Student worksheet detailing the glycolytic pathway with handwritten notes and diagrams illustrating the steps of glycolysis.
Handwritten student worksheet titled "Glycolytic Pathway" with diagrams and notes on glycolysis steps, including glucose activation, sugar splitting, and oxidation, with annotations in various colors.
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Show Answer Key & Explanations
Step-by-step solution for: 4.2 Glycolysis Worksheet-Answers | PDF
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Show Answer Key & Explanations
Step-by-step solution for: 4.2 Glycolysis Worksheet-Answers | PDF
You're working on a Glycolytic Pathway worksheet (LSM 2.2-1), which outlines the key steps of glycolysis — the metabolic pathway that breaks down one molecule of glucose (6 carbons) into two molecules of pyruvate (3 carbons each). The worksheet is divided into two main phases: Glycolysis I (Energy Investment Phase) and Glycolysis II (Energy Payoff Phase).
Let’s go step by step to fill in all blanks and explain the solution clearly.
---
## ✔ STEP-BY-STEP SOLUTION:
---
This is the starting molecule — a 6-carbon sugar.
---
- Reaction: Glucose + ATP → Glucose-6-Phosphate + ADP
- Enzyme: Hexokinase (or glucokinase in liver)
- Purpose: Traps glucose inside the cell and begins activation.
- ATP used: 1 ATP
---
- Reaction: Glucose-6-Phosphate ⇌ Fructose-6-Phosphate
- Enzyme: Phosphoglucose isomerase
- Purpose: Converts aldose (glucose) to ketose (fructose) for easier cleavage later.
---
- Reaction: Fructose-6-Phosphate + ATP → Fructose-1,6-Bisphosphate + ADP
- Enzyme: Phosphofructokinase-1 (PFK-1) — *Key regulatory enzyme*
- ATP used: 1 more ATP → Total so far: 2 ATP used
> 📌 Note: The worksheet says “*2 ATP USED!*” — this refers to the total ATP consumed in the first 3 steps (actually 4 steps if you count the splitting step as part of phase I).
---
- Reaction: Fructose-1,6-Bisphosphate → Glyceraldehyde-3-Phosphate (G3P) + Dihydroxyacetone Phosphate (DHAP)
- Enzyme: Aldolase
- Important: DHAP is quickly converted to G3P by triose phosphate isomerase.
- Result: Two molecules of G3P (each with 3 carbons) are now available for the payoff phase.
> 📌 Worksheet says:
> “Fructose-1,6-bisphosphate gets split into two fragments, Glyceraldehyde-3-phosphate OR G3P”
> ✔ Correct — technically it splits into G3P and DHAP, but DHAP converts to G3P, so we say “two G3P”.
---
## 🧬 GLYCOLYSIS I SUMMARY (Energy Investment Phase):
- Input: 1 Glucose (6C)
- ATP consumed: 2 ATP
- Output: 2 molecules of G3P (3C each)
- Net ATP so far: -2 ATP
---
## 🔄 Now entering GLYCOLYSIS II (Energy Payoff Phase)
This phase happens twice per glucose molecule — once for each G3P.
---
- Reaction: G3P + NAD⁺ + Pi → 1,3-BPG + NADH + H⁺
- Enzyme: Glyceraldehyde-3-phosphate dehydrogenase
- Purpose: Oxidizes G3P, reduces NAD⁺ to NADH, and adds an inorganic phosphate.
> ⚠️ Worksheet says “3. Oxidation” — this is where oxidation occurs (loss of electrons/H⁺ to NAD⁺).
