{"format":"molecular-machines.cards","version":1,"updated":"2026-10-12","decks":[{"machine":"ribosome","name":"Ribosome","count":10,"url":"/learn/cards/ribosome.json"}],"cards":[{"id":"ribosome-purpose","machine":"ribosome","kind":"qa","prompt":"Every protein in your body, and every machine in this atlas, comes off one kind of machine. What does the ribosome do?","answer":"It reads a messenger RNA and builds the matching protein chain.","explanation":"RNA polymerase writes the messenger RNA. The ribosome reads it.","section":"summary","topic":"purpose","sources":["machine:tagline","story:summary","link:rna-polymerase"],"difficulty":1,"url":"/machines/ribosome#summary","cites":[{"source":"machine:tagline","machine":"ribosome","label":"Summary","section":"summary"},{"source":"story:summary","machine":"ribosome","label":"Big picture","section":"story"},{"source":"link:rna-polymerase","machine":"ribosome","label":"Link to RNA polymerase II","section":"story"}]},{"id":"ribosome-three-letters","machine":"ribosome","kind":"cloze","prompt":"The ribosome reads a messenger RNA like a tape. It adds one amino acid for every {{three}} letters it reads.","answer":"three","explanation":"Each three-letter word is a codon. A matching tRNA brings the amino acid for it.","section":"summary","topic":"cycle","sources":["story:summary","stop:machine"],"difficulty":1,"url":"/machines/ribosome#summary","cites":[{"source":"story:summary","machine":"ribosome","label":"Big picture","section":"story"},{"source":"stop:machine","machine":"ribosome","label":"Big picture: Ribosome at work","section":"story"}]},{"id":"ribosome-check","machine":"ribosome","kind":"qa","prompt":"A tRNA arrives at the ribosome with an amino acid, and the ribosome tests it against the codon. What happens to a tRNA that does not match?","answer":"It falls off again and is rejected.","explanation":"Wrong tRNAs bind fast and fall off fast, so the ribosome can try many at little cost.","section":"mechanism","topic":"cycle","sources":["step:EF-Tu brings an aminoacyl-tRNA","mechanism:Decoding"],"difficulty":2,"url":"/machines/ribosome#mechanism","cites":[{"source":"step:EF-Tu brings an aminoacyl-tRNA","machine":"ribosome","label":"Step: EF-Tu brings an aminoacyl-tRNA","section":"mechanism"},{"source":"mechanism:Decoding","machine":"ribosome","label":"Step: Decoding","section":"mechanism"}]},{"id":"ribosome-rna-joins","machine":"ribosome","kind":"qa","prompt":"The ribosome is built from RNA and protein. At its core two amino acids are joined into a chain. Which of the two materials does that chemistry?","answer":"RNA: no protein sits near the new bond.","explanation":"So the ribosome is an RNA machine at its heart. Its proteins sit on the surface.","section":"evidence","topic":"parts","sources":["evidence:nissen2000-rna-catalyst","mechanism:Peptide bond formation","fact:s-no-protein"],"difficulty":1,"url":"/machines/ribosome#evidence","cites":[{"source":"evidence:nissen2000-rna-catalyst","machine":"ribosome","label":"Distance from the forming peptide bond to the nearest protein (Nissen P 2000)","section":"evidence","anchor":"ev-nissen2000-rna-catalyst"},{"source":"mechanism:Peptide bond formation","machine":"ribosome","label":"Step: Peptide bond formation","section":"mechanism"},{"source":"fact:s-no-protein","machine":"ribosome","label":"Radius around the new peptide bond with no protein: 1.8 nm","section":"story"}]},{"id":"ribosome-ratchet","machine":"ribosome","kind":"qa","prompt":"After each bond forms, the ribosome must move on to the next codon. How do its two subunits move to make that step?","answer":"They rotate against each other, and the mRNA moves on by one codon.","explanation":"The first part of the turn happens by thermal motion. A helper protein with GTP then completes the step.","section":"mechanism","topic":"cycle","sources":["machine:summary","mechanism:Ratchet and translocation","step:The subunits