Face / Head Variation Lab
Why are even closely related siblings different both in genotype and phenotype? They differ because the variety of traits in a human population is very large and reproduction continually creates new combinations of traits.
What traits would would a baby have at age 15 if both the student and a classmate (make-believe spouse) were heterozygous for each trait listed on the lab? Inherited traits are determined by chance. This lab illustrates that by the procedure listed below. WIth this simulation exercise, it must be kept in mind that actual inheritance is much more complicated than this exercise implies and that geneticists do not yet fully understand the process.
Procedure:
1. Pair up into make-believe sets of parents.
2. To determine the genotype for each trait, each parent will flip their own coin.
Heads indicates that the parent contributes the dominant gene represented in the descriptions by the capital letter.
Tails indicates that the parent contributes the recessive gene represented by the small letter.
3. On the data sheet, list the genes contributed by each parent, and what they are together for the genotype of the baby, and what phenotype is represented by that genotype for the baby.
Analysis Questions:
- What percent chance do you and your partner have of “producing” a male offspring? A female offspring? Explain your answer.
- Would you expect the other pairs of students in your class to have an offspring similar to yours? Explain your answer.
- If a woman who is homozygous for almond shaped eyes (AA) married a man who is heterozygous for almond shaped eyes (Aa), what are the possible genotypes and phenotypes of their children?
- What are the possible genotypes of the parents of a child who has wavy hair (Hh)?
- Which traits in this investigation showed a blending of genes?
Critical Thinking and Application:
- Did you think that anyone in your class has all the same genetic traits that you have? Explain your answer.
- How might it be possible for you to show a trait when neither of your parents shows it?
- Do you think you would have some genetic traits similar to your grandparents? Explain your answer.
- There is a small village in a mountain valley in Spain where a large number of people are polydactyl (have more than five fingers or toes). Why does this trait tend to be passed on from generation to generation?
- There have been cases in history where a king has divorced his queen because she produced only daughters. Using your knowledge of genetics, explain why this was an incorrect move.
Conclusion:
At the end of the lab, create a portrait of what your child would look like in 15 years in my Biology class.