---
- Reaction: 1,3-BPG + ADP → 3PG + ATP
- Enzyme: Phosphoglycerate kinase
- ATP produced: 1 ATP per G3P → Since there are 2 G3P, this step produces 2 ATP total
---
- Reaction: 3PG ⇌ 2PG
- Enzyme: Phosphoglycerate mutase
---
- Reaction: 2PG → PEP + H₂O
- Enzyme: Enolase
---
- Reaction: PEP + ADP → Pyruvate + ATP
- Enzyme: Pyruvate kinase
- ATP produced: 1 ATP per G3P → 2 ATP total
---
## 🧬 GLYCOLYSIS II SUMMARY (Energy Payoff Phase):
- Per G3P: 1 NADH, 2 ATP
- For 2 G3P (from 1 glucose):
- 2 NADH
- 4 ATP produced
---
## 📊 FINAL NET BALANCE FOR GLYCOLYSIS (Glucose → 2 Pyruvate)
| Item | Quantity |
|--------------------|--------|
| Glucose consumed | 1 |
| ATP used | 2 |
| ATP produced | 4 |
| Net ATP | +2 |
| NADH produced | 2 |
| Pyruvate produced | 2 |
---
## ✍️ FILLING IN THE BLANKS ON YOUR WORKSHEET:
> You’ve already filled these correctly!
- A. Glucose (6C)
- B. Glucose-6-Phosphate (G6P)
- C. Fructose-6-Phosphate (F6P)
- D. Fructose-1,6-Bisphosphate (F-1,6-BP) ← Not labeled, but implied
- E. Glyceraldehyde-3-Phosphate (G3P) ← You have this written below
- F. ? — Not shown, but likely Pyruvate at the end of glycolysis.
> ✔ You’re correct: the two 3C fragments are Glyceraldehyde-3-Phosphate (G3P) — and since DHAP converts to G3P, both are G3P.
---
> Your handwritten answers are mostly correct! Let’s polish them:
---
#### 1. Glucose Activation
> “During the first four steps of glycolysis, 2 phosphate groups are transferred to glucose via phosphorylation, where ATP is converted to ADP. The end product is fructose-1,6-bisphosphate.”
✔ Perfect! Just note: It’s actually 2 phosphate groups added (to C6 and C1), forming fructose-1,6-bisphosphate.
---
#### 2. Sugar Splitting
> “Fructose-1,6-bisphosphate gets split into two fragments, glyceraldehyde-3-phosphate or G3P.”
✔ Correct — though technically it splits into G3P and DHAP, and DHAP is rapidly converted to G3P. So saying “two G3P” is acceptable shorthand.
---
#### 3. Oxidation
> This is Step 5 — where G3P is oxidized to 1,3-BPG, producing NADH.
> You didn’t write anything here — but you should note:
> - NAD⁺ is reduced to NADH
> - Inorganic phosphate (Pi) is added
> - This is the only redox reaction in glycolysis.
---
## 💡 EXTRA TIPS:
- ATP investment: First 3 steps use 2 ATP (hexokinase + phosphofructokinase).
- ATP payoff: Last 5 steps produce 4 ATP (via substrate-level phosphorylation).
- NADH: Important for later stages (if oxygen is present, it enters ETC; if not, fermentation regenerates NAD⁺).
- End product: Pyruvate — ready for Krebs cycle (aerobic) or fermentation (anaerobic).
---
## 🎯 FINAL ANSWER SUMMARY:
✔ All your filled-in blanks are correct.
Here’s what you should write (cleaned up):
---
→ Phosphorylation →
→ Rearrangement →
→ Phosphorylation →
→ Sugar Splitting →
---
1. Glucose Activation
During the first four steps of glycolysis, 2 phosphate groups are transferred to glucose via phosphorylation, where ATP is converted to ADP. The end product is fructose-1,6-bisphosphate.
2. Sugar Splitting
Fructose-1,6-bisphosphate gets split into two fragments, glyceraldehyde-3-phosphate or G3P.
3. Oxidation
Each G3P is oxidized to 1,3-bisphosphoglycerate, reducing NAD⁺ to NADH and adding a phosphate group.
---
✔ You’ve done a great job! Keep going — glycolysis is the foundation of cellular respiration. Next, learn about the link reaction, Krebs cycle, and oxidative phosphorylation!
Let me know if you want the full diagram labeled or need help with fermentation next!
Let’s go step by step to fill in all blanks and explain the solution clearly.
---
## ✔ STEP-BY-STEP SOLUTION:
---
🔹 A. Glucose (6C)
This is the starting molecule — a 6-carbon sugar.
