruvate in humans (as in intense exercise)?
Substrates?
Enzymes/co-enzymes?
Products?
Lactic Acid Fermentation
Substrate: Pyruvate
Enzyme/Co-enzyme: Lactate Dehydrogenase + NADH + H+
Product: Lactate + NAD+
What is the overall net reaction of anaerobic glycolysis?
