phenylthiocarbamide

A chemical substance that is either intensely bitter to some people or tasteless to others. This ability to taste PTC appears to have a genetic basis.

PTC is also an abbreviation for phenylthiocarbamide which is a crystalline compound with the formula C₆H₅NHCSNH₂ As described in the node hitchhiker's thumb it is often used in Biology classes to illustrate the genetic transmission of the ability to taste the compound within a family. Unfortunately:

• It has not been approved by the FDA.
• It is described as a rodenticide in Sax's Dangerous Properties of Industrial Materials (DPIM)
• According to the Merck Index, the lethal dose for rats is 40 mg/kg of body mass.

The teacher hands out strips of paper. They're white and look the size of shredded paper. You put it on your tongue. Taste anything?

If you have the dominant gene, you can taste the bitter/sour taste. If you can't, you have 2 recessive genes so you can't taste it. Lemme start over.

The paper is soaked in phenylthiocarbamide, PTC. If you have the gene from one of your parents, you can taste it. If you don't have the gene from either parent, you can't taste it, only the paper. Nothing big, no big deal, just another thing, like hitchhiker's thumb or mid-digital hair.

This is more common than the other genetic taste test, sodium benzoate.