PART A.
In the first section of the lab, you are going to use 2 pennies to determine the alleles inherited from each parent. The first penny will represent the female (mother) and the second penny will represent the male (father). Mark one of the pennies so you know which penny represents each parent. We are going to assume that both parents are heterozygous for all traits discussed (Bb). Heads represents the dominant allele (B) and tails represents the recessive allele (b). In this section we are going to look at the presence or lack of widow's peak in humans. Widow's peak is a V-shaped point in the hairline in the center of the forehead, and is a dominant trait. Both parents have the genotype: Bb.
Based on the parents' genotypes, what is the genotypic ratio expected from a monohybrid cross between the two parents for the trait?
Based on the genotypic ratio from question 1, what is the expected probability of each genotype? (BB Bb bb) (0%25% 50% 75% 100%)
Toss the coins together 50 times and keep a tally sheet while doing so. They can only turn up as BB, Bb, or bb. Remember: each coin represents each parent and each toss can only turn up one way, therefore, a parent can give only one gene of a pair. How many tally's for each genotype did you get?
- BB
- Bb
- bb
Determine the actual probability in percent, that each genotype occurred.
- BB
- Bb
- bb