{"format":"molecular-machines.cards","version":1,"updated":"2026-10-12","decks":[{"machine":"atp-synthase","name":"ATP synthase","count":10,"url":"/learn/cards/atp-synthase.json"}],"cards":[{"id":"atp-synthase-energy-source","machine":"atp-synthase","kind":"qa","prompt":"ATP synthase sits in the inner membrane of your mitochondria. Pumps in that membrane push protons to one side. What does ATP synthase use to make ATP?","answer":"The flow of protons back across the membrane.","explanation":"Protons flow back through it like water through a turbine below a dam.","section":"summary","topic":"purpose","sources":["machine:energy","machine:where","story:summary"],"difficulty":1,"url":"/machines/atp-synthase#summary","cites":[{"source":"machine:energy","machine":"atp-synthase","label":"Summary","section":"summary"},{"source":"machine:where","machine":"atp-synthase","label":"Summary","section":"summary"},{"source":"story:summary","machine":"atp-synthase","label":"Big picture","section":"story"}]},{"id":"atp-synthase-ring-spins","machine":"atp-synthase","kind":"qa","prompt":"Protons flow back into the mitochondrion through ATP synthase, like water through a mill. What does that flow do to the part of the machine in the membrane?","answer":"It spins it: the membrane ring turns like a rotor.","explanation":"Each proton rides the ring almost a full turn and then leaves on the other side.","section":"mechanism","topic":"parts","sources":["machine:summary","step:The c-ring turns one step","analogy:A water turbine below a dam"],"difficulty":1,"url":"/machines/atp-synthase#mechanism","cites":[{"source":"machine:summary","machine":"atp-synthase","label":"Summary","section":"summary"},{"source":"step:The c-ring turns one step","machine":"atp-synthase","label":"Step: The c-ring turns one step","section":"mechanism"},{"source":"analogy:A water turbine below a dam","machine":"atp-synthase","label":"Analogy: A water turbine below a dam","section":"story"}]},{"id":"atp-synthase-stalk-changes-sites","machine":"atp-synthase","kind":"qa","prompt":"The spinning ring turns a stalk that reaches into the head of the machine, where ATP is made. What does the turning stalk do to the catalytic sites in the head?","answer":"It forces each site to change shape in turn: take in ADP and phosphate, make ATP, then let it go.","explanation":"The three sites are always in different states, and the pattern turns with the shaft.","section":"mechanism","topic":"cycle","sources":["step:Each β changes shape","mechanism:Each β cycles through three states","stop:site"],"difficulty":2,"url":"/machines/atp-synthase#mechanism","cites":[{"source":"step:Each β changes shape","machine":"atp-synthase","label":"Step: Each β changes shape","section":"mechanism"},{"source":"mechanism:Each β cycles through three states","machine":"atp-synthase","label":"Step: Each β cycles through three states","section":"mechanism"},{"source":"stop:site","machine":"atp-synthase","label":"Big picture: Catalytic site","section":"story"}]},{"id":"atp-synthase-atp-per-turn","machine":"atp-synthase","kind":"cloze","prompt":"The head of ATP synthase has three catalytic sites, and each makes one ATP as the stalk turns past. So one full turn of the rotor makes {{three}} ATP.","answer":"three","section":"summary","topic":"numbers","sources":["stat:ATP per full turn","fact:A13"],"difficulty":1,"url":"/machines/atp-synthase#summary","cites":[{"source":"stat:ATP per full turn","machine":"atp-synthase","label":"Key number: ATP per full turn","section":"summary"},{"source":"fact:A13","machine":"atp-synthase","label":"ATP made per turn: 3 ATP per turn","section":"story"}]},{"id":"atp-synthase-turn-rate","machine":"atp-synthase","kind":"qa","prompt":"In a working mitochondrion, the rotor of ATP synthase spins very fast. Roughly how many turns does it make each second?","answer":"About 100 turns per second.","explanation":"At three ATP per turn, that is about 300 ATP per second from one machine. The rate is an estimate, not a direct measurement.","section":"story","topic":"numbers","sources":["fact:A14","stat:Turn rate in mitochondria","fact:A22"],"difficulty":1,"url":"/machines/atp-synthase#story","cites":[{"source":"fact:A14","machine":"atp-synthase","label":"Turn rate in mitochondria: 100 turns per second","section":"story"},{"source":"stat:Turn rate in mitochondria","machine":"atp-synthase","label":"Key number: