Question

MCAT Tutorial: Glycolysis

Answer 1

\({\bf{Overview:}}\)
- first stage in cellular respiration
- starts with a molecule of glucose C6H12O6
- results in the production of 2 pyruvate molecules, 2 ATP molecules (net, produces 4 but consumes 2 so net gain of 2), 2 NADH, as well as water and hydrogen ions

Answer 2

\({\bf{Reaction~1:}}\)
- uses 1 ATP molecule
- attaches the phosphate group to the glucose
- catalyzed by hexokinase (HK)
- produces glucose-6-phosphate (g6p)

\({\bf{Reaction~2:}}\)
- phosphoglucose isomerase converts g6p to fructose-6-phosphate

\({\bf{Reaction~3:}}\)
- phosphofructokinase (PFK) converts fructose-6-phosphate to fructose-1,6-biphosphate
- uses 1 ATP
- attaches the phosphate group to the glucose by-product

\({\bf{Reaction~4:}}\)
- fructose biphosphate aldolase splits molecule in two 3-carbon molecules

Answer 3

\({\bf{Reaction~5:}}\) (the diagram and the text are from diff. sources and thus are labelled a bit differently)
- conversion to 1,3-diphosphoglyceric acid via glyceraldehyde-3-phosphate
- produces 2 NADH (reaction occurs twice for each glucose molecule)

\({\bf{Reaction~6:}}\)
- produces 2 ATP via phosphoglycerate kinase
- produces 3-phosphoglyceric acid (called phosphoclycerate on the diagram)

\({\bf{Reaction~7:}}\)
- shifts the phosphate group to make 2-phosphoglyceric acid via phosphoglycerate mutase

\({\bf{Reaction~8:}}\)
- double bond formed via enolase
- forms PEP (phosphoenolpyruvic acid)

\({\bf{Reaction~9:}}\)
- phosphate group from PEP is moved to ADP
- produces 2 ATP
- net gain of 2 pyruvic acid molecules

Answer 4

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is the Princeton Review Anatomy Workbook, 4th ed.