9. Mitosis and Meiosis

Describe the organization of the interphase nucleus. Include in your presentation a description of chromosome territories, interchromatin compartments, and transcription factories.

If two chromosomes of a species are the same length and have similar centromere placements and yet are not homologous, what is different about them?

Describe the events that characterize each stage of mitosis.

How are chromosomes named on the basis of their centromere placement?

Contrast telophase in plant and animal mitosis.

Describe the phases of the cell cycle and the events that characterize each phase.

The nuclear DNA content of a single sperm cell in Drosophila melanogaster is approximately 0.18 picogram. What would be the expected nuclear DNA content of a primary spermatocyte in Drosophila? What would be the expected nuclear DNA content of a somatic cell (non-sex cell) in the G1 phase? What would be the expected nuclear DNA content of a somatic cell at metaphase?

Contrast the chromatin fiber with the mitotic chromosome. How are the two structures related?

Describe the 'folded-fiber' model of the mitotic chromosome.

You are given a metaphase chromosome preparation (a slide) from an unknown organism that contains 12 chromosomes. Two that are clearly smaller than the rest appear identical in length and centromere placement. Describe all that you can about these chromosomes.

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?