This chapter introduces two types of cell divisions. First, it explains mitosis and then meiosis. This chapter also explains why cells divide and how the divisions are regulated. The errors in the division may lead to diseases, such as leukemia.
- 7.1: Case Study: Genetic Similarities and Differences
- This introduces the concept of mitosis and meiosis in the form of a Leukemia case study.
- 7.2: Cell Cycle and Cell Division
- Cell division is the process in which one cell, called the parent cell, divides to form two new cells, referred to as daughter cells. How this happens depends on whether the cell is prokaryotic or eukaryotic. Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells themselves are simpler. Prokaryotic cells have a single circular chromosome, no nucleus, and few other organelles. Eukaryotic cells, in contrast, have multiple chromosomes contained within a nucleus.
- 7.3: Mitotic Phase - Mitosis and Cytokinesis
- The process in which the nucleus of a eukaryotic cell divides is called mitosis. During mitosis, the two sister chromatids that make up each chromosome separate from each other and move to opposite poles of the cell. This is shown in the figure below. Mitosis actually occurs in four phases: prophase, metaphase, anaphase, and telophase.
- 7.4: Mutations and Cancer
- Your cells may grow and divide without performing their necessary functions, or without fully replicating their DNA, or without copying their organelles. Probably not much good could come of that. So the cell cycle needs to be highly regulated and tightly controlled. And it is.
- 7.5: Sexual Reproduction: Meiosis and gametogenesis
- Whereas asexual reproduction produces genetically identical clones, sexual reproduction produces genetically diverse individuals. Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. As both parents contribute half of the new organism's genetic material, the offspring will have traits of both parents, but will not be exactly like either parent.
- 7.6: Genetic Variation
- Genetic variation. It is this variation that is the essence of evolution. Without genetic differences among individuals, "survival of the fittest" would not be likely. Either all survive, or all perish.
- 7.7: Mitosis vs. Meiosis and Disorders
- Both mitosis and meiosis result in eukaryotic cells dividing. So what is the difference between mitosis and meiosis? The primary difference is the differing goals of each process. The goal of mitosis is to produce two daughter cells that are genetically identical to the parent cell, meaning the new cells have exactly the same DNA as the parent cell. Mitosis happens when you want to grow, for example. You want all your new cells to have the same DNA as the previous cells.
- 7.8: Case Study Genes Conclusion and Chapter Summary
- Humans are much more genetically similar to each other than they are different.
Thumbnail: Image of the mitotic spindle in a human cell showing microtubules in green, chromosomes (DNA) in blue, and kinetochores in red. Image used with permission (Public Domain; Afunguy).