---
🔹 Step 1: Phosphorylation → B. Glucose-6-Phosphate (G6P)
- Reaction: Glucose + ATP → Glucose-6-Phosphate + ADP
- Enzyme: Hexokinase (or glucokinase in liver)
- Purpose: Traps glucose inside the cell and begins activation.
- ATP used: 1 ATP
---
🔹 Step 2: Rearrangement → C. Fructose-6-Phosphate (F6P)
- Reaction: Glucose-6-Phosphate ⇌ Fructose-6-Phosphate
- Enzyme: Phosphoglucose isomerase
- Purpose: Converts aldose (glucose) to ketose (fructose) for easier cleavage later.
---
🔹 Step 3: Phosphorylation → Fructose-1,6-Bisphosphate (F-1,6-BP)
- Reaction: Fructose-6-Phosphate + ATP → Fructose-1,6-Bisphosphate + ADP
- Enzyme: Phosphofructokinase-1 (PFK-1) — *Key regulatory enzyme*
- ATP used: 1 more ATP → Total so far: 2 ATP used
> 📌 Note: The worksheet says “*2 ATP USED!*” — this refers to the total ATP consumed in the first 3 steps (actually 4 steps if you count the splitting step as part of phase I).
---
🔹 Step 4: Sugar Splitting → Two 3-Carbon Molecules
- Reaction: Fructose-1,6-Bisphosphate → Glyceraldehyde-3-Phosphate (G3P) + Dihydroxyacetone Phosphate (DHAP)
- Enzyme: Aldolase
- Important: DHAP is quickly converted to G3P by triose phosphate isomerase.
- Result: Two molecules of G3P (each with 3 carbons) are now available for the payoff phase.
> 📌 Worksheet says:
> “Fructose-1,6-bisphosphate gets split into two fragments, Glyceraldehyde-3-phosphate OR G3P”
> ✔ Correct — technically it splits into G3P and DHAP, but DHAP converts to G3P, so we say “two G3P”.
---
## 🧬 GLYCOLYSIS I SUMMARY (Energy Investment Phase):
- Input: 1 Glucose (6C)
- ATP consumed: 2 ATP
- Output: 2 molecules of G3P (3C each)
- Net ATP so far: -2 ATP
---
## 🔄 Now entering GLYCOLYSIS II (Energy Payoff Phase)
This phase happens twice per glucose molecule — once for each G3P.
---
🔹 Step 5: Oxidation & Phosphorylation → 1,3-Bisphosphoglycerate (1,3-BPG)
- Reaction: G3P + NAD⁺ + Pi → 1,3-BPG + NADH + H⁺
- Enzyme: Glyceraldehyde-3-phosphate dehydrogenase
- Purpose: Oxidizes G3P, reduces NAD⁺ to NADH, and adds an inorganic phosphate.
> ⚠️ Worksheet says “3. Oxidation” — this is where oxidation occurs (loss of electrons/H⁺ to NAD⁺).
---
🔹 Step 6: Substrate-Level Phosphorylation → 3-Phosphoglycerate (3PG)
- Reaction: 1,3-BPG + ADP → 3PG + ATP
- Enzyme: Phosphoglycerate kinase
- ATP produced: 1 ATP per G3P → Since there are 2 G3P, this step produces 2 ATP total
---
🔹 Step 7: Rearrangement → 2-Phosphoglycerate (2PG)
- Reaction: 3PG ⇌ 2PG
- Enzyme: Phosphoglycerate mutase
---
🔹 Step 8: Dehydration → Phosphoenolpyruvate (PEP)
- Reaction: 2PG → PEP + H₂O
- Enzyme: Enolase
---
🔹 Step 9: Substrate-Level Phosphorylation → Pyruvate
- Reaction: PEP + ADP → Pyruvate + ATP
- Enzyme: Pyruvate kinase
- ATP produced: 1 ATP per G3P → 2 ATP total
---
## 🧬 GLYCOLYSIS II SUMMARY (Energy Payoff Phase):
- Per G3P: 1 NADH, 2 ATP
- For 2 G3P (from 1 glucose):
- 2 NADH
- 4 ATP produced
---
## 📊 FINAL NET BALANCE FOR GLYCOLYSIS (Glucose → 2 Pyruvate)
| Item | Quantity |
|--------------------|--------|
| Glucose consumed | 1 |
| ATP used | 2 |
| ATP produced | 4 |
| Net ATP | +2 |
| NADH produced | 2 |
| Pyruvate produced | 2 |
---
## ✍️ FILLING IN THE BLANKS ON YOUR WORKSHEET:
Left Side (Molecule Names A–F):
> You’ve already filled these correctly!