ratchet"],"difficulty":2,"url":"/machines/ribosome#mechanism","cites":[{"source":"machine:summary","machine":"ribosome","label":"Summary","section":"summary"},{"source":"mechanism:Ratchet and translocation","machine":"ribosome","label":"Step: Ratchet and translocation","section":"mechanism"},{"source":"step:The subunits ratchet","machine":"ribosome","label":"Step: The subunits ratchet","section":"mechanism"}]},{"id":"ribosome-fuel","machine":"ribosome","kind":"qa","prompt":"The ribosome uses helper proteins to bring each tRNA and to move along the mRNA. What fuel do these helpers burn?","answer":"GTP.","explanation":"The cell recharges GTP with a phosphate taken from ATP.","section":"summary","topic":"purpose","sources":["machine:energy","link:atp-synthase"],"difficulty":1,"url":"/machines/ribosome#summary","cites":[{"source":"machine:energy","machine":"ribosome","label":"Summary","section":"summary"},{"source":"link:atp-synthase","machine":"ribosome","label":"Link to ATP synthase","section":"story"}]},{"id":"ribosome-mammal-rate","machine":"ribosome","kind":"qa","prompt":"A ribosome adds amino acids to the chain one at a time. In mammal cells, roughly how many does it add each second?","answer":"About five or six.","explanation":"At that speed a typical protein of 400 amino acids takes a little over a minute.","section":"story","topic":"numbers","sources":["fact:R9","stop:machine"],"difficulty":1,"url":"/machines/ribosome#story","cites":[{"source":"fact:R9","machine":"ribosome","label":"Speed of a ribosome in mammal cells: 5.6 amino acids per second","section":"story"},{"source":"stop:machine","machine":"ribosome","label":"Big picture: Ribosome at work","section":"story"}]},{"id":"ribosome-body-protein","machine":"ribosome","kind":"qa","prompt":"Your body builds protein all day, to grow, to repair and to replace what wears out. Roughly how much protein does it build each day?","answer":"A few hundred grams.","explanation":"Every gram of it comes off ribosomes.","section":"story","topic":"numbers","sources":["fact:R2","stop:body","fact:R1"],"difficulty":2,"url":"/machines/ribosome#story","cites":[{"source":"fact:R2","machine":"ribosome","label":"Protein turnover in the whole body: 300–400 g per day","section":"story"},{"source":"stop:body","machine":"ribosome","label":"Big picture: You, building","section":"story"},{"source":"fact:R1","machine":"ribosome","label":"Protein made by the whole body per day, small study: 175 g per day","section":"story"}]},{"id":"ribosome-antibiotics","machine":"ribosome","kind":"qa","prompt":"Many antibiotics kill bacteria by jamming their ribosomes. How do these drugs stop the machine?","answer":"Each drug binds one site on the ribosome's RNA, for example in the exit tunnel or the catalytic centre.","explanation":"Structures show where each drug class sits, which helps people design new drugs.","section":"mechanism","topic":"parts","sources":["frontier:Drug design at the tunnel and catalytic centre"],"difficulty":2,"url":"/machines/ribosome#mechanism","cites":[{"source":"frontier:Drug design at the tunnel and catalytic centre","machine":"ribosome","label":"Open question: Drug design at the tunnel and catalytic centre","section":"summary"}]},{"id":"ribosome-rna-first","machine":"ribosome","kind":"qa","prompt":"The catalytic centre of the ribosome holds no protein. The proteins only sit on the surface and hold the RNA folds stable. What does that hint about how the ribosome first evolved?","answer":"RNA came first, and protein was added around it.","explanation":"This fits an RNA-first origin.","section":"summary","topic":"debate","sources":["evolution:RNA came first","fact:s-no-protein"],"difficulty":2,"url":"/machines/ribosome#summary","cites":[{"source":"evolution:RNA came first","machine":"ribosome","label":"RNA came first","section":"summary"},{"source":"fact:s-no-protein","machine":"ribosome","label":"Radius around the new peptide bond with no protein: 1.8 nm","section":"story"}]}]}