Discuss how genes are related to chromosomes. 2. Differentiate between somatic cells & gametes, haploid & diploid, homologous chromosomes, and sex chromosomes & autosomes. 3. Describe the structure of DNA and chromosomes during the cell cycle including terminology such as chromatin, sister chromatids, and centromere. 4. Correlate the timing of mitosis within the cell cycle. 5. Identify and describe the major events of mitosis & meiosis. 6. Compare and contrast both the functions and the events in mitosis & meiosis. 7. Describe the differences in meiosis that contribute to spermatogenesis and oogenesis. 8. Discuss how meiosis leads to genetic diversity (crossing over & independent assortment). 9. Explain how mistakes can happen in meiosis and how they affect human health. 10. Interpret karyotypes as male, female, or affected by Downʼs Syndrome (Trisomy 21).
A. Mitosis and Meiosis are two different types of cell division with different functions. B. Mitosis occurs for growth and repair while meiosis only occurs to make gametes. C. There are 46 chromosomes in somatic cells (23 homologous pairs) and 23 chromosomes in gametes. Keeping the number of chromosomes at 46 in somatic cells is necessary. D. The cell cycle involves periods of growth, preparation for division, and mitosis. E. Mitosis: interphase, prophase, metaphase, anaphase, telophase, cytokinesis. F. After mitosis, cells have 46 chromosomes, 23 pairs (diploid) G. Meiosis: NOT the same as mitosis, two sets of division. After meiosis, cells have 23 chromosomes, haploid. The chromosomes move differently during the two divisions. H. Meiosis is important for keeping the number of chromosomes constant in our population and increasing genetic diversity. I. There are two ways that meiosis increases genetic diversity: crossing over is the exchange of pieces of one chromosome for pieces of another; random assortment is the random alignment and distribution of chromosomes at the midline and following the two divisions. J. Meiosis in males occurs throughout adulthood. Meiosis in females begins before birth and only completes after fertilization. K. If meiosis does not occur properly, it can lead to an extra chromosome or no chromosome to be present in a gamete and can lead to genetic conditions like Downʼs Syndrome, Klinefelter, or Turner Syndrome