For Problems 25–30, consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., A^m and A^p). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis. You may wish to use a large piece of brown manila wrapping paper or a cut-up paper grocery bag for this project and to work in partnership with another student. We recommend cooperative learning as an efficacious way to develop the skills you will need for solving the problems presented throughout this text. In mitosis, what chromatid combination(s) will be present during metaphase? What combination(s) will be present at each pole at the completion of anaphase?

Key Concepts

Mitosis

Mitosis is a type of cell division that results in two genetically identical daughter cells, each with the same number of chromosomes as the original cell. It consists of several phases: prophase, metaphase, anaphase, and telophase. During metaphase, chromosomes align at the cell's equatorial plane, and during anaphase, sister chromatids are pulled apart to opposite poles. Understanding these phases is crucial for analyzing chromatid combinations at different stages.

Chromatid Pairing

Chromatid pairing occurs when chromosomes replicate during the S phase of the cell cycle, resulting in two identical sister chromatids for each chromosome. In diploid cells, these chromatids consist of one maternal and one paternal chromatid. During metaphase of mitosis, these paired chromatids align at the metaphase plate, and their separation during anaphase ensures that each daughter cell receives an identical set of chromosomes.

Chromosome Segregation

Chromosome segregation is the process by which chromosomes are distributed into daughter cells during cell division. In mitosis, this occurs during anaphase when the sister chromatids are pulled apart to opposite poles of the cell. Proper segregation is essential for maintaining genetic stability, as errors can lead to aneuploidy, where daughter cells have an abnormal number of chromosomes. Understanding this concept is vital for predicting chromatid combinations at the end of mitosis.