Most Things Biology

2.6 The FMF Molecule Cast

Case home  ·  Start at the beginning  ·  The Reveal

Time To Read

24–37 minutes

Date Last Modified

Just Enough Chemistry · Chapter 6 of 7

1985–87, ages ten to twelve: a move for Dad’s job, no Dr. Gonzalez in the new town, and “My fever calendar is in a box somewhere.” Then, at twelve, a different hospital and the same idea — a stomach so bad she couldn’t stand, a fever of 102, “blood and X-ray and nothing,” and a second psychiatrist who wrote “adjustment” on her pad. This chapter brings the cast onstage: an ion, a sugar, a lipid signal, a plant alkaloid, a messenger made long and cut short, a sensor with five rooms, and the proteins the liver pours out on command — sorted by class, weighed, and checked against what a 1987 laboratory could actually see.

The question you will answer

Name a molecule’s class and you can predict where it travels, what it can cross, what makes it and how a drug might reach it. At twelve, the blood was drawn and the answer came back “nothing.” The question for the chapter: which members of the cast behind an attack could that blood draw have measured — and what would a marker that stays high, in good weeks as well as bad, be telling you?

Opener · Nobody in the Room Could See Them · about 2¼ minutes

The opener is the same narrated animation you will watch in Scene 1.

Watch it in Scene 1 ↓

Watch the opener first. It sets the question; the chapter answers it.

1

Read the chart

Patient chart · Stina

1985–1987 · ages 10–12 — the move, the second psychiatrist, and the markers across these years

1985–86 · 10–11
The family moves for Dad’s job. No Dr. Gonzalez in the new town; the three-month visit never happens — “first Mom was too tired, then we were packing.” “My fever calendar is in a box somewhere.” Mom’s headaches are back.

1987 · 12
ER at a different hospital: a stomach so bad she can’t stand, a fever of 102, “blood and X-ray and nothing,” then a referral to a second psychiatrist. She tells her everything, flat and in order — that she is “sick of being told there’s nothing wrong with me,” that nobody is in her corner. The psychiatrist writes “adjustment” on her pad and offers to talk more about Mom. “I said no thank you.”

Across these years
Inflammatory markers (CRP, ESR, serum amyloid A) high even in her good weeks; albumin a little low, globulins a little high; red-cell count and hematocrit high, erythropoietin elevated (the Blood module’s question). The record gives no dates and no values for these years.

Told
“Adjustment reaction to parental illness.” “Consider school avoidance.” “Likely lab error.” “Probably stress.” “You’re just a little dehydrated.”

Chart clues this module: 2 · this module (named here; logged in Chapter 7)

Before you go on · your prediction

At twelve: a fever of 102, “blood and X-ray and nothing,” and a chart that read “Adjustment reaction to parental illness.” Before you meet the molecules behind an attack, what is the best reading of “nothing” on that blood draw?

Open the one you lean toward. Nothing is recorded and nothing is revealed — you come back to it at the end.

That there was nothing to find — “Adjustment reaction to parental illness”

Watch Scene 1’s ruler: for each molecule, ask whether its level changes during an attack, and whether a 1987 hospital lab could measure it at all.

That the blood was right but misread — “Likely lab error”

Watch Scene 4: what a true lab error looks like on a repeat draw, and what an acute-phase signal looks like across good weeks and bad.

That the tests ordered could not see most of the molecules doing the work

Watch Scenes 1 and 4: which cast members were routine in 1987, which existed only in research labs, and which nobody had discovered yet.

From Stina’s diary

Age 12 · “In my corner”

2

The story

Three short movements: the case, the anatomy and physiology, then the tie back to Stina. Each links to the scene where you’ll see it move.

I · Blood and X-ray and nothing

The move came when she was ten or eleven — Dad’s job. Nobody in the new town knew about the fevers, which Mom said was a fresh start. Stina thought it meant nobody there was going to believe her either, “and they haven’t even had the chance to not believe me yet.” There was no Dr. Gonzalez. They never went back for the three-month visit the doctor had asked for. “My fever calendar is in a box somewhere.” Mom’s headaches were back. At twelve, in 1987, the emergency room sent her to a psychiatrist again. Different hospital, same idea: a stomach so bad she couldn’t stand, a fever of 102, “blood and X-ray and nothing,” and then a referral. This one was a woman with a gray braid, and there was a box of tissues on the little table beside the chair. Stina decided she wasn’t going to waste it. She told her everything — that Mom’s brain tumors had crushed her (“Not her head. Her.”), that she was “sick of being told there’s nothing wrong with me,” that after the second operation there was nobody in her corner anymore. She said it flat, in order, and she didn’t use the tissues. The psychiatrist listened, and that was worth something. Then she wrote “adjustment” something on her pad and asked whether Stina would like to come back and talk more about Mom. Stina had talked about her stomach for ten minutes and about Mom for two, and the doctor picked Mom. “I said no thank you.”

