1
2
3
4
5
6
7
8
9
10
🎯 Score
0
⭐ High Score
0
🔥 Streak
0
Stage 1: Glucose Activation 🚀
The First Investment - Adding a Phosphate Group
Glucose (C₆H₁₂O₆)
C
C
C
C
C
O
O
O
O
O
O
Starting molecule
Free glucose in cell
Free glucose in cell
Hexokinase
Glucose-6-Phosphate
C
C
C
C
C
O
O
O
O
O
O
P
Activated molecule
Trapped in cell ⚡
Trapped in cell ⚡
💰 Energy Investment: Uses 1 ATP → ADP + Pi
🎮 GAME ANALOGY
Theme park ticket activation! You pay $1 (ATP) to stamp your ticket (phosphate) so you can't lose it outside the park. Now you're trapped inside and ready for rides!
🎯 Key Points:
- ✅ Traps glucose inside cell (phosphate can't cross membrane)
- ✅ Investment: 1 ATP
- ✅ Enzyme: Hexokinase
- ✅ Rate-limiting step
📝 Challenge Questions - Stage 1
Q1: Why does the cell "spend" ATP at the start?
Q2: What if hexokinase was missing?
Q3: The phosphate group is like...
Stage 2: The Isomerization Shuffle 🔄
Rearranging Atoms - Preparing for the Big Split!
Glucose-6-Phosphate (Aldose)
C1
C2
C3
C4
C5
O
O
O
P
6-membered ring
Carbonyl at C1
Carbonyl at C1
Phosphoglucose Isomerase
Fructose-6-Phosphate (Ketose)
C2
C3
C4
C5
C=O
O
O
O
P
5-membered ring + tail
Carbonyl at C2
Carbonyl at C2
🎮 PARTY SETUP!
Same furniture, but you rearrange to make space for dancing. The carbonyl group moves from C1 to C2 - crucial for the upcoming split!
📝 Challenge Questions - Stage 2
Q1: Why is isomerization necessary?
Q2: What does "isomerization" mean?
Q3: Difference between G6P and F6P?
Stage 3: The Power Boost ⚡
Second ATP Investment - The Commitment Step!
Fructose-6-Phosphate
C2
C3
C4
C5
C=O
O
O
O
P
ONE phosphate
At carbon #6
At carbon #6
Phosphofructokinase-1 (PFK-1)
COMMITMENT ENZYME
Fructose-1,6-Bisphosphate
C2
C3
C4
C5
C=O
O
O
O
P
P
TWO phosphates!
At #1 AND #6
At #1 AND #6
💰 Energy Investment - Second Payment
ATP
⚡→
ADP + Pi
Total invested: 2 ATP
🎯 What is a "Commitment Step"?
- ⚠️ Irreversible - Cannot go backward
- ⚠️ Rate-limiting - Most controlled step
- ⚠️ Point of no return - Glycolysis MUST finish
🎮 FINAL BOSS UPGRADE!
You're about to face the boss! You spend gold (2nd ATP) to activate "Mega Weapon". PFK-1 is the shopkeeper who controls this upgrade. No refund = you're committed to the fight!
📝 Challenge Questions - Stage 3
Q1: Why is this the "Commitment Step"?
Q2: What makes PFK-1 special?
Q3: If PFK-1 was blocked?
Stage 4: The Great Split 💥
From 6-Carbon to Two 3-Carbon Molecules!
Fructose-1,6-Bisphosphate
C2
C3
P
C4
C=O
O
O
C5
P
C6
6 CARBONS
Ready to cleave!
Ready to cleave!
Aldolase
"The Splitter"
Glyceraldehyde-3-P (G3P)
P
C1
C2
C3
O
O
O
3-Carbon
Will become G3P
Will become G3P
Dihydroxyacetone-P (DHAP)
P
C4
C5
C6
O
O
O
3-Carbon
Will convert to G3P
Will convert to G3P
⚡ Energy Status: No gain/loss
Just breaking in half - like splitting a candy bar!
