Oxidative Phosphorylation Tournament
Two onboarding diagrams place oxidative phosphorylation inside aerobic respiration. Then eight MCAT-DoK rounds: define Δp, walk Boyer's binding-change mechanism, predict oligomycin's effect on O2 uptake, compute the H+/ATP cost, list everything that raises O2 demand, and reason about thermogenin's regulated proton leak in brown adipose tissue.
Where the Formation of ATP by chemiosmotic coupling fits in Aerobic respiration & respiratory electron transport
Oxidative phosphorylation is the second half of the cellular-respiration story: the proton gradient built by the ETC is converted into ATP at the F1F0 ATP synthase rotor. To enter the tournament, click the highlighted Formation of ATP by chemiosmotic coupling box.
Click the highlighted Formation of ATP by chemiosmotic coupling box to continue.
What this tournament tests
Each task maps to a distinct MCAT cognitive demand. The first two orient you in the broader topology; the next eight test the high-yield mechanism, regulation, sequence and quantitative reasoning that consistently appear on test day.
The Bigger Picture
Locate ATP synthase inside aerobic respiration on the Reactome parent map.
Whole-Pathway Overview
Pan and zoom the WikiPathways oxidative-phosphorylation figure before you play.
Fill in the Blank
Define the proton motive force (Δp) and its electrical + chemical components.
Disruptor
Predict oligomycin's effect on O2 uptake and the proton gradient.
Sequence Ordering
Walk Boyer's binding-change cycle: Loose -> Tight -> Open at the F1 head.
Match the Pairs
Pair F0/F1 components with their structural and catalytic roles.
Numeric Input
Compute the H+ cost per cytosolic ATP including the ADP/ATP translocase tax.
Select All That Apply
Identify everything that raises mitochondrial O2 consumption.
Odd One Out
Spot the freely-permeable substrate among the carrier-dependent ones.
Brown Fat Physiology
Reason about thermogenin (UCP1) and non-shivering thermogenesis.
Public leaderboard
Your score posts to a global, persistent leaderboard scored by points first, time as tiebreaker.
Oxidative phosphorylation in 60 seconds
Chemiosmosis is Mitchell's big idea: the ETC pumps H+ out, the F1F0 ATP synthase lets H+ back in, and the flow torques a rotor that mechanically forces ADP + Pi -> ATP at the F1 catalytic head. The driving force is the proton motive force, Δp = ΔΨ - 2.303(RT/F)ΔpH (electrical + chemical).
Boyer's binding-change mechanism: the asymmetric γ-subunit, rotated by the c-ring, walks each β-subunit through three states - Loose (binds ADP + Pi), Tight (catalyzes ATP), Open (releases ATP). Each ATP costs roughly 4 H+ once the ADP/ATP translocase + Pi import are paid for.
Inhibitors and uncouplers expose the logic: oligomycin plugs F0 -> gradient inflates -> ETC back-pressures -> O2 uptake falls. DNP and thermogenin (UCP1) short the gradient -> ETC sprints, but no ATP forms - heat instead.
The four states of mitochondrial respiration (1: rest; 2: substrate, no ADP; 3: ATP-making peak; 4: ADP-depleted) map directly to the canonical O2-uptake trace MCAT is fond of using.
FAQ
What is the P/O ratio?
P/O = ATP produced per atom of O2 consumed (i.e. per pair of electrons). Canonical numbers: ~2.5 for NADH, ~1.5 for FADH2, accounting for the H+ tax of moving ATP out via ANT and Pi in via PiC.
Why does brown adipose tissue waste energy as heat?
Newborns and hibernators rely on UCP1 (thermogenin) - a regulated proton channel that lets H+ short-circuit ATP synthase. The ETC keeps running at full speed, but its energy is dissipated as heat. This is non-shivering thermogenesis.
Do I need an account to play?
No. The tournament is fully public. You get a randomized handle and your score posts to the public leaderboard at the bottom of this page.
Keep going
Where the proton gradient OxPhos consumes is built. Rotenone, antimycin, cyanide and the Q-cycle.
TCA enzymology and NADH/FADH2/GTP/CO2 stoichiometry - the input deck for OxPhos.
Overview diagram: Reactome Pathway R-HSA-1428517, licensed CC BY 4.0.