BIOL 111 Predicting the Outcome of a Monohybrid Cross Discussion

Activity B: Predicting the Outcome of a Monohybrid Cross.

The Punnett square was devised to keep track of all possible combinations of genotypes when more than one type of gamete can be produced Fill out the Punnett square in Figure 91 for the F generation by crossing offspring of the previous cross (Rr X Rr)

R r

R RR Rr

r Rr rr

Figure 1: Fine 9.1: Punnett square for monohybrid cross

1. What are the possible genotypes in the F2 generation?

2. What is the phenotype of each genotype in the F2 generation?

3. What is the phenotypic ratio for the cross?

Activity C: The Chromosomal Basis of Independent Assortment

In Figure 9.2 below is a cell that represents the following conditions: diploid two homologous pairs of chromosomes, two unlinked genes called R and A cell is heterozygous for both genes.

R is the gene for tongue-rolling, as used in the previous examples A determines arch characteristics.

A person who has the dominant allele has normal arches. An individual who is homozygous recessive has flat feet.

1. What is the genotype of this cell?

2. What is the phenotype of the individual represented by the cell in figure 9.2?

3. Recall that when this cell undergoes meiosis, each gamete receives one member of each homologous pair. List the possible combinations of alleles that will be found in the games

4. In what proportion would you expect these gametes to occur?