{"format":"molecular-machines.cards","version":1,"updated":"2026-10-12","decks":[{"machine":"dynein","name":"Dynein","count":10,"url":"/learn/cards/dynein.json"}],"cards":[{"id":"dynein-direction","machine":"dynein","kind":"qa","prompt":"Kinesin carries cargo outward along microtubules. Cytoplasmic dynein runs on the same tracks. Which way does dynein carry its cargo?","answer":"Toward the minus end, back toward the centre of the cell.","explanation":"So kinesin and dynein pull cargo in opposite directions, and nerve vesicles carry both.","section":"summary","topic":"purpose","sources":["machine:summary","machine:tagline","link:kinesin"],"tags":["direction","transport"],"difficulty":1,"url":"/machines/dynein#summary","cites":[{"source":"machine:summary","machine":"dynein","label":"Summary","section":"summary"},{"source":"machine:tagline","machine":"dynein","label":"Summary","section":"summary"},{"source":"link:kinesin","machine":"dynein","label":"Link to Kinesin","section":"story"}]},{"id":"dynein-mucus-escalator","machine":"dynein","kind":"qa","prompt":"Every breath brings in dust and germs. Dynein motors drive the tiny hairs, called cilia, that line your airways. What do these cilia move?","answer":"A sheet of mucus, up toward your throat.","explanation":"The mucus traps dust and germs and moves a few millimetres a minute.","section":"story","topic":"purpose","sources":["stop:escalator","fact:D2","story:question"],"tags":["cilia","lungs"],"difficulty":1,"url":"/machines/dynein#story","cites":[{"source":"stop:escalator","machine":"dynein","label":"Big picture: The mucus escalator","section":"story"},{"source":"fact:D2","machine":"dynein","label":"Speed of the mucus layer: 5.5 mm per minute","section":"story"},{"source":"story:question","machine":"dynein","label":"Big picture","section":"story"}]},{"id":"dynein-lung-cilia-count","machine":"dynein","kind":"qa","prompt":"The cilia in your airways each beat 10 to 20 times a second, all day. Roughly how many motile cilia line an adult lung?","answer":"About three trillion.","section":"story","topic":"numbers","sources":["fact:D1","story:summary"],"tags":["cilia","scale"],"difficulty":1,"url":"/machines/dynein#story","cites":[{"source":"fact:D1","machine":"dynein","label":"Motile cilia in an adult lung: 3 × 10^12","section":"story"},{"source":"story:summary","machine":"dynein","label":"Big picture","section":"story"}]},{"id":"dynein-sliding-to-bending","machine":"dynein","kind":"qa","prompt":"Inside a cilium, dynein arms pull one rail past the next. The rails are tied together, so they cannot slide far. What does the cilium do instead?","answer":"It bends.","explanation":"Like a bimetal strip, two tied layers turn a change in length into a bend. In a cilium, motors make that change.","section":"story","topic":"cycle","sources":["stop:sliding","analogy:A bimetal strip","stop:axoneme"],"tags":["cilia","bending"],"difficulty":1,"url":"/machines/dynein#story","cites":[{"source":"stop:sliding","machine":"dynein","label":"Big picture: Sliding becomes bending","section":"story"},{"source":"analogy:A bimetal strip","machine":"dynein","label":"Analogy: A bimetal strip","section":"story"},{"source":"stop:axoneme","machine":"dynein","label":"Big picture: The axoneme","section":"story"}]},{"id":"dynein-pcd","machine":"dynein","kind":"qa","prompt":"In a rare disease, the airway cilia are missing their dynein arms. What goes wrong in the lungs?","answer":"The cilia cannot beat, so the mucus does not clear.","explanation":"This is primary ciliary dyskinesia. In about half of the people affected, the organs also develop on the wrong side.","section":"story","topic":"purpose","sources":["fact:D13","fact:D14","story:summary"],"tags":["disease","cilia"],"difficulty":1,"url":"/machines/dynein#story","cites":[{"source":"fact:D13","machine":"dynein","label":"Cilia in primary ciliary dyskinesia: Immotile no dynein arms","section":"story"},{"source":"fact:D14","machine":"dynein","label":"Births with primary ciliary dyskinesia: 1 in 15,000 live births","section":"story"},{"source":"story:summary","machine":"dynein","label":"Big picture","section":"story"}]},{"id":"dynein-atp-closes-ring","machine":"dynein","kind":"qa","prompt":"Each dynein motor head is a ring of six ATP-binding units, with a long stalk that ends in a small foot on the track. What