See it move: Scene 1 · Nobody in the Room Could See Them · Scene 4 · The Liver Answers

II · Name the class

Think of this chapter as a curtain call: every character in the disease walks back onstage riding its biomolecule class, and classification isn’t busywork — it’s a superpower. Name the class and you’ve half-explained the job. Sodium is an ion, 23 daltons, counted on every ER panel since long before 1987. Glucose is a sugar. Prostaglandin E₂ is lipid-derived, made from arachidonic acid by COX-2 at the brain’s doorstep, which is why aspirin-type drugs can lower a fever (Chapter 4). Colchicine is a plant alkaloid — a small, nitrogen-containing ring compound, about 400 daltons — small and fat-soluble enough to slip through a membrane into a white cell. The rest are proteins, and each is its fold: interleukin-1β, a cytokine (a small signaling protein) that is built long and inactive and cut to 17,000 daltons before it can work; pyrin, a 781-amino-acid sensor with five domains that waits inside neutrophils and monocytes; C-reactive protein, five identical pieces in a ring; serum amyloid A, about 104 amino acids, which rides on HDL. CRP is a globular blood protein, dissolved and drifting; SAA rides on HDL; both are eminently measurable today, and the liver makes both on orders from interleukin-6. The ESR, which you will see on old charts beside them, is not a molecule at all: it is a test of how fast red cells settle in a tube, and it speeds up when fibrinogen and globulins rise. The class isn’t trivia; it’s the reason the medicine works. A protein messenger has to act from outside, on a receptor; a small alkaloid can reach the machinery inside.

See it move: Scene 1 · Nobody in the Room Could See Them · Scene 2 · Pyrin, Five Rooms · Scene 3 · The Messenger Made Long · Scene 5 · An Alkaloid, Not a Protein

III · The cast nobody in the room could see

Here is what the narrator knows about that room in 1987. Sodium, potassium, glucose, a white-cell count and a total protein with its albumin were ordinary hospital tests; an ESR was too. C-reactive protein had been discovered in 1930 and could be measured, but it was not the reflex test for a child’s belly pain. Serum amyloid A was a research measurement. Interleukin-1β’s gene had been cloned in 1984 — the year of her first psychiatrist — and the molecule could be found only in research laboratories. Pyrin was unknown; its gene, MEFV, would not be found until 1997. And colchicine, the plant alkaloid that stops FMF attacks, had been the standard treatment for this disease since the early 1970s, before she was born or near enough; by 1986 a study had shown it also prevents the amyloid that years of untreated attacks can lay down. The treatment existed. The diagnosis didn’t. Honesty flag: the diary records only “blood”; nothing says which tests that blood went to at twelve, and the chart gives no values for any of these years. Its one lab row is undated — “Across these years” — and lists inflammatory markers high even in her good weeks, a protein ratio flipped, and the replies: “Likely lab error.” “Probably stress.” Because serum amyloid A was not a routine test in 1987, that row cannot describe a childhood ER draw; it describes a pattern the record carries across years it does not date. A marker that rises with each attack and falls between them describes something that starts and stops. A marker that never comes down describes something that never stops. Chapter 7 logs the clue.

See it move: Scene 1 · Nobody in the Room Could See Them · Scene 4 · The Liver Answers

3

Watch · explore · think · check

5 scenes. Each one has a short animation or a slide, something to explore, a true/false spot-check of your thinking, and a quick check. Every scene gives you an evidence card for your board.

How to read the scenes

  • Animation (dark teal) — a short animated explainer, one idea each
  • Slide (dark teal) — a still to study: a micrograph, a diagram or a map
  • Explore (purple) — something to push on while you watch
  • Game (purple) — a quick challenge
  • Think (gold) — reason it out, then spot-check yourself with a few true/false questions; not graded
  • Check (gold) — a quick H5P that scores itself

Scene 1 of 5

Nobody in the Room Could See Them

An ion, a sugar, an alkaloid, a cytokine, a sensor — and which ones a 1987 lab could weigh.

