Julie Ann Miller

A matter of taste

Have you ever tried the jelly bean test? It’s an experiment that proves the importance of the nose in the sense we call “taste.” Hold your nose closed and put a jelly bean or some other fruitflavored candy in your mouth. Chew the candy. You’ll taste sweetness and maybe a little sourness but not much else. Then open your nose. Suddenly, you’ll get the full force of the fruit flavor. Chewing releases molecules, which are groups of atoms stuck together, in the candy. In the mouth, these molecules trigger basic tastes: sweet, salty, sour, and bitter. Odor molecules also float from the back of the mouth up into the nose.

Mammals need moms and dads

Although a mammalian offspring receives from each parent what appear microscopically to be equivalent chromosomes (except for the sex chromosomes in males), experiments on mice indicate that there are subtle but crucial differences in this inheritance. Biologists are now working to determine how the maternal or paternal origin is imprinted on a chromosome and how subsequent development processes are differentially influenced. Recently developed techniques allow scientists great freedom in altering the genetic constitution of eggs and the resulting embryos.