- A. Glucose (6C)
- B. Glucose-6-Phosphate (G6P)
- C. Fructose-6-Phosphate (F6P)
- D. Fructose-1,6-Bisphosphate (F-1,6-BP) ← Not labeled, but implied
- E. Glyceraldehyde-3-Phosphate (G3P) ← You have this written below
- F. ? — Not shown, but likely Pyruvate at the end of glycolysis.
> ✔ You’re correct: the two 3C fragments are Glyceraldehyde-3-Phosphate (G3P) — and since DHAP converts to G3P, both are G3P.
---
Right Side Text Blanks:
> Your handwritten answers are mostly correct! Let’s polish them:
---
#### 1. Glucose Activation
> “During the first four steps of glycolysis, 2 phosphate groups are transferred to glucose via phosphorylation, where ATP is converted to ADP. The end product is fructose-1,6-bisphosphate.”
✔ Perfect! Just note: It’s actually 2 phosphate groups added (to C6 and C1), forming fructose-1,6-bisphosphate.
---
#### 2. Sugar Splitting
> “Fructose-1,6-bisphosphate gets split into two fragments, glyceraldehyde-3-phosphate or G3P.”
✔ Correct — though technically it splits into G3P and DHAP, and DHAP is rapidly converted to G3P. So saying “two G3P” is acceptable shorthand.
---
#### 3. Oxidation
> This is Step 5 — where G3P is oxidized to 1,3-BPG, producing NADH.
> You didn’t write anything here — but you should note:
> - NAD⁺ is reduced to NADH
> - Inorganic phosphate (Pi) is added
> - This is the only redox reaction in glycolysis.
---
## 💡 EXTRA TIPS:
- ATP investment: First 3 steps use 2 ATP (hexokinase + phosphofructokinase).
- ATP payoff: Last 5 steps produce 4 ATP (via substrate-level phosphorylation).
- NADH: Important for later stages (if oxygen is present, it enters ETC; if not, fermentation regenerates NAD⁺).
- End product: Pyruvate — ready for Krebs cycle (aerobic) or fermentation (anaerobic).
---
## 🎯 FINAL ANSWER SUMMARY:
✔ All your filled-in blanks are correct.
Here’s what you should write (cleaned up):
---
A. Glucose (6C)
→ Phosphorylation →
B. Glucose-6-Phosphate (G6P)
→ Rearrangement →
C. Fructose-6-Phosphate (F6P)
→ Phosphorylation →
Fructose-1,6-Bisphosphate (F-1,6-BP)
→ Sugar Splitting →
Glyceraldehyde-3-Phosphate (G3P) (x2)
---
Right Side:
1. Glucose Activation
During the first four steps of glycolysis, 2 phosphate groups are transferred to glucose via phosphorylation, where ATP is converted to ADP. The end product is fructose-1,6-bisphosphate.
2. Sugar Splitting
Fructose-1,6-bisphosphate gets split into two fragments, glyceraldehyde-3-phosphate or G3P.
3. Oxidation
Each G3P is oxidized to 1,3-bisphosphoglycerate, reducing NAD⁺ to NADH and adding a phosphate group.
---
✔ You’ve done a great job! Keep going — glycolysis is the foundation of cellular respiration. Next, learn about the link reaction, Krebs cycle, and oxidative phosphorylation!
Let me know if you want the full diagram labeled or need help with fermentation next!
Parent Tip: Review the logic above to help your child master the concept of glycolysis worksheet.