Turn rate in mitochondria","section":"summary"},{"source":"fact:A22","machine":"atp-synthase","label":"ATP per second, one synthase: 300 per second","section":"story"}]},{"id":"atp-synthase-body-weight-per-day","machine":"atp-synthase","kind":"qa","prompt":"Your body remakes ATP all day, almost all of it in ATP synthase. Roughly how much ATP does a person remake each day?","answer":"About their own body weight.","explanation":"Each ATP is spent and recharged within about a minute, so the cell must remake it again and again.","section":"story","topic":"purpose","sources":["fact:A2","stop:body","story:summary","fact:A21"],"difficulty":1,"url":"/machines/atp-synthase#story","cites":[{"source":"fact:A2","machine":"atp-synthase","label":"ATP remade per day: 1 body weight","section":"story"},{"source":"stop:body","machine":"atp-synthase","label":"Big picture: You","section":"story"},{"source":"story:summary","machine":"atp-synthase","label":"Big picture","section":"story"},{"source":"fact:A21","machine":"atp-synthase","label":"Time one ATP lasts before it is spent: 40 s","section":"story"}]},{"id":"atp-synthase-reverse-mode","machine":"atp-synthase","kind":"qa","prompt":"ATP synthase can work like a turbine or like a pump. With plenty of ATP but a weak proton gradient, which way does it run, and what does it do?","answer":"It runs backward: it spends ATP to pump protons across the membrane.","explanation":"In mitochondria, a small inhibitor protein blocks this reverse mode.","section":"mechanism","topic":"cycle","sources":["mechanism:The motor runs both ways","machine:energy"],"difficulty":2,"url":"/machines/atp-synthase#mechanism","cites":[{"source":"mechanism:The motor runs both ways","machine":"atp-synthase","label":"Step: The motor runs both ways","section":"mechanism"},{"source":"machine:energy","machine":"atp-synthase","label":"Summary","section":"summary"}]},{"id":"atp-synthase-hand-cranked-synthesis","machine":"atp-synthase","kind":"qa","prompt":"Researchers took the head of ATP synthase without its membrane part and turned its stalk with magnets. No protons were present. What did this show about how the machine makes ATP?","answer":"Turning the shaft alone is enough to make ATP; protons only supply the turning.","section":"evidence","topic":"debate","sources":["evidence:f1-mechanical-synthesis","step:ATP forms and leaves"],"difficulty":2,"url":"/machines/atp-synthase#evidence","cites":[{"source":"evidence:f1-mechanical-synthesis","machine":"atp-synthase","label":"ATP made by forcing γ to turn (Itoh H 2004)","section":"evidence","anchor":"ev-f1-mechanical-synthesis"},{"source":"step:ATP forms and leaves","machine":"atp-synthase","label":"Step: ATP forms and leaves","section":"mechanism"}]},{"id":"atp-synthase-bedaquiline","machine":"atp-synthase","kind":"qa","prompt":"Tuberculosis bacteria need their own ATP synthase to live. How does the tuberculosis drug bedaquiline stop it?","answer":"It jams the rotor ring, so the motor stalls.","explanation":"It treats multidrug-resistant tuberculosis. Structures of the drug on the human enzyme guide safer versions.","section":"summary","topic":"purpose","sources":["frontier:Drugs that jam the rotor","species:Mycobacteria"],"difficulty":1,"url":"/machines/atp-synthase#summary","cites":[{"source":"frontier:Drugs that jam the rotor","machine":"atp-synthase","label":"Open question: Drugs that jam the rotor","section":"summary"},{"source":"species:Mycobacteria","machine":"atp-synthase","label":"Mycobacteria","section":"summary"}]},{"id":"atp-synthase-flagellar-link","machine":"atp-synthase","kind":"qa","prompt":"The bacterial flagellar motor runs on the same kind of proton gradient as ATP synthase. What does it make from that proton flow instead of ATP?","answer":"Rotation: it turns the flow straight into turning, with no ATP in between.","explanation":"Part of the flagellum's export machine also looks like the ATP synthase head, a hint of a shared ancestor.","section":"story","topic":"purpose","sources":["link:flagellar-motor","evolution:Shared parts with the flagellum"],"difficulty":1,"url":"/machines/atp-synthase#story","cites":[{"source":"link:flagellar-motor","machine":"atp-synthase","label":"Link to Bacterial flagellar motor","section":"story"},{"source":"evolution:Shared parts with the flagellum","machine":"atp-synthase","label":"Shared parts with the flagellum","section":"summary"}]}]}