Glycolysis 101

STUDY NOTE: GLYCOLYSIS — EASY MNEMONICS FOR STEPS & ENZYMES

Introduction

Glycolysis is the initial pathway of carbohydrate metabolism.
In this pathway, glucose (6-carbon) is broken down into two molecules of pyruvate (3-carbon).
Because glucose is broken down, the pathway is called glyco-lysis.

• Occurs in the cytoplasm

• Does not require oxygen

• Consists of 10 enzyme-catalyzed steps

Overall Reaction

Glucose (6C) → 2 Pyruvate (3C)

PART 1: Mnemonic for INTERMEDIATE MOLECULES

Mnemonic Story

“Gross guys favor big butts, but good boys prefer pretty girls in pink pajamas.”

Each word represents a glycolysis intermediate.

Mnemonic Breakdown

Mnemonic Word	Molecule
Gross	Glucose
Guys	Glucose-6-phosphate
Favor	Fructose-6-phosphate
Big Butts	Fructose-1,6-bisphosphate
Good	Glyceraldehyde-3-phosphate (G3P)
Boys	1,3-Bisphosphoglycerate
Prefer	3-Phosphoglycerate
Pretty	2-Phosphoglycerate
Pink	Phosphoenolpyruvate (PEP)
Pajamas	Pyruvate

Important Concept

• Fructose-1,6-bisphosphate splits into:

  • Glyceraldehyde-3-phosphate (G3P)

  • Dihydroxyacetone phosphate (DHAP)

• Only G3P continues in glycolysis (DHAP is converted to G3P).

PART 2: Mnemonic for ENZYMES OF GLYCOLYSIS

Mnemonic Sentence

“Helen paints pictures along the training grounds, praying people enjoy paintings.”

Enzyme Breakdown

Mnemonic Letter	Enzyme	Reaction
H	Hexokinase	Glucose → Glucose-6-phosphate
P	Phosphoglucose isomerase	G6P → Fructose-6-phosphate
P	Phosphofructokinase-1 (PFK-1)	F6P → Fructose-1,6-bisphosphate
A	Aldolase	F-1,6-BP → G3P + DHAP
T	Triose phosphate isomerase	DHAP ↔ G3P
G	Glyceraldehyde-3-phosphate dehydrogenase	G3P → 1,3-BPG
B	Phosphoglycerate kinase	1,3-BPG → 3-PG
P	Phosphoglycerate mutase	3-PG → 2-PG
E	Enolase	2-PG → PEP
P	Pyruvate kinase	PEP → Pyruvate

Key High-Yield Points

• PFK-1 is the rate-limiting enzyme of glycolysis

• ATP is consumed in early steps (investment phase)

• ATP is produced in later steps (payoff phase)

• Net yield per glucose:

  • 2 ATP

  • 2 NADH

  • 2 Pyruvate

Clinical Relevance

• Increased glycolysis → cancer cells (Warburg effect)

• Pyruvate fate depends on oxygen:

  • Aerobic → Acetyl-CoA

  • Anaerobic → Lactate

• Enzyme deficiencies → hemolytic anemia (e.g., pyruvate kinase deficiency)