Animation · in production · 2 min 10 s

Nobody in the Room Could See Them

An ER cubicle in 1987, drawn in muted line: a girl curled on a gurney, a thermometer at 102, a tube of blood leaving on a tray. The tube lands in a rack and the camera dives into the plasma, where the cast takes a curtain call along a ruler that grows by powers of ten. Na⁺ (23 daltons, ION). Glucose (180, SUGAR). Prostaglandin E₂ (about 350, LIPID-DERIVED). Colchicine (about 400, PLANT ALKALOID) beside a purple autumn crocus. Serum amyloid A (about 12,000, PROTEIN) climbing onto an HDL particle. IL-1β (17,000, CYTOKINE), with a ghost of its longer pro-form behind it. Albumin (66,500). Pyrin (781 amino acids, about 86,000, SENSOR) glowing inside a neutrophil. C-reactive protein (five pieces in a ring, about 115,000). Then a 1987 hospital test menu — not her results; canon keeps none — slides over the ruler and a stamp marks each card: ROUTINE (Na⁺, glucose, albumin) · A TEST, NOT A MOLECULE (ESR) · AVAILABLE, NOT ROUTINE FOR A CHILD’S BELLY PAIN (CRP) · RESEARCH ONLY (SAA, IL-1β) · NOT YET DISCOVERED (pyrin — its gene, 1997). Over colchicine: IN USE FOR THIS DISEASE SINCE THE EARLY 1970s. The girl’s chart closes on one word: ADJUSTMENT.

Prefer the full lecture? Proteins (original video on the site)

Explore · in production

The size ladder

A long horizontal ruler on a logarithmic scale, marked in daltons from 10 to 10,000,000, one tick per power of ten, with a hand-drawn note: each step to the right is ten times heavier. Eleven face-up cards wait in a tray: Na⁺, glucose, prostaglandin E₂, colchicine, serum amyloid A, IL-1β (mature), pro-IL-1β, albumin, pyrin, C-reactive protein (pentamer) and an HDL particle — plus a twelfth card, ESR. Before placing each card the student predicts its spot; on release the card snaps to its true position and shows its number: Na⁺ 23 · glucose 180 · PGE₂ about 352 · colchicine about 399 · SAA about 12,000 · IL-1β 17,000 (its pro-form, 31,000, lands as a ghost to the right) · albumin about 66,500 · pyrin about 86,000 (781 amino acids) · CRP about 115,000 (five 23,000-dalton pieces) · HDL a particle of lipid and protein a few hundred thousand daltons heavy and about 8–12 nanometers across. The ESR card refuses to land: “A test, not a molecule — no place on a ruler of masses.” Every placed card flips to a back with four lines: CLASS (ion, carbohydrate, lipid-derived, alkaloid, protein, lipoprotein particle), MADE BY (absorbed from food; the liver; neutrophils and monocytes; a plant), WORKS WHERE (inside the cell, in the plasma, on a receptor), and MEASURABLE IN 1987? — Na⁺, glucose, albumin and total protein: routine; CRP: available but not routinely ordered for a child’s belly pain; SAA and IL-1β: research laboratories only; pyrin: not yet known (MEFV found in 1997); PGE₂: research only; colchicine: a drug already in use for this disease for about fifteen years; HDL: measurable as HDL cholesterol, but no reason to order it in a child’s ER. A second toggle adds a column: DOES IT CHANGE IN AN ATTACK? The reveal: the cards a 1987 ER routinely read mostly hold steady or change slowly; the ones that surge in an attack sit in the research column. “Blood and X-ray and nothing” was a true report about the wrong molecules. A last count tallies the classes — most of the cast are proteins, one is a lipid signal, one an ion, one a sugar, one a plant alkaloid — under Amy’s line: name the class and you’ve half-explained the disease. Keyboard path: Tab to a card, arrow keys slide it along the ruler one power of ten at a time, Enter drops it, F flips it; a live region reads each placement (“Colchicine, about 399 daltons, between 100 and 1,000”). A <details> text version gives the full table of masses, classes and 1987 status.

Think · not graded

Sodium, glucose and albumin could all be measured in a 1987 ER; serum amyloid A, interleukin-1β and pyrin could not. Sort the cast by whether its level changes during an attack. What do you notice about which group the ER could read — and what, exactly, does “blood and X-ray and nothing” prove?