🍫 SPLITTING A CANDY BAR!
You have a 6-piece candy bar (F1,6BP). You break it exactly in half → two 3-piece halves (G3P & DHAP). Same total pieces, just separated!
🎯 Key Points:
- ✅ C-C bond broken between C3 and C4
- ✅ Creates TWO 3-carbon molecules
- ✅ DHAP must convert to G3P (next step)
- ✅ No energy change - just cleavage
📝 Challenge Questions - Stage 4
Q1: What happens in the aldolase reaction?
Q2: Where is the bond broken?
Q3: Energy outcome of this step?
Stage 5: Twin Conversion 🔄→⚡
DHAP → G3P: Getting Two for the Price of One!
Dihydroxyacetone-P (DHAP)
P
C=O
CHOH
CH₂OH
O
O
O
DHAP
Ketone structure
Ketone structure
Triose Phosphate Isomerase
"The Converter"
Glyceraldehyde-3-P (G3P)
P
CHO
HC-OH
CH₂OH
O
O
O
G3P
Aldehyde structure
Aldehyde structure
⚡ Energy Status: Near equilibrium
Very fast reaction - both DHAP and G3P are present
🎯 CRITICAL INSIGHT
Now we have TWO G3P molecules! Even though glycolysis splits F1,6BP into one G3P and one DHAP, DHAP quickly converts to G3P. So effectively, we have TWO identical 3-carbon molecules moving forward. This means everything from now on happens TWICE per glucose!
🎯 TWO FOR ONE DEAL!
You split a candy bar and get one milk chocolate half (G3P) and one dark chocolate half (DHAP).
But you only like milk chocolate! So you trade the dark piece with a friend who converts it to milk chocolate.
Now you have two identical pieces!
🎯 Key Points:
- ✅ DHAP and G3P are isomers
- ✅ DHAP converts to G3P (not much G3P → DHAP)
- ✅ Reaction is fast and reversible
- ✅ Result: Two G3P molecules per glucose!
📝 Challenge Questions - Stage 5
Q1: What is the outcome of this step?
Q2: Why is this conversion important?
Q3: How many G3P molecules per glucose?
🏆 You've Completed Stages 1-5!
0
Points Earned
150
Max Points
0%
Accuracy
🎯 What You've Achieved:
- ✅ Stage 1: Activated glucose with hexokinase (1 ATP spent)
- ✅ Stage 2: Rearranged to fructose-6-phosphate via isomerization
- ✅ Stage 3: Committed with PFK-1 (2nd ATP invested = 2 total)
- ✅ Stage 4: Split the 6-carbon molecule into two 3-carbon pieces
- ✅ Stage 5: Converted DHAP → G3P (now 2 identical G3P per glucose)
💡 Ready for the Energy Payoff!
The investment phase is complete. Now you'll harvest energy and produce ATP!
The investment phase is complete. Now you'll harvest energy and produce ATP!
Stage 6: Energy Harvest Begins ⚡
G3P → 1,3-BPG: Oxidation & First Energy Capture!
Glyceraldehyde-3-P (G3P)
P
CHO
HC-OH
CH₂OH
O
O
O
3-Carbon Aldehyde
Ready to oxidize
Ready to oxidize
Glyceraldehyde-3-P Dehydrogenase
1,3-Bisphosphoglycerate
P
C=O
HC-OH
CH₂OH
P
O
O
NEW PHOSPHATE!
High-energy bond
High-energy bond
+1
NADH + H⁺
→
NAD⁺ Used
🎉 FIRST ENERGY PAYOFF!
- ✅ Oxidation: G3P loses electrons (aldehyde → carboxylic acid)
- ✅ Phosphate added: Creates high-energy acyl phosphate bond
- ✅ NAD⁺ reduced: To NADH + H⁺ (electron carrier for later!)
🔋 CHARGING A BATTERY!
