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Metabolism: Krebs Cycle Simulation Playbook

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Before Starting the Simulation:
  • Ensure all VR headsets are charged and properly calibrated
  • Review safety guidelines for VR equipment use
  • Show students the essential VR gestures and controls
  • Plan your time: allocate 20 minutes for interaction and 10–15 minutes for reflection
During the Simulation:
  • Designate student helpers to assist their peers
  • Circulate throughout the classroom to support struggling students
  • Guide students to observe and document molecular changes during the Krebs Cycle
  • Prompt students to describe where inputs come from and where outputs go
Group Organization:
  • For classes with limited devices, form triads: one in VR, two observing/discussing
  • Rotate roles every 5–7 minutes
  • Provide printed diagrams of cellular structures for note-taking during observation
Troubleshooting Technical Issues:
  • Preload simulation and test each headset prior to class
  • Keep a backup tablet with 2D version of the lab in case of headset malfunction
  • Maintain clear VR boundaries and warn students about physical obstacles
Recommendations for Teachers
  • Before simulation:
    • Review with students what happened in glycolysis and the link reaction
  • During simulation:
    • Encourage students to track how each molecule (NAD⁺, FAD, ADP, Acetyl-CoA) is transformed
  • After simulation:
    • Ask students to build a diagram showing input/output of the Krebs cycle
1. Simulation Overview
  • Simulation title: Krebs Cycle – Cellular Respiration Part 3
  • Description: In this VR simulation, students complete the third phase of aerobic respiration. After entering the mitochondrion, they collect and assemble necessary molecules to launch the Krebs Cycle twice, observing production of ATP, NADH, FADH₂, and CO₂.
  • Simulation type: VR
  • Subject and age: Biology, Grades 9–12
  • Key topics:
    • Krebs (Citric Acid) Cycle
    • ATP generation via substrate-level phosphorylation
    • Role of electron carriers (NAD⁺, FAD)
    • Inputs: Acetyl-CoA, NAD⁺, FAD, ADP
    • Outputs: ATP, NADH, FADH₂, CO₂
    • 2. Key Simulation Milestones
    Time Simulation stage What happens before the action? What should be done? What happens after the action?
    00:00 Laboratory (Start) The student sees a microscope, the model organism, and the metabolic stage panel (first two stages colored, others grayed out). Click on the microscope to enter the cell. Scene changes to the cell interior.
    00:27 Cytoplasm The student sees major organelles. A pointer appears above the mitochondrion. Click on the mitochondrion to enter it. Scene changes to mitochondrial matrix.
    00:45 Mitochondrial matrix The student sees the Krebs cycle zone as a translucent green sphere labeled “Krebs Cycle.” Various components are scattered in the matrix. Collect and place into the green sphere:
    • 1 Acetyl-CoA
    • 3 NAD⁺
    • 1 FAD
    • 1 ADP
    • 1 Pi    		 A floating tablet appears with a “Start” button.
    02:42 Krebs Cycle activation All components are placed inside the green sphere. Click “Start” on the tablet. Animation plays showing the Krebs Cycle: production of CO₂, NADH, FADH₂, ATP, H⁺.
    02:56 Repetition phase Products appear; the student is prompted to repeat the cycle. 1. Repeat the collection and placement of all components as in step 3.
    2. Click “Finish” when prompted.    		 1. A “Finish” button appears.
    2. The student returns to the laboratory.
    04:43 Return to Lab Products have formed. At this stage, nothing needs to be done. The simulation returns to the lab. Krebs stage on the panel turns colored (completed).
    3. Theoretical Anchors (from the scene)
    • Krebs Cycle (also called the Citric Acid Cycle or Tricarboxylic Acid Cycle) occurs in the mitochondrial matrix. It is the third stage of aerobic cellular respiration, following glycolysis and the link reaction.
    • Inputs: Acetyl-CoA (a two-carbon molecule), NAD⁺ (nicotinamide adenine dinucleotide), FAD (flavin adenine dinucleotide), ADP (adenosine diphosphate), and inorganic phosphate (Pi).
    • Outputs: CO₂ (released as waste through decarboxylation), ATP (generated through substrate-level phosphorylation), and electron carriers NADH and FADH₂ (which transport high-energy electrons to the electron transport chain).
    • Each turn of the cycle processes one Acetyl-CoA molecule, producing 3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂.
    • The Krebs Cycle runs twice per glucose molecule. During glycolysis, each glucose produces two pyruvate molecules. Each pyruvate then generates one Acetyl-CoA—requiring two complete turns of the cycle.
    4. Reflection Questions
    • What happens to the carbon atoms from Acetyl-CoA?
    • Why are NADH and FADH₂ important after the Krebs Cycle?
    • How is ATP generated in the Krebs Cycle, and how does it differ from oxidative phosphorylation?
    • Why does the cycle run twice for each glucose molecule?
    5. Hard Skill Questions
    • List the inputs and outputs of one turn of the Krebs Cycle.
    • Explain the role of NAD⁺ and FAD in aerobic respiration.
    • How many ATP molecules are generated directly in the Krebs Cycle per glucose?
    • Where do the products of the Krebs Cycle go next?
    6. Attachments
    • Video walkthrough
    • Printable molecule matching cards
    • Google Form quiz for post-lab assessment
    • Diagram worksheet: label the inputs/outputs of the Krebs Cycle
    • QR code to access simulation on classroom headset