The true/false spot-check for this prompt is in production.

Check · Drag the Words

Drag the right biomolecule class into each cast member’s sentence. Two classes are left over.

This self-scoring check is in production.

Evidence card 1

Add it to your evidence board

At twelve, a second ER: a fever of 102, “blood and X-ray and nothing,” and a referral to a psychiatrist.

Scene 2 of 5

Pyrin, Five Rooms

A 781-amino-acid sensor, a phosphate brake, and where the textbook variants sit.

Animation · in production · 2 min 05 s

Pyrin, Five Rooms

A neutrophil drifts through a capillary and opens like a house: inside, a long chain labeled PYRIN · 781 AMINO ACIDS · ~86 kDa lies along a hallway of five rooms, each lit in turn with a text label — PYD (a handshake reaching for ASC) · a LINKER with a bZIP-like stretch and two phosphate hooks · B-BOX (a zinc ion at its heart) · COILED-COIL (two pyrins twisting together) · B30.2 / PRYSPRY (a compact sandwich of β-sheets). Two enzymes, PKN1 and PKN2, hang phosphate tags on the hooks and a pair of 14-3-3 proteins clamp them: BRAKE ON. A switch labeled RhoA glows; a bacterial toxin flips it off; the tags drop, the clamps let go, the PYD reaches out, and an inflammasome ring begins to build — arrow to MODULE 3. Back to the last room: three pins land in B30.2, labeled M694V · M680I · V726A — THE TEXTBOOK VARIANTS. The room stays folded; one surface patch changes color; a threshold line on a dial drops: GAIN OF FUNCTION · LOWERED THRESHOLD. A K⁺ ion leaves a different cell with an arrow to NLRP3 — NOT PYRIN. Last, a padlocked pin hovers above the chain, not placed: HER OWN VARIANT — MODULE 4.

Prefer the full lecture? Proteins (original video on the site)

Explore · in production

Pyrin’s floor plan

Pyrin drawn as a horizontal bar 781 residues long, with a residue ruler under it and five colored domains, each with a text label and a pattern so color is never the only cue: PYD (about residues 1–92, at the N-terminal end), a LINKER carrying a short bZIP-like stretch and two phosphorylation sites marked as hooks (serine 208 and serine 242), the B-BOX (a zinc-binding fold), the COILED-COIL, and the B30.2 / PRYSPRY domain at the C-terminal end (about residues 580–775). Before clicking, the student predicts which domain does which of four jobs: grab the adaptor ASC; carry the brake; let pyrin pair with itself; sit where the textbook variants cluster. Clicking a domain opens its card. PYD: the handshake — pyrin domain to ASC’s pyrin domain, the first step in building an inflammasome. LINKER: where the cell hangs its brake. B-BOX: a small zinc-held fold that helps shape the molecule. COILED-COIL: lets pyrins link into a team. B30.2: a compact β-sandwich; its exact job is still being worked out, and it helps set how easily the sensor fires. A BRAKE toggle animates the hold: PKN1 and PKN2 attach phosphates to the two hooks and two 14-3-3 proteins clamp them (brake on). A second control, SWITCH RhoA OFF, lets a bacterial toxin icon (Clostridioides difficile toxin) disable RhoA: the enzymes go idle, the phosphates come off, 14-3-3 lets go and the PYD reaches for ASC (“the full assembly — Module 3.7”). A decoy control, K⁺ LEAVES THE CELL, does nothing to pyrin and points to NLRP3 instead (“the K⁺ that leaves a neutrophil trips a different sensor — Module 3.6–3.7”). Then PINS: the student drops three labeled pins — the textbook variants every reference describes, M694V, M680I and V726A — and each lands in the B30.2 domain (exon 10). A small ribbon thumbnail of the B30.2 domain stays folded when each pin lands, with one surface patch recolored, and a threshold dial beside it drops: the protein still folds and still works; one changed surface lets it fire too easily (gain of function, a lowered threshold — not a collapsed protein). A last pin stays locked in the tray, labeled “her own variant — where it sits, and what one copy can do, is the Chart Reveal’s question (Module 4).” It cannot be dragged. Keyboard path: Tab moves domain to domain along the bar, Enter opens a card, B toggles the brake, R switches RhoA off, P places the next pin; a live region narrates each change. A <details> text version describes the domains, the brake and the three textbook pins in a list.

