Download Instructor`s Copy - I Like Your Genes

Instructor’s Copy
Lab Worksheet: I Like Your Genes
Use the diagrams provided by your teacher to help you complete the following data table.
Data varies by class.
Trait
Dominant Recessive
Possible genotypes
Class
dominant
Class
recessive
PTC taster
Tongue roller
Ear lobes
Dimples
Freckles
Hair whorl
Widow’s peak
Handedness
Finger length
Eye color
Nearsightedness
Hair color
Hitchhiker’s thumb
Folding hands
Little finger
Eyelashes
Darwin’s ear point
Hairy joint
QUESTIONS:
1. Did you show more dominant or recessive traits? Individual answer, make sure it is backed up
by the student’s data.
2. Did your class show more dominant or recessive traits? Varies, make sure it is backed up by the
student’s data.
3. If you show the dominant trait, is it possible for you to determine your exact genotype? No
4. Explain your answer to number 3. Can’t tell if you are homozygous dominant (AA) or
heterozygous (Aa)
5. If you show the recessive trait, is it possible for you to determine your exact genotype? Yes
6. Explain your answer to number 5. Have to be aa, this is the only way a recessive trait shows up.
7. Is it possible for you to show a trait that is present in your grandparents even if your parents do not
show the trait? Yes
8. Explain your answer to number 7. It could be carried recessively in your parents, and both
recessives matched up in you so the trait was expressed.
9. If more males than females show a trait, it may be because the trait is passed on the X
chromosome. What is the name for this type of trait? Sex-linked trait.
10. Some scientists are trying to show that a person’s ability to taste PTC paper may determine why
those same people don’t like certain types of food like brussel sprouts. How is this possible?
Whether dominant or recessive, if the gene is present, it would make you taste something
nasty where someone without the trait would not taste it.