At a Glance

One set of recipes, read differently; much of what decides sits outside the book.

1. Part 1The larva keeps its cookbook; its food decides if it becomes a queen.
2. Part 3Copies are made and thrown away, so a body changes what it makes within hours.
3. Part 4A liver cell and a nerve cell keep the same cookbook and serve different dishes.
4. Part 5Smoking or a move shifts the caps, not the recipes.

A gene can go quiet, or a protein go wrong, without one letter changing.

1. Part 1The yeast still had the recipe. The price of wormwood decided.
2. Part 2Many stuttering tumors have MLH1 silenced by caps, not a typo.
3. Part 3A vaccine's copy is broken down; your DNA stays untouched.
4. Part 4Some folds go wrong with every letter in place: the cooked egg, the prion.
5. Part 5Off is not gone: a cap silences a gene, every letter unchanged.

The cell reads a wrong letter as its own; where it lands decides the harm.

1. Part 1One changed letter keeps lactase on for life.
2. Part 2A missed slip stays put, and the cell reads it as if it were right.
3. Part 4One letter makes sickle cell.

DNA to RNA to protein is the usual road. It can bend, and control loops back.

1. Part 3RNA back to DNA was one of Crick's "special transfers"; HIV uses it.
2. Part 4A prion copies a fold, not a sequence, so Crick's rule holds.
3. Part 5A protein decides which DNA gets read: control runs back up the chain.

A result is only as good as what the test looked for, and when.

1. Part 1What did the test look for? Which people was it built on?
2. Part 2A stutter does not always mean an inherited break; a blood test settles it.
3. Part 3Ask whether SMA is on your state's newborn screen.
4. Part 5Whether the caps shifted before the diabetes or after, one blood draw cannot say.