Think · not graded

Pyrin doesn’t look for the germ; it watches for what certain germs do to the cell — switching RhoA off. If one changed surface makes that watcher fire a little too easily, would you expect the protein to be missing, crumpled, or present and touchy? And what would that predict about attacks that come with no infection behind them?

The true/false spot-check for this prompt is in production.

Check · Single Choice

In the textbook FMF variants — the ones every reference describes, such as M694V — what has happened to pyrin?

This self-scoring check is in production.

Evidence card 2

Add it to your evidence board

At eleven, an attack “blows in like a storm and leaves like somebody switched off a light” — an alarm with a fast on and a fast off, and nothing in the diary says a germ was ever found.

Scene 3 of 5

The Messenger Made Long

Built as an inactive 31 kDa pro-form, cut to a 17 kDa alarm: interleukin-1β.

Slide · in production

The Messenger Made Long

Left, the made-long form: PRO-IL-1β, a bar of 269 amino acids (about 31 kDa) — a prodomain (residues 1–116) and the future messenger (117–269) — drawn as a paper airplane still attached to its sheet: built, folded, unable to fly. Center, the cut: an inflammasome ring activates CASPASE-1, a protease named for what it does (a cysteine-dependent protease that cuts after aspartate), which cuts after aspartate 116; out comes MATURE IL-1β, 153 amino acids, about 17 kDa — the plane flying. A lock icon on the cell’s ER–Golgi export route: NO SIGNAL PEPTIDE — it leaves another way (why: Module 3.4). Right, the landing: the IL-1 RECEPTOR on a target cell — in the brain’s blood vessels, COX-2 switches on and PGE₂ resets the hypothalamic set point (Chapter 4; Module 1’s 1.5) — and beside it IL-1Ra, the body’s own receptor blocker, sitting in the seat so the messenger cannot land (1.5’s brake). Lecture line: a cytokine is a small signaling protein; this one is the endogenous pyrogen, the fever messenger, and it is built locked.

Explore · in production

Cut it right

A pro-IL-1β bar 269 residues long sits on a cutting board, its prodomain hatched and its messenger half plain, with three possible cut points marked by small flags (after residue 27, after residue 116, and in the middle of the messenger half near residue 200). A tool rack holds three cutters, each a labeled card: TRYPSIN (a gut enzyme that cuts after many lysines and arginines), CASPASE-1 (switched on by an inflammasome) and HEAT (a burner). Before each cut, the student predicts what will come off the board. TRYPSIN chops the bar into a pile of useless fragments — “wrong tool: digests, doesn’t activate.” HEAT unfolds it — “denatured, not activated” (a callback to Chapter 5). CASPASE-1 at the residue-27 flag makes a slightly shorter pro-form that is still inactive; CASPASE-1 at the residue-116 flag releases the 153-amino-acid, 17 kDa messenger, which lights up: the right enzyme at the right bond. Round 2, the exit: the messenger tries the cell’s usual export lane (ER → Golgi → vesicle) and a gate stays shut with the note “no signal peptide — Module 3.4 shows the other way out.” A side door opens instead, labeled “leaves through pores and unconventional routes.” Round 3, the landing: an IL-1 receptor sits on a target cell. Drop the messenger on it and a relay lights (COX-2 → PGE₂ → the hypothalamic set point rises: a fever). Reset, then drop IL-1Ra on the receptor first and try again — the messenger bounces off; the set point holds. A note: a drug copy of IL-1Ra exists and is one way FMF is treated when colchicine isn’t enough (forward to A&P II). The reveal card: a cell that builds its most dangerous alarm locked, needs one specific enzyme to unlock it, and keeps a blocker in the bloodstream has three separate brakes — and the narrator notes that pyrin sits upstream of the second one. Keyboard path: Tab to a tool, Enter to pick it up, Tab to a flag, Enter to cut; the receptor and blocker are buttons; a live region narrates each result. A <details> text version gives every tool-and-site outcome as a list.

Prefer the full lecture? Immunity: Barriers, Fever and Inflammation (original video on the site)

Think · not graded

Interleukin-1β is made long — a 31 kDa pro-form that does nothing — and only one enzyme, caspase-1, cuts it into the 17 kDa messenger. Why might a cell build its most dangerous alarm locked? And if the body already makes its own blocker, IL-1Ra, what would you expect a drug copy of that blocker to do to a fever driven by IL-1β — and to a fever driven by an infection?

The true/false spot-check for this prompt is in production.

