The protein-structure pathway
A good order to try, not a rulebook. These nineteen rungs build on one another: each assumes the one before it, so you can start at the right place for your age and climb. Every rung is a free, no-install tool — some here on Fold Commons, some on our sibling site Spark & Anvil. Nothing is collected.
This is a suggested pathway, informed by curriculum standards and the misconceptions teachers see most — it is not a claim about how much anyone learns. Skip around freely; the arrows just show what tends to make the next rung easier.
Ages 9-14
Start with a cell and its parts, and climb to how a protein's shape does its job and how a prediction can be sure in some places and unsure in others.
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BioForge Spark & Anvil
Cells have parts, and proteins do most of the work.
Start here Spark & AnvilYou have to know a protein is a working part of a cell before its shape can mean anything.
anchored to NGSS LS1.A
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Junior explorer Fold Commons
A protein is a 3D shape, not a line of letters.
liveafter rung 1: Once a protein is a working part, the first real leap is seeing it as a shape you can turn, not a string.
anchored to a protein is a shape, not a line
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ProteinQuest Fold Commons
The shape is built from twenty amino acids that differ in character - some shun water, some love it.
liveafter rung 2: A shape has to be made of something: the twenty amino acids, sorted by whether they hide from water, are the pieces that build it.
anchored to 20 amino acids differ in character
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TraitForge Spark & Anvil
DNA -> mRNA -> codon -> amino acid; one changed letter can change one amino acid.
Spark & Anvilafter rung 3: If amino acids are the pieces, the next question is where they come from - the gene spells them out, one codon at a time.
anchored to MS-LS3-1 (one letter -> one amino acid)
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NotMarbles Fold Commons - with VerbSnap & FlexiFit
The shape does the job, and shapes move and change when they bind - they are not rigid and not a line.
liveafter rung 4: Knowing the pieces and where they come from, you can ask what the folded shape actually does - and see that it flexes rather than sitting still.
anchored to shape does the job; shapes move
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VanishPoint Fold Commons - with PencilOrInk & HearTheChain
A predicted model is sure of its shape in some places and unsure in others - four honest colours.
liveafter rung 5: Now that shapes matter, you can look at a real prediction and read where the model is confident and where it is only guessing.
anchored to M03 (confidence, qualitative)
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DisorderDuty Fold Commons - with TwoIslands
"Fuzzy" can mean disordered-and-working, not wrong.
liveafter rung 6: Once you can read low confidence, the trap is reading it as failure - so next you learn a fuzzy region is often flexible on purpose.
anchored to M05 (disorder is not error)
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MicrobeLab Spark & Anvil
Proteins recognise each other - antibodies, receptors - the bridge to interfaces.
Spark & Anvilafter rung 7: A single flexible shape leads naturally to shapes meeting shapes: how proteins recognise and grip one another.
anchored to M02 (recognition)
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HingeHunt Fold Commons - with BuriedBet
Residues bury at interfaces, and two domains may or may not "know" where each other sit (a first look at PAE).
liveafter rung 8: Once proteins meet, you can ask whether the model knows how their parts are arranged relative to each other - the last 9-14 step.
anchored to M04 (inter-domain placement, PAE)
Ages 15-18
Re-enter with the chemistry of bonds and the hydrophobic effect, then read real confidence numbers, quaternary structure, variants, isoforms, medicine and the blind tests that made prediction trustworthy.
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ChemQuest Spark & Anvil - then ReactQuest
Bonds, polarity, and the hydrophobic effect - the chemistry the older track re-enters on.
Start here Spark & AnvilThe 15-18 ladder restarts from the chemistry that makes folding happen at all: why oily parts hide from water.
anchored to IB B1.2.9 (bonds, polarity, hydrophobic effect)
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HelixQuest Spark & Anvil
Gene sequence and variation -> protein -> evolution.
Spark & Anvilafter rung 10: With the chemistry in place, you connect the gene sequence to the protein it encodes and how changes in it drive evolution.
anchored to HS-LS1-1 (gene -> protein -> evolution)
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ShapeForge Spark & Anvil - hands off to the viewer
Predict local structure; hydrophobics bury; sickle cell is one changed letter. This rung hands off into the Fold Commons viewer.
Spark & Anvilafter rung 11: Predicting local structure from sequence is exactly where a real AlphaFold model becomes worth reading - the hand-off point.
anchored to AP SYI-1.B.2 (predict local structure)
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NumberReader Fold Commons - the scored real-numbers read
Read the real per-residue pLDDT numbers off a structure and say plainly: this is a prediction, not an experiment.
newafter rung 12: Having predicted structure, you open a real model and read its actual confidence numbers - the 15-18 numeric companion to the 9-14 colour read.
anchored to PDB-101 (read the model, part 1)
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GripChain Fold Commons
Several chains assemble, and binding at one site changes another - quaternary structure and allostery.
liveafter rung 13: Reading one chain's numbers leads to several chains together, and how gripping in one place is felt in another.
anchored to M13 (quaternary structure, allostery)
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DomainCuts Fold Commons - with FoldCompare & WhatsMissing
Domains and quantitative PAE; RMSD against the real PDB structure; a model omits cofactors and partners.
liveafter rung 14: With assemblies in mind, you carve domains, read PAE as numbers, check the model against experiment, and notice what it leaves out.
anchored to PDB-101 (read the model, parts 2-3)
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TolerancePaint Fold Commons - with OneLetterLottery
Most variants are tolerated; AlphaMissense is a research tool, not a diagnosis.
liveafter rung 15: Knowing what a model shows and omits, you can ask what one changed letter does - and that most changes are harmless.
anchored to M08 (variants; AlphaMissense research-only)
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SpliceSplit Fold Commons
One gene can make several proteins - isoforms - each folding to its own shape.
liveafter rung 16: After single-letter changes, the next surprise is that one gene can be spliced into several different folded proteins.
anchored to M10 (isoforms)
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PocketScout Fold Commons - with AntibodyAtlas, PhenoFold & ClinicalAtlas
Structure -> pocket -> medicine; phenotype -> gene -> structure.
liveafter rung 17: Once you can read shapes, variants and isoforms, you can hunt the pockets a medicine grips - where the science becomes useful.
anchored to M02 (structure -> pocket -> medicine)
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CASP, explained Fold Commons - with Nobel structures
Why "prediction" became trustworthy - decades of CASP blind tests, and a Nobel Prize.
liveafter rung 18: The ladder ends by asking why we trust predictions at all: the blind tests that proved they work.
anchored to M07 (why prediction is trusted)
How to read this ladder
Each rung assumes the rung before it — that is the arrow. Read them as prerequisites, not grades: rung 6 (reading a model's confidence) is easier once rung 5 (a shape does a job) makes sense, which is easier once rung 3 (the twenty amino acids) does. The two age bands each have their own “Start here” rung: ages 9–14 begin at a cell and its parts; ages 15–18 re-enter at the chemistry of bonds and the hydrophobic effect. The same idea can sit at two rungs at different depths — reading confidence as four honest colours (rung 6, 9–14) and reading the real confidence numbers (rung 13, 15–18) are different rungs, on purpose.
The upstream biology and chemistry rungs live on our sibling site Spark & Anvil, which builds the same free, non-profit way. Fold Commons owns everything from “here is a real protein” onward. Everything AlphaFold shows is a prediction, not an experiment.