Anonymous asked in Science & MathematicsBiology · 1 decade ago

PTC, how does the ability to taste it come to a human genetically?

My brother says that the ability to taste PTC is completely dominant. He says that if your parents taste it, then you will taste it. How the heck does an alllele like that exist?


Wouldnt it have a counter dominant/recessive trait?

2 Answers

  • 1 decade ago
    Favorite Answer

    Your brother is right and wrong. It is dominant. Having one copy will allow you to taste PTC. However, if both of the parents are heterozygous (can taste PTC), then 1/4 of their children would be unable to taste PTC.

    If I have two copies of the gene and you have one, I will have twice as many PTC taste receptors as you. However, your one copy of the gene codes for a sufficient amount of receptors to allow you to taste PTC. Therefore, we both taste PTC equally because we both have enough PTC receptors to do so. Even though I have more, it doesn't matter. We both have enough.

    Here is an example using arbitrary numbers: pretend an individual needs 40 PTC receptors to taste PTC. One copy of the PTC gene codes for 50 PTC receptors. Two copies of the gene code for 100 PTC receptors. Since both are greater than 40, both would allow for you to taste PTC.

    Does that clear it up for you?

    Source(s): Medical student.
  • 1 decade ago

    Like most other genetic attributes, Natural Selection.

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