Concepts of Biology (BIOL115) - Dr. S.G. Saupe (ssaupe@csbsju.edu); Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321 |
Single
Gene Traits in Humans
The following is a list of some autosomal human traits that have been
attributed to a single gene. Although clearly other genes are involved,
the inheritance of each of these phenotypic traits acts as if it were governed by a single gene. First,
indicate your expression of the trait (i.e., circle the appropriate
phenotype). Then, indicate if you
exhibit the dominant or recessive trait (D or R?).
Finally, using any letters/symbols you want, write your genotype for the
trait (hint: if you show the
recessive trait, your genotype will be homozygous recessive (i.e., "aa").
If you exhibit the dominant trait your genotype could be homozygous
dominant (i.e., "AA") or heterozygous (i.e., "Aa").
A shorthand symbol for this is "A_").
How could you distinguish between these possibilities?
Trait |
Phenotype |
Dominant
or recessive phenotype? |
Genotype |
Tongue
Rolling (Dominant) |
roll/not roll |
|
|
Widow's
Peak (D) - just like Eddie Munster |
yes/no |
|
|
Wet
ear wax (D) - stick your finger in to check |
wet/dry |
|
|
L/R
interlocking finger (D) -
without thinking, clasp your hands together,
is the right thumb over the left, or vice versa? |
L/R
or R/L |
|
|
Attached
earlobes (D) |
yes/no |
|
|
Hitchhiker
Thumb (r) - does it bend back at a 90 angle |
yes/no |
|
|
PTC
tasting (D) - I'll have some test paper in class |
yes/no |
|
|
Chin
fissure (D) - like actor Michael Douglas |
yes/no |
|
|
Darwin
tubercle (D) |
yes/no |
|
|
S-methylthioester
detection (Recessive) -
can you smell asparagus odor in urine? |
yes/no |
|
|
Pigmented
iris (D) - any color but blue |
yes/no |
|
|
Freckles
(D) |
yes/no |
|
|
Polydactyl
(D) |
yes/no |
|
|
Dimples
(D) |
yes/no |
|
|
Wooly
hair (R) |
yes/no |
|
|
Long
eyelashes (> 1cm; D) |
yes/no |
|
|
Short
big toe (D) - the big toe is shorter than your second one |
yes/no |
|
|
Last updated: July 14, 2009
� Copyright by SG Saupe