Anaphase

Definition

Anaphase is a stage in cell division where the sister chromatids of each chromosome are pulled apart and moved towards opposite poles of the cell. This critical phase ensures that each daughter cell will receive an identical set of chromosomes, contributing to genetic stability during cell division. Anaphase occurs following metaphase and is crucial in both mitosis and meiosis, facilitating accurate chromosome segregation.

5 Must Know Facts For Your Next Test

1. During anaphase, enzymes break down the proteins holding sister chromatids together at the centromere, allowing them to separate.
2. Anaphase can be divided into two parts: anaphase A, where chromatids are pulled apart, and anaphase B, where the poles of the cell move further apart.
3. The proper progression through anaphase is regulated by the spindle assembly checkpoint, ensuring that all chromosomes are attached to spindle fibers before separation.
4. Mistakes during anaphase can lead to aneuploidy, a condition where daughter cells have an abnormal number of chromosomes, potentially leading to diseases like cancer.
5. Anaphase in meiosis is slightly different; it involves the separation of homologous chromosomes in meiosis I and sister chromatids in meiosis II.

Review Questions

• How does anaphase contribute to the accuracy of chromosome segregation during cell division?
  • Anaphase plays a vital role in ensuring that sister chromatids are pulled apart and distributed evenly to each daughter cell. The separation occurs after the chromatids are aligned at the metaphase plate, which helps prevent errors in distribution. If anaphase proceeds correctly, each resulting daughter cell receives an identical set of chromosomes, maintaining genetic stability.
• Discuss the regulatory mechanisms that control the transition into anaphase and their importance.
  • The transition into anaphase is tightly controlled by the spindle assembly checkpoint, which ensures that all chromosomes are properly attached to spindle fibers before separation begins. This regulation is crucial as it prevents premature separation, which could lead to unequal distribution of chromosomes. If any chromosome is not correctly aligned or attached, the checkpoint delays the onset of anaphase until issues are resolved, safeguarding against chromosomal abnormalities.
• Evaluate the consequences of errors occurring during anaphase on cellular health and organism development.
  • Errors during anaphase can result in aneuploidy, where daughter cells end up with an incorrect number of chromosomes. This can lead to various health issues, including genetic disorders such as Down syndrome or contribute to the development of cancer through uncontrolled cell division. Additionally, these chromosomal abnormalities can affect organism development significantly, leading to developmental disorders or infertility due to improper gamete formation.

Related terms

Chromatid: One half of a duplicated chromosome, which is joined to its sister chromatid by a centromere.

Centromere:

The region of a chromosome where two sister chromatids are joined and where the spindle fibers attach during cell division.

Spindle Fibers: Microtubule