Download EXERCISE #10. ANTHROPOSCOPY OF MENDELIAN TRAITS. 1

EXERCISE #10. ANTHROPOSCOPY OF MENDELIAN TRAITS.
1.) Some people have earlobes than hang, and some people don’t.
The gene for free hanging earlobes is dominant, and the gene for
attached earlobes is recessive. That means that you have free hanging
earlobes if you inherited the gene for it from at least one of your
parents meaning that your genotype is “EE” (both genes for freehanging lobes) or “Ee” (one gene for free hanging lobes). However,
you have attached earlobes if you inherited genes from both parents
that give instructions for attached lobes (“ee”).
2.)
2) Darwin’s Point. Darwin's Tubercle (as seen in the picture
above and below) is a cartilaginous node or bump on the outer
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rim of the ear, or helix. During about the sixth week of
development, a number of small cellular bumps called the
Hillocks of Hiss, which give rise to the ear canal, fuse together
forming a tubercle. The current hypothesis is that the tubercle
is a vestige of a joint which allowed our ancestral ear to swivel or
cover the ear canal. It got its name from Darwin in the opening
of the Descent of Man comparing the point and a group of nonfunctional ear muscles in humans that are homologous to
primates used to focus on directional sounds.
3.)
The trait itself is kind of rare. It's only seen in approximately 10% of the
population. Besides being non-functional, and causing no harm, the
Tubercle's genetics are really interesting as well. The gene(s) that cause the
trait follow an autosomal dominant pattern of expression.
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3) Tongue Rolling. The ability to roll the tongue sideways is dominant over
no tongue-rolling.
4) Dry or Wet ear wax. But it has long been noted that there are 2 types of
ear wax, "wet" and "dry". Wet ear wax is common in Caucasians and
African-Americans, it tends to be honey-to-brown in color and sticky in
nature. In contrast, dry ear wax is common in East Asians and is gray in
color and more brittle and flakey. And now we know the underlying genetic
basis. wet ear wax, is a dominant trait. Individuals with dry ear wax , a
recessive trait, are homozygotes.