Check · Single Choice

A neutrophil is full of pro-IL-1β, but no fever follows. What step is missing?

This self-scoring check is in production.

Evidence card 3

Add it to your evidence board

Fever came with the attacks — 103 at eleven, 102 at twelve — and no infection was ever found to explain it.

Scene 4 of 5

The Liver Answers

IL-6 calls, the liver answers: CRP, SAA, fibrinogen up, albumin down — and how to tell a signal from an error.

Animation · in production · 2 min 15 s

The Liver Answers

An inflamed belly lining glows; small envelopes labeled IL-6, IL-1β and TNF ride the bloodstream to a liver (A0109) and drop into a hepatocyte’s inbox. Production lines start: C-REACTIVE PROTEIN rolls out as five identical pieces snapping into a ring (PENTRAXIN), grabbing a phosphocholine tag on a damaged cell; a clock above it reads RISES IN 6–8 h · PEAKS ~48 h · HALF-LIFE ~19 h. SERUM AMYLOID A pours out in a flood — UP TO ~1,000× IN A DAY OR TWO — and climbs aboard HDL particles. FIBRINOGEN rises; in a glass tube beside it red cells stack like coins and fall faster: ESR = A TEST, NOT A PROTEIN. The ALBUMIN line slows: NEGATIVE ACUTE-PHASE PROTEIN. A strike-through corrects a sticky note, “CRP is a product of complement” → MADE BY THE LIVER. Two graphs: one marker rising and falling with each attack (STARTS AND STOPS); one never returning to baseline (NEVER STOPS). Two cards flip: LAB ERROR — doesn’t reproduce, doesn’t fit the picture, gone on a repeat draw / ACUTE-PHASE SIGNAL — reproducible, cytokine-driven, persists because the driver persists. Last, a chart page stamped LIKELY LAB ERROR · PROBABLY STRESS, and a tag: CHART CLUE #2 — NAMED, NOT YET LOGGED.

Prefer the full lecture? Immunity: Antimicrobial Proteins (original video on the site)

Explore · in production

The liver’s order board

A hepatocyte drawn as an order desk with an inbox and four production meters — CRP, SAA, FIBRINOGEN and ALBUMIN — each above its own line graph on a shared seven-day clock, with the textbook reference range shaded and labeled as such (CRP below about 5 mg/L; SAA below about 6–10 mg/L; fibrinogen about 200–400 mg/dL; albumin 3.5–5.0 g/dL). Order slips arrive in the inbox — IL-6 (the main caller), IL-1β and TNF — and the student can send them in or hold them back. Round 1, ONE ATTACK: predict each meter’s shape, then run a three-day attack. CRP climbs within hours, peaks near day two and drops fast once the orders stop (half-life about 19 hours); SAA rockets up to a thousand-fold and falls almost as fast; fibrinogen rises over days and lingers; albumin dips slowly and comes back slowly (its half-life is about three weeks). An ESR tube on the desk shows red cells stacking into coin-piles and settling faster as fibrinogen climbs, with the label “a test, not a protein.” Round 2, SMOLDER: the orders never fully stop between attacks — a trickle of IL-6 continues — and the student watches CRP and SAA fail to return to baseline while albumin stays a little low. The graph labels write themselves: “A marker that comes down between episodes describes something that starts and stops. A marker that never comes down describes something that never stops.” Round 3, LAB ERROR OR SIGNAL?: three illustrative patients (labeled “teaching cases, not Stina”), each with three draws plotted on the clock. Patient A: one high CRP from a hemolyzed sample, normal on the repeat the next morning. Patient B: high during an attack, normal two weeks later. Patient C: high on three draws months apart, including a week the patient called a good one, with albumin drifting low. The student runs a checklist on each — does it reproduce? does it fit the clinical picture? is there a driver? — and labels it error, starts-and-stops, or never-stops. A closing panel puts the chart’s undated row beside Patient C with no numbers on it: “Across these years: inflammatory markers high even in her good weeks. ‘Likely lab error.’ ‘Probably stress.’” and a note that SAA was a research test in 1987, so the row cannot be a childhood ER draw. Keyboard path: Tab to each order slip and Enter to send it; the clock has play, pause and step buttons; each graph is also a data table; a live region reads meter changes. A <details> text version describes every curve and the three teaching cases in words.

Think · not graded

CRP has a half-life of about nineteen hours. If an attack ends on a Sunday and CRP is drawn the following Friday, what would you expect it to be — and what would it mean if it were still high? Write the one sentence that separates a lab error from an acute-phase signal, then use it on the chart’s “Likely lab error.”

The true/false spot-check for this prompt is in production.

Check · Single Choice

Why is a CRP that stays high on repeat draws, months apart and in good weeks too, evidence rather than error?

This self-scoring check is in production.

Evidence card 4

Add it to your evidence board

Across these years: inflammatory markers high “even in her good weeks” — filed as “Likely lab error” and “Probably stress.”

Scene 5 of 5

An Alkaloid, Not a Protein

A small plant molecule from the autumn crocus: the treatment that was older than the girl.

Slide · in production

An Alkaloid, Not a Protein

Left, a pale purple autumn crocus — Colchicum autumnale, which flowers in fall on a bare stalk and is not a true crocus (the saffron crocus is a different, harmless plant; foragers have been poisoned mistaking colchicum’s spring leaves for wild garlic). Beside it, colchicine’s skeletal formula: three rings — a trimethoxyphenyl ring, a seven-membered ring carrying the nitrogen of an acetamide group, and a tropolone ring — C₂₂H₂₅NO₆, about 399 daltons. Label: ALKALOID — a nitrogen-containing compound made by a plant (caffeine, nicotine and morphine are alkaloids too). Center, a scale bar: colchicine beside a 17,000-dalton IL-1β and an 86,000-dalton pyrin, a pebble beside boulders. Right, a white cell with radiating microtubules (A3919): colchicine binds tubulin, the building block of microtubules, and stops new ones assembling — so neutrophils move and organize their alarm poorly (the target: Modules 3.3 and 3.7). Footer: THE STANDARD FMF TREATMENT SINCE THE EARLY 1970s (Goldfinger, 1972) · PREVENTS AA AMYLOID (Zemer et al., 1986) · A NARROW MARGIN BETWEEN DOSE AND POISON. A small tablet icon (A1135) with a forward tag: “Autumn crocus” — 2026.

Explore · in production

Passport control

A cell membrane drawn as a border checkpoint — a phospholipid bilayer with an oily middle lane — and five travelers in a queue, each holding a passport: COLCHICINE (about 399 Da; a plant alkaloid; uncharged; fat-soluble enough), INSULIN (about 5,800 Da; a protein hormone; charged surface), IL-1β (17,000 Da; a protein; charged surface), GLUCOSE (180 Da; small but very polar) and CHOLESTEROL (about 387 Da; almost entirely oily). Three stamps at the desk: SIZE, CHARGE and OIL-OR-WATER. Before each traveler steps up, the student predicts CROSSES ALONE, NEEDS A DOOR, or KNOCKS AND WAITS. Colchicine crosses alone into the cytoplasm; once inside it finds tubulin, and a microtubule that was growing stops (“the target: Module 3.3; why that calms the alarm: 3.7”). Cholesterol slips into the oily lane and stays in the membrane — and a note reminds the student that in blood it travels in lipoprotein parcels (Chapter 4). Glucose is small but too polar for the oily lane; a labeled door (a GLUT carrier, Module 3) opens for it. Insulin and IL-1β are too big and too charged: they knock on receptors at the surface and their messages go in without them (“this is why a protein drug is injected — swallowed, it would be digested like any other protein”). Round 2, the bouncer: an exit pump labeled P-GLYCOPROTEIN stands at the back door and throws some colchicine back out of the cell; the student slides a control that blocks the pump (“some antibiotics and other drugs do this”) and watches colchicine pile up inside past a red line on a dose meter — the narrow margin between treatment and poison, and a preview of Module 3.6. A side card says why the class matters: a protein messenger must act from outside, while a small alkaloid can reach the machinery inside, which is why a pill from a flower can quiet an alarm built of proteins. The closing card: colchicine had been the standard FMF treatment since the early 1970s — by 1987, about fifteen years. Keyboard path: Tab to the next traveler, then one of three prediction buttons, then Enter to stamp; the pump-blocker is a slider with arrow-key steps; a live region narrates each crossing. A <details> text version lists each traveler’s passport and outcome.

Prefer the full lecture? Lipids (original video on the site)

Think · not graded

Colchicine was the standard FMF treatment by the early 1970s, and it is a small, fat-soluble plant alkaloid. Insulin and IL-1β are proteins. Which of the three could you swallow and have reach the inside of a white cell, and why — size, charge, or what the gut does to proteins? Then explain why a pill can quiet an alarm that is made entirely of proteins.

