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MODULE 4:
MAKING CELLS AND PROTEINS
PART 6 OF 7
Learning the mutation traced back to a single original cell hit her hardest. “It was in me before I was born,” she said — not something she caught, or caused, or could ever have avoided.
Slide 1 Transcript
PATIENT CHART
STINA
Serositis, Pleural effusion, Self-limiting fever episodes
THIS PART
Age 30
PRESENTING WITH
Culture negative, self-limited fevers with serositis
ACTION TAKEN
Pharmacological
DRUGS ORDERED
Colchicine
CHART CLUES
COLLECTED AS YOU GO
A Full Family & Ancestry History
A Germline (Constitutional) Variant
An Actively Expressed Disease
MEFV Mutation, Misfolded Pyrin
It’s the Sequence, Not Damage
?
?
Put your money down: How does one typo end up in sixty trillion cells?
Bet before the divisions begin. Stina found it baffling that one illness could surface in so many unrelated places — it seemed like far too many problems to be one problem. Two quick fact-checks on mitosis; then the ask: does that scatter mean several separate conditions — or one gene copied into every cell from the very first?
Pick the answer you believe now. We’ll come back to it later!
Too Many Problems to Be One Problem
Of everything Stina learned, the part that landed hardest was also the part that finally lifted the blame. The mutationA change in DNA sequence that can affect gene function., she was told, traced all the way back to a single original cell; it had been inside her before she was born. “Not something I caught, or caused, or could have avoided,” she said, turning the idea over slowly. For years some private part of her had wondered whether she had done this to herself — too much stress, the wrong foods, not enough rest, some failure she could not name. Learning that the error predated her very first breath did not make her well, but it did set down a weight she had been carrying for a long time.
Cash out the clip
Single Choice: What are the two main jobs of mitosis in the body?
The Four Phases
Watch three things to tell them apart — prophaseThe first stage of mitosis where chromatin condenses into visible chromosomes., metaphaseA stage of mitosis where chromosomes align at the metaphase plate., anaphaseA stage in mitosis or meiosis where sister chromatids or homologous chromosomes separate., telophaseThe final stage of mitosis where nuclear envelopes reform around separated chromosomes..
Slide 3 Transcript
Cash out the clip
Drag the Words: Drop each event into its mitosis phase.
From One Cell to Trillions
Cells reproduce on a schedule called the cell cycleThe sequence of events in a cell’s life, including growth, DNA replication, and division.. During interphaseThe phase of the cell cycle in which the cell grows, performs its functions, and replicates DNA. a cell grows (G1), copies all of its DNA in S phaseThe DNA synthesis phase of the cell cycle where chromosomes are replicated., and prepares to divide (G2); then M phase splits it into two. Checkpoints stand guard between the steps, pausing the cycle to inspect for damage and, if something is badly wrong, triggering apoptosisProgrammed cell death, an essential process for growth and development. so that broken cells do not divide. It is a quality-control system of real rigor, designed to keep errors from propagating.
When Sorting Fails
Nondisjunction — chromosomes that won’t separate, so daughter cells miscount.
Slide 4 Transcript
Cash out the clip
Fill in the Blanks: Fill in what nondisjunction is and what it causes.
One Cell to Trillions
Every cell, the same instruction — from the zygote, faithful copies, differentiation hands out the jobs.
Slide 5 Transcript
Cash out the clip
Mark the Words: Mark what mitosis preserves from the zygote onward.
One Gene, Every Room of the House
And here is the quiet heartbreak of Stina’s case: her error is not the kind of damage the checkpoints are built to catch. It is woven into the legitimate sequence itself, indistinguishable from a correct instruction. So every time one of her cells passed through S phase, the typo was duplicated along with everything else, and every checkpoint waved it through as perfectly normal. A flawless quality-control process, faithfully copying a flaw it was never designed to recognize. The system worked exactly as intended — which is precisely why it never saved her.
FINDING!
A Single Multisystem Disorder
The scattered picture — belly one year, chest another, a joint, then the bloodwork — was never many diseases. Mitosis copied one MEFV typo from the zygote into every one of her ~60 trillion cells, and differentiation simply gave those cells different jobs. Chart entry: a single multisystem genetic disorder explains the serositis, arthritis, and inflammatory markers together — one gene, present in every room of the house, not a coincidental pile-up of unrelated problems.
Confirm or refute your bet: How does one typo end up in sixty trillion cells?
Having watched mitosis sort a complete, identical chromosome set into each daughter cell from the zygote onward, return to the bet. The same typo was copied into every cell, and differentiation made those cells into skin, gut, joint lining, and neutrophils — tissues nothing alike, all carrying the same flawed gene.
Slide 8 Transcript
NEXT PART
If every division copies the typo, what happens when you zoom out to a whole human being? Next we follow mitosis from one fertilized egg to trillions of cells — every one of them carrying MEFV.
QUICK QUESTIONS
QUICK QUESTIONS
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← Familial Mediterranean Fever — case home
All pages for Module 4 — Making Cells & Proteins
4.0 Module Overview
4.1 The First Doctor Who Asked
4.2 Copying the Code
4.3 Written in Me the Whole Time
4.4 One Letter — Translation and M694V
4.5 It Was in Me Before I Was Born — The Cell Cycle
4.6 One Typo, Every Cell
4.7 The Reveal – From MEFV to Diagnosis
4.8 Conclusion and Assessment
4.9 Evidence Behind the Case
All Modules
- Anatomical Language, Membranes & Homeostasis
- Just Enough Chemistry
- The Cell & Its Transport
- Making Cells & Proteins
- The Integumentary System
- The Skeletal System
- The Muscular System
- Nervous Tissue & the Senses
- The Spinal Cord
- The Brain & the Blood–Brain Barrier
- The Autonomic Nervous System
- Special Senses (in developmentThe process of growth and differentiation.)
- The Endocrine System
- Blood
- The Heart
- Blood Vessels
- The Digestive System
- The Respiratory System
- The Urinary System
- Fluids, Electrolytes & Acid–Base Balance
- The Reproductive System
- The Immune System
List of terms
- mutation
- growth
- skin
- cells
- prophase
- metaphase
- anaphase
- telophase
- cell cycle
- interphase
- S phase
- apoptosis
- development