Mitosis vs. Meiosis

Definition

Mitosis and meiosis are two distinct processes of cell division that serve different purposes in living organisms. Mitosis is responsible for growth, tissue repair, and asexual reproduction, producing two identical daughter cells, while meiosis is the specialized division that creates gametes (sperm and eggs), resulting in four genetically diverse cells. Understanding these processes is crucial for grasping how genetic information is passed on and how organisms develop.

5 Must Know Facts For Your Next Test

1. Mitosis consists of several phases: prophase, metaphase, anaphase, telophase, followed by cytokinesis, while meiosis includes two rounds of division: meiosis I and meiosis II.
2. In mitosis, the daughter cells are genetically identical to the parent cell, while meiosis produces genetically diverse gametes due to crossing over and independent assortment.
3. Mitosis occurs in somatic (body) cells for growth and repair, whereas meiosis occurs only in germ cells to produce gametes for sexual reproduction.
4. Meiosis results in four haploid cells with half the chromosome number of the original cell, compared to mitosis which results in two diploid cells.
5. Errors in mitosis can lead to cancer due to uncontrolled cell division, while errors in meiosis can result in genetic disorders such as Down syndrome.

Review Questions

• Compare and contrast the phases of mitosis and meiosis, explaining their significance in cell division.
  • Mitosis involves a single round of division with phases including prophase, metaphase, anaphase, telophase, and cytokinesis. Each phase plays a crucial role in ensuring that the two resulting daughter cells are identical to the original cell. In contrast, meiosis consists of two rounds of division: meiosis I and meiosis II. Meiosis I reduces the chromosome number by half through separation of homologous chromosomes, while meiosis II separates sister chromatids. This difference is vital for producing genetic diversity in gametes.
• Discuss how genetic diversity is achieved during meiosis compared to the uniformity seen in mitosis.
  • Genetic diversity during meiosis is achieved primarily through two mechanisms: crossing over and independent assortment. During prophase I of meiosis, homologous chromosomes exchange genetic material in a process called crossing over. This creates new combinations of alleles. Additionally, during metaphase I, the arrangement of homologous pairs on the metaphase plate leads to independent assortment, where different combinations of maternal and paternal chromosomes are segregated into gametes. In contrast, mitosis produces genetically identical cells because there is no exchange or reassortment of genetic material.
• Evaluate the implications of errors occurring during mitosis or meiosis on human health and development.
  • Errors during mitosis can lead to conditions such as cancer, where unregulated cell division results in tumors. This can happen due to mutations that disrupt normal checkpoints in the cell cycle. In contrast, mistakes during meiosis can lead to aneuploidy or genetic disorders; for example, Down syndrome occurs when there is an extra copy of chromosome 21 due to nondisjunction. Such errors highlight the importance of precise cell division mechanisms for maintaining genetic stability and proper development.

Related terms

Chromosomes: Structures made of DNA and proteins that contain the genetic information of an organism, which are duplicated and segregated during mitosis and meiosis.

Gametes: Reproductive cells produced through meiosis that have half the number of chromosomes, essential for sexual reproduction.

Cytokinesis: The process that occurs after mitosis or meiosis where the cytoplasm divides, resulting in the separation of the daughter cells.