What are the steps of glycolysis?

Author:

February 20th, 2023

WARNING. This is a VERY LONG answer because there are 10 steps to glycolysis.
Step 1. Phosphorylation of Glucose
##underbrace(“C”_6″H”_12″O”_6)_color(red)(“glucose”) + “ATP” stackrel(“hexokinase”)(→) “ADP” + underbrace(“C”_6″H”_11″O”_6″P”)_color(red)(“glucose 6-phosphate“)##
Step 2. Isomerization of Glucose 6-Phosphate
##underbrace(“C”_6″H”_11″O”_6″P”)_color(red)(“glucose 6-phosphate”) stackrel(“phosphoglucoisomerase”)( →) underbrace(“C”_6″H”_11″O”_6″P”)_color(red)(“fructose 6-phosphate”)##
Step 3. Phosphorylation of Fructose 6-Phosphate
## underbrace(“C”_6″H”_11″O”_6″P”)_color(red)(“fructose 6-phosphate”) + “ATP” stackrel(“phosphofructokinase”)(→) underbrace(“C”_6″H”_10″O”_6″P”_2) _color(red)(“fructose 1, 6-bisphosphate”) + “ADP”##
Step 4. Cleavage into 3-Carbon Fragments
##underbrace(“C”_6″H”_10″O”_6″P”_2) _color(red)(“fructose 1,6-bisphosphate”) stackrel(“aldolase”)(→) underbrace(“C”_3″H”_5″O”_3″P”)_color(red)(“dihydroxyacetone phosphate“) + underbrace(“C”_3″H”_5″O”_3″P”)_color(red)(“glyceraldehyde 3-phosphate“)##
Step 5. Tautomerization of the isomers
##underbrace(“C”_3″H”_5″O”_3″P”)_color(red)(“dihydroxyacetone phosphate”) stackrel(“triose phosphate isomerase”)(⇌) underbrace(“C”_3″H”_5″O”_3″P”)_color(red)(“glyceraldehyde 3-phosphate”)##
Glyceraldehyde 3-phosphate is on the direct pathway of glycolysis, but dihydroxyacetone phosphate is not.
The enzyme triose phosphate isomerase rapidly interconverts dihydroxyacetone phosphate into glyceraldehyde 3-phosphate so that it can be used to generate ##”ATP”##.
The net result for Steps 4 and 5 is
##underbrace(“C”_6″H”_10″O”_6″P”_2) _color(red)(“fructose 1,6-bisphosphate”) → underbrace(“2C”_3″H”_5″O”_3″P”)_color(red)(“glyceraldehyde 3-phosphate”)##
Step 6. Oxidative Phosphorylation
##underbrace(“2C”_3″H”_5″O”_3″P”)_color(red)(“glyceraldehyde 3-phosphate”) + “2NAD”^+ + “2HP”_i stackrel(“glyceraldehyde 3-phosphate dehydrogenase”)(→) underbrace(“2C”_3″H”_4″O”_4″P”_2)_color(red)(“1,3-bisphosphoglycerate”)+ “2NADH” + “2H”^+##
Step 7. Formation of ##”ATP”##
##underbrace(“2C”_3″H”_4″O”_4″P”_2)_color(red)(“1,3-bisphosphoglycerate”) + “2ADP” stackrel(“phosphoglycerokinase”)( →) underbrace(“2C”_3″H”_5″O”_4″P”)_color(red)(“3-phosphoglycerate”) + “2ATP”##
Step 8. Isomerization of 3-Phosphoglycerate
## underbrace(“2C”_3″H”_5″O”_4″P”)_color(red)(“3-phosphoglycerate”) stackrel(“phosphoglyceromutase”)(→) underbrace(“2C”_3″H”_5″O”_4″P”)_color(red)(“2-phosphoglycerate”)##
Step 9. Dehydration of 2-Phosphoglycerate
##underbrace(“2C”_3″H”_5″O”_4″P”)_color(red)(“2-phosphoglycerate”) stackrel(“enolase”) (→) underbrace(“2C”_3″H”_3″O”_3″P”)_color(red)(“2-phosphoenolpyruvate”) + “2H”_2″O”##
Step 10. Formation of ##”ATP”##
##underbrace(“2C”_3″H”_3″O”_3″P”)_color(red)(“2-phosphoenolpyruvate”) + “2ADP” stackrel(“pyruvate kinase”)( →) underbrace(“2C”_3″H”_3″O”_3)_color(red)(“pyruvate”) + “2ATP”##
Here is a summary of the metabolic pathway: