a On chromosome 1 reside genes A and B.
i. Gene A alleles: black/white (black is dominant to white)
ii. Gene B alleles: dark blue/light blue (dark blue is dominant to light blue)
Genotype: Your organism is heterozygous for gene A and heterozygous for gene B. Assume the maternal copy of chromosome 1 has dominant alleles for both genes.
b On chromosome 2 reside genes C and D.
i. Gene C alleles: green/yellow (alleles have codominant relationship)
ii. Gene D: Red (This gene is monomorphic: it only comes in one form!)
Genotype: Your organism is heterozygous for gene C, homozygous for gene D.
c On chromosome 3 resides gene E
i. Gene E alleles: pink/purple (Pink is dominant to purple)
Genotype: Your organism is homozygous for the recessive allele
B. Modeling Mitosis and Meiosis
For #4, each person should select one pair of homologous chromosomes.
4. Model mitosis with your materials. What do the chromosomes look like in metaphase?
Share your answers for #4 in your group.
For 5, work in pairs to model meiosis for either chromosome 1 or chromosome 2.
5. Model meiosis with your materials. What are possible outcomes of crossing over for each gene? What do the chromosomes look like in Anaphase I? Metaphase II?
Share your answers for #5 in your group.
Mitosis and Meiosis Discussion Questions
1. What are homologues, sister chromatids, and bivalents? When do sister chromatids separate during mitosis? When do
sister chromatids separate during meiosis?
2. Describe the arrangement of chromosomes at metaphase of mitosis. How is this different from the arrangement of chromosomes at metaphase I of meiosis I?
3. What are the differences in the cells produced by mitosis and meiosis?
Mitosis vs. Meiosis Defining Features Matrix: Complete the following table with information about the listed feature in mitosis
Feature Mitosis Meiosis I Meiosis II
Preceded by DNA replication? (Yes/No)
When is formation of bivalents?
Crossing over during prophase? (Yes/No)
Describe alignment at metaphase plate
Describe separation at anaphase
Genetically identical daughter cells
Haploid daughter cells produced? (Yes/No)