The true/false spot-check for this prompt is in production.

Check · Single Choice

What kind of molecule is colchicine?

This self-scoring check is in production.

Evidence card 5

Add it to your evidence board

“We don’t go to the doctor anymore unless it’s the emergency room”: at eleven, no doctor is following the attacks at all — in years when the treatment for this disease had been in use since 1972.

4

Your evidence board

Every scene gave you an evidence card, and the chart adds more. Sort each card into the column it supports: A cast of molecules at work, unmeasured, Neither on its own, or Adjustment reaction to parental illness. Some cards can honestly go in more than one place — that’s allowed, and the feedback tells you which cards decide the case.

Evidence board · drag and drop · in production

The sorting board for this chapter’s cards is being built. Until it arrives, sort your evidence cards on paper into the three columns above.

5

Your verdict

Time to decide. Look back at your bet, then build your verdict from statements that hold up — no writing needed.

Look back at your prediction

A fever of 102, “blood and X-ray and nothing,” and “adjustment” on the pad — read through the cast, the reading that fits best is…

Find the one you chose at the top. Does the evidence support it, refute it, or revise it?

  • That there was nothing to find — “Adjustment reaction to parental illness”
  • That the blood was right but misread — “Likely lab error”
  • That the tests ordered could not see most of the molecules doing the work

Build your verdict · no writing

Choose the statement that holds in each set. The ones you keep become your argument.

This activity is in production.

6

The finding

Finding · the cast

The Cast Nobody in the Room Could See

1985–87, ages ten to twelve: a move, a fever calendar lost “in a box somewhere,” and at twelve a second ER — a fever of 102, “blood and X-ray and nothing,” and “adjustment” on a psychiatrist’s pad. Across these years: inflammatory markers high even in her good weeks — “Likely lab error,” “Probably stress.” Chart entry: the molecules of an attack belong to classes you can now name — a sensor, a messenger and the liver’s acute-phase proteins are proteins, the fever signal is lipid-derived, the treatment is a plant alkaloid; a 1987 laboratory could count ions, sugar, cells, total protein, albumin and the ESR, could have run a CRP, and could not measure serum amyloid A, interleukin-1β or pyrin; the treatment had existed for fifteen years. Held open: whether markers that never came down were error or evidence, and what a protein that comes apart and stacks has to do with them — Chapter 7 logs Chart Clue #2.

Next · Chapter 7

Misfolding: From Pyrin to Amyloid

Ten: “I want my disease to have a name.” Twelve: “If you cry, they write down that you cried.” Two kinds of wrong shape — a sensor that fires too easily and a protein that comes apart and stacks — and Chart Clue #2, logged.

Continue to Chapter 7 →

Reliable information on rare diseases

NORD · NIH GARD · Orphanet · MedlinePlus Genetics: FMF · FMF & AID Global Association · Autoinflammatory Alliance · Global Genes · Amyloidosis Foundation

Stina has one rare disease. In the United States, about 1 in 10 people live with one of the more than 7,000 known rare diseases. These organizations are where patients, families and clinicians go for trustworthy information.

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← Familial Mediterranean Fever — case home

All pages for Module 2 — Just Enough Chemistry

2.0 Module Overview
2.1 Atoms, Ions, Electrolytes
2.2 Water, pH and the Buffer
2.3 Carbohydrates and Energy
2.4 Lipids: Membranes, Steroids and the Lipoprotein Fleet
2.5 Proteins: Shape Is Everything
2.6 The FMF Molecule Cast
2.7 Misfolding: From Pyrin to Amyloid
2.8 Conclusion and Assessment
2.9 Evidence Behind the Case

All Modules
  1. Anatomical Language, Membranes & Homeostasis
  2. Just Enough Chemistry
  3. The Cell & Its Transport
  4. Making Cells & Proteins
  5. The Integumentary System
  6. The Skeletal System
  7. The Muscular System
  8. Nervous Tissue & the Senses
  9. The Spinal Cord
  10. The Brain & the Blood–Brain Barrier
  11. The Autonomic Nervous System
  12. Special Senses (in development)
  13. The Endocrine System
  14. Blood
  15. The Heart
  16. Blood Vessels
  17. The Digestive System
  18. The Respiratory System
  19. The Urinary System
  20. Fluids, Electrolytes & Acid–Base Balance
  21. The Reproductive System
  22. The Immune System

List of terms