Nucleotide metabolism

Why this matters

This is the lesson where the dentist becomes the treatment. The drugs that block nucleotide synthesis announce themselves in the mouth before anywhere else, the antiviral you prescribe for a cold sore works by a trick of nucleotide chemistry, and the lower lip you examine at every recall is where pyrimidines are damaged by sunlight. One inherited disease in this topic is managed principally by a dentist.

The big picture

Nucleotides are built the expensive way or recycled the cheap way, and destroyed down two very different drains — purines to insoluble uric acid, pyrimidines to soluble waste. Almost every drug in this lesson works by jamming one of those routes, and almost every consequence you will see appears in the mouth, because oral epithelium divides faster than anything else you can look at.

The 14 cards in this lesson

1. 01Two rings, one ring, one phosphate
2. 02Four jobs before they are ever DNA
3. 03Build, recycle, destroy — and where the drugs bite
4. 04Opposites at both ends
5. 05Methotrexate: the mouth is the alarm bell
6. 06Clinical alert — in the lesson
7. 07Aciclovir, and the reason to push fluids
8. 08The lower lip is a photochemistry lesion
9. 09Three genes, three drugs, three mouths
10. 10Clinical alert — in the lesson
11. 11One molecule, two crystals
12. 12Gout in your chair: what changes, what doesn't
13. 13The purines you drink, and what they don't do
14. 14When the dentist is the treatment

You have got it when

You are ready to continue when you can convert a urate value without using sixty, explain why aciclovir harms the virus and not the patient, and say what you would do differently for a patient taking azathioprine.