You're cracking open a glow stick (G3P). The chemical reaction releases light energy (NADH) and creates a high-energy intermediate (1,3-BPG)
that you'll use later. The NADH is like storing that energy in a rechargeable battery for the cell!
🎯 Key Points:
- ✅ Inorganic phosphate (Pi) added - NOT from ATP!
- ✅ Creates high-energy acyl phosphate bond
- ✅ Produces NADH + H⁺ (energy carrier)
- ✅ This happens TWICE per glucose (2 G3P molecules)
📝 Challenge Questions - Stage 6
Q1: What is the energy product of this step?
Q2: Where does the new phosphate come from?
Q3: How many NADH per glucose?
Stage 7: First ATP Payday 💰
1,3-BPG → 3-PG: Substrate-Level Phosphorylation #1!
1,3-Bisphosphoglycerate
P
C=O
HC-OH
CH₂OH
P
O
O
HIGH ENERGY!
Acyl phosphate bond
Acyl phosphate bond
Phosphoglycerate Kinase
"The Payday"
3-Phosphoglycerate
P
C=O
HC-OH
CH₂OH
O
O
O
O
Lower energy
Phosphate transferred to ADP
Phosphate transferred to ADP
+1
ATP Generated
→
ADP + Pi
🎉 SUBSTRATE-LEVEL PHOSPHORYLATION!
- ✅ High-energy phosphate bond transfers directly to ADP
- ✅ Makes ATP without oxygen (anaerobic!)
- ✅ Happens TWICE per glucose = 2 ATP total
- ✅ Recoups the 2 ATP invested earlier!
🏦 CASHING A CHECK!
You have a high-energy cashier's check (1,3-BPG). You go to the bank (phosphoglycerate kinase) and transfer that energy into cash (ATP).
The check becomes regular paper (3-PG) after you cash it. Since you had two checks, you get 2 cash payments!
🎯 Key Points:
- ✅ Substrate-level phosphorylation: Direct phosphate transfer
- ✅ No oxygen needed - can happen anaerobically
- ✅ Each G3P → 1 ATP, so 2 ATP per glucose
- ✅ This breaks even with the 2 ATP invested
📝 Challenge Questions - Stage 7
Q1: What is substrate-level phosphorylation?
Q2: How many ATP from this step per glucose?
Q3: Why is this called "payday"?
Stage 8: Phosphate Shuffle 🎲
3-PG → 2-PG: Preparing for the Final Payoff!
3-Phosphoglycerate
P
C=O
HC-OH
CH₂OH
O
O
O
O
Phosphate on C3
(end of molecule)
(end of molecule)
Phosphoglycerate Mutase
"The Shuffler"
2-Phosphoglycerate
C=O
HC-OH
CH₂OH
P
O
O
O
O
Phosphate moved to C2
(middle position)
(middle position)
⚡ Energy Status: No net gain/loss
Very fast reaction - both DHAP and G3P are present
🔧 ADJUSTING THE ENGINE!
You're fine-tuning an engine before the final race. You move a spark plug from the back (C3) to the center (C2)
to get better ignition. Same parts, better position for maximum power output later!
🎯 Key Points:
- ✅ Rearrangement only: Phosphate moves from C3 to C2
- ✅ Mutase enzyme: Moves functional groups within molecule
- ✅ Prepares molecule for dehydration (next step)
- ✅ Near equilibrium - very fast reaction
📝 Challenge Questions - Stage 8
Q1: What happens in this step?
Q2: Why is this shuffle necessary?
Q3: Energy change?
Stage 9: Power Concentration 💧→⚡
2-PG → Phosphoenolpyruvate (PEP): Removing Water to Store Energy!
2-Phosphoglycerate
C=O
HC-OH
CH₂OH
P
O
O
O
O
Low energy
Phosphate-ester bond
Phosphate-ester bond
Enolase
"The Dehydrator"
Phosphoenolpyruvate (PEP)
C=O
C=C
CH₂
P
O
O
O
VERY HIGH ENERGY!
