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Saturday, March 26, 2005

Wired News: Mendel's Law May Be Flawed

Wired News: Mendel's Law May Be Flawed:
Challenging a scientific law of inheritance that has stood for 150 years, scientists say plants sometimes select better bits of DNA in order to develop normally even when their predecessors carried genetic flaws...

...In the experiment, the Purdue researchers found that 10 percent of watercress plants with two copies of a mutant gene called "hothead" didn't always blossom with deformed flowers like their parents, which carried the mutant genes. Instead, those plants had normal white flowers like their grandparents, which didn't carry the hothead gene and the deformity appeared only for a single generation.

This is truly ground breaking. I still remember being taught that certain genetic traits such as albinism can only be expressed if the person has 2 copies of that albino gene i.e. the gene is recessive (dominant genes only need 1 copy to be expressed). That's why certain genetic traits may skip a generation or more because the child did not receive recessive genes from both mum and dad.

The devil's advocate in me then asked what if Mendel's theory still holds fully? What if there's an activation gene that plays a role in the expression of the "hothead" gene? Both "hothead" gene could be passed down to the child but the parents might not have passed down this activation gene, in which case, the "hothead" gene would not show up in the child. But I'm no geneticist, so I digress!

Here's a picture of the flowers of the mutant watercrest plant with the "hothead" gene. The Purdue news articledescribes the flowers as "fused into tight balls". Now compare that with the "hothead" gene expressed in humans on the right. Looks to be fused into a tight ball as well. I guess if there's hope for the watercrest, there's hope for us too!



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