Classroom Set
The Genetic Wheel – Genetics Introduction
Standard: Genetics 2e
Obectives:
 Students will distinguish their genetic traits with their classmates.
 Students will be able to identify and interpret their own phenotypes (physical traits).
Instructions: In this activity you will observe 7 common traits of the human population. Dominance is the most
common trait in a population and in the lab is expressed with a capital letter. Recessive traits
1. Use the GENETIC WHEEL and place your finger in the MIDDLE of the circle (blank) either L_ or ll
2. Identify your hair color with the chart below, and move your finger from the middle of the circle to either L_ or ll
3. Proceed to the second trait and figure out your hair type, from your original answer you will move either to T_ or
tt.
4. Continue this process for all 7 traits.
5. When finished you will have a special student number #.
Teacher should demonstrate each trait 
Table 1. Trait, Genotypes, and Variations
Trait
Phenotype
Genotype
1. Hair color
brown, black, or red hair
LL or Ll
blond hair
ll
naturally curly
TT or Tt
naturally straight
tt
can curl tongue
CC or Cc
cannot curl tongue
cc
hair present, middle digit of finger
MM or Mm
hair absent, middle digit of finger
mm
eyes not blue
EE or Ee
blue eyes
ee
peak in center of hairline
WW or Ww
no peak in center of hairline
ww
little finger curves toward others
BB or Bb
little finger straight
bb
2. Hair type
Refer to the GENETIC WHEEL
(back of paper) when finished
identifying your traits.
3. Tongue curling
4. Mid-digital hair
5. Pigmented iris
6. Widow's peak
7. Bent finger
Background: October 2004 findings from The International Human Genome Sequencing Consortium, led in the United
States by the National Human Genome Research Institute (NHGRI) and the Department of Energy (DOE), reduce the
estimated number of human protein-coding genes from 35,000 to only 20,000-25,000, a surprisingly low number for our
species (Stein, L. D. 2004. "Human Genome: End of the Beginning," Nature 431, 915-916.). In this lab we will identify 7
protein-coded genes.
Classroom Set
The Genetic Wheel – Genetics Introduction
Student # ?
Classroom Set
The Genetic Wheel – Genetics Introduction
Teacher Key
Teacher - Whiteboard
1. Follow and assist students through the instructions on the
classroom handout.
2. Create a basic table on the whiteboard to collect data about
the student #’s.
0-20
21-40
41-60
61-80 81-100 101-128
Collect
student
data here
3. When the class finishes your instructor can call out 0-20 and
you will raise your hand. Continue this with 21-40, 41-60,
61-80, and so on. Students will get to identify classmates
who share common traits with them and class data can be
collected.
4. If time allows, have the most common student #’s with the 7
traits stand in front of the class to demonstrate the 7 traits.
This allows for possible errors to be identified and corrected.
5. Additional traits can be introduced to slowly eliminate members from the front of the room (i.e.;
Interlaced Fingers- Left thumb over right Dominant, Hitch Hiker’s Thumb Dominant, Free Hanging
earlobes Dominant, Face dimples Dominant, and long eyelashes Dominant).
Last 15 minutes of class.
6. PTC Paper TEST (Phenylthiocarbamide, also known as PTC, or phenylthiourea) Give students
control and PTC strips without telling them what the strips are. Have the class taste the strips and report
on their results on whether or not they can or cannot taste the PTC. Generate discussion about why some
people can taste and others cannot.
a. The ability to taste is dominant and is controlled by a single gene. Students can also take strips
home and test family members. Then they can make pedigrees of the inheritance of this trait and
see its dominant pattern of inheritance. There are also other types of strips available for tasting.
The PTC activity can also be used in conjunction with scoring other genetic traits, such as
tongue-rolling and widow’s peak.
b. After tasting the paper, students can remove the taste of PTC by having a drink of water or
sucking on a hard candy.
c. Continue the discussion about PTC paper onto the following class day.