Enol phosphate bond
Enol phosphate bond
⚡ Energy Status: MASSIVE ENERGY GAIN
Removing water concentrates energy into the phosphate bond, making it the highest energy bond in glycolysis!
💧 WATER REMOVED (DEHYDRATION)
- ✅ 2-PG loses an -OH group and an -H atom = H₂O removed
- ✅ Creates enol phosphate bond - extremely unstable/high-energy
- ✅ This is the most energetic phosphate bond in the pathway
- ✅ Perfect for making ATP in the final step!
🔥 CONCENTRATING FUEL!
You have dilute juice (2-PG) and you remove water to make super-concentrated syrup (PEP). The same amount of "stuff" is there,
but now it's packed with much more potential energy! This concentrated fuel will power the final big ATP generation.
🎯 Key Points:
- ✅ Dehydration: Removes H₂O from molecule
- ✅ Creates enol phosphate - highest energy bond
- ✅ Catalyzed by enolase (needs Mg²⁺)
- ✅ Irreversible under cellular conditions
📝 Challenge Questions - Stage 9
Q1: What makes PEP special?
Q2: What is removed in this step?
Q3: Why is dehydration important here?
Stage 10: Grand Finale 🏆
PEP → Pyruvate: The Big ATP Payoff!
Phosphoenolpyruvate (PEP)
C=O
C=C
CH₂
P
O
O
O
HIGHEST ENERGY!
Ready to transfer
Ready to transfer
Pyruvate Kinase
"The Jackpot"
Pyruvate
C=O
C=O
CH₃
O
O
O
O
FINAL PRODUCT!
3-Carbon pyruvate
3-Carbon pyruvate
+2
ATP Generated
→
ADP + Pi
🎉 SUBSTRATE-LEVEL PHOSPHORYLATION #2!
The highest energy phosphate bond in glycolysis transfers to ADP. This is the most exergonic reaction in the pathway -
so much energy released that it's irreversible! Since we have 2 PEP molecules, we get 2 ATP here → Total: 4 ATP per glucose!
🎰 JACKPOT WIN!
You have two lottery tickets with the highest possible prize (PEP). You go to the lottery office (pyruvate kinase) and cash them in.
Each ticket gives you $2 (ATP). Since you have two tickets, you win $4 total! The office keeps the used tickets (pyruvate).
🎯 Key Points:
- ✅ Irreversible reaction - huge energy release
- ✅ Uses the highest-energy phosphate bond in glycolysis
- ✅ Produces 2 ATP per glucose (1 per PEP)
- ✅ Total ATP: 4 produced - 2 invested = NET GAIN of 2 ATP!
📝 Challenge Questions - Stage 10
Q1: Why is this reaction irreversible?
Q2: Net ATP gain per glucose?
Q3: What happens to the phosphate from PEP?
🏆 Glycolysis Complete - All 10 Stages!
4
ATP Produced
-2
ATP Invested
+2
Net ATP
2
NADH Produced
0
Total Score
🎯 What You've Achieved:
- ✅ Stages 1-3 (Investment): Spent 2 ATP to activate and trap glucose
- ✅ Stage 4: Split 6C molecule → two 3C molecules
- ✅ Stage 5: Converted DHAP → G3P (now 2 identical molecules)
- ✅ Stage 6: Oxidized G3P → captured 2 NADH + H⁺
- ✅ Stage 7: First ATP payoff! 2 ATP produced (break even)
- ✅ Stage 8: Rearranged phosphate for final payoff
- ✅ Stage 9: Removed water → concentrated energy into PEP
- ✅ Stage 10: Jackpot! 2 more ATP = +2 net ATP per glucose!
🚀 Next Steps: The 2 NADH can produce 5-6 more ATP in mitochondria (cellular respiration) - that's where the real energy harvest begins!