happens to the ring when ATP binds?","answer":"It closes.","explanation":"The closing slides the stalk helices, and the foot at the tip lets go of the microtubule.","section":"mechanism","topic":"cycle","sources":["mechanism:ATP closes the ring","step:ATP binds the rear head","step:The stalk slides and the foot lets go"],"tags":["ring","atp"],"difficulty":1,"url":"/machines/dynein#mechanism","cites":[{"source":"mechanism:ATP closes the ring","machine":"dynein","label":"Step: ATP closes the ring","section":"mechanism"},{"source":"step:ATP binds the rear head","machine":"dynein","label":"Step: ATP binds the rear head","section":"mechanism"},{"source":"step:The stalk slides and the foot lets go","machine":"dynein","label":"Step: The stalk slides and the foot lets go","section":"mechanism"}]},{"id":"dynein-linker-springs-back","machine":"dynein","kind":"qa","prompt":"The closed ring forces dynein's lever-like linker into a bent shape. The head then lands on the track again and its phosphate leaves. What does the linker do, and what moves?","answer":"It straightens, and the tail and cargo move forward: the power stroke.","explanation":"The foot holds the track while the bent linker springs back.","section":"mechanism","topic":"cycle","sources":["step:Phosphate leaves and the linker straightens","mechanism:Rebinding triggers the power stroke","mechanism:The ring primes the linker"],"tags":["linker","power-stroke"],"difficulty":2,"url":"/machines/dynein#mechanism","cites":[{"source":"step:Phosphate leaves and the linker straightens","machine":"dynein","label":"Step: Phosphate leaves and the linker straightens","section":"mechanism"},{"source":"mechanism:Rebinding triggers the power stroke","machine":"dynein","label":"Step: Rebinding triggers the power stroke","section":"mechanism"},{"source":"mechanism:The ring primes the linker","machine":"dynein","label":"Step: The ring primes the linker","section":"mechanism"}]},{"id":"dynein-activators","machine":"dynein","kind":"qa","prompt":"On its own, human cytoplasmic dynein is mostly switched off. What does it need before it carries cargo?","answer":"Partner proteins: dynactin and a cargo adaptor, which also link it to the cargo.","section":"summary","topic":"parts","sources":["machine:summary","component:dynactin","component:cargo adaptor"],"tags":["activation","partners"],"difficulty":2,"url":"/machines/dynein#summary","cites":[{"source":"machine:summary","machine":"dynein","label":"Summary","section":"summary"},{"source":"component:dynactin","machine":"dynein","label":"Part: dynactin","section":"summary"},{"source":"component:cargo adaptor","machine":"dynein","label":"Part: cargo adaptor","section":"summary"}]},{"id":"dynein-tug-of-war","machine":"dynein","kind":"qa","prompt":"Kinesin and dynein pull the same cargo in opposite directions. In a test tube, one dynein complex was tied to one kinesin. What happened?","answer":"They held each other back, and the pair crawled slowly.","explanation":"The dynein complex resisted the kinesin. Mixed teams like this could give controlled two-way transport.","section":"evidence","topic":"debate","sources":["evidence:belyy2016-tug-of-war","frontier:Balanced bidirectional transport","link:kinesin"],"tags":["kinesin","tug-of-war"],"difficulty":2,"url":"/machines/dynein#evidence","cites":[{"source":"evidence:belyy2016-tug-of-war","machine":"dynein","label":"One dynein-dynactin-BICD2N complex against one kinesin-1 (Belyy V 2016)","section":"evidence","anchor":"ev-belyy2016-tug-of-war"},{"source":"frontier:Balanced bidirectional transport","machine":"dynein","label":"Open question: Balanced bidirectional transport","section":"summary"},{"source":"link:kinesin","machine":"dynein","label":"Link to Kinesin","section":"story"}]},{"id":"dynein-cell-division","machine":"dynein","kind":"qa","prompt":"Cytoplasmic dynein is not only a cargo carrier. When a cell divides, what does dynein help to do?","answer":"Build and place the spindle and move the chromosomes.","explanation":"It also helps separate the centrosomes and silence the checkpoint.","section":"story","topic":"purpose","sources":["fact:D12"],"tags":["cell-division","spindle"],"difficulty":2,"url":"/machines/dynein#story","cites":[{"source":"fact:D12","machine":"dynein","label":"Jobs of dynein in cell division: Several jobs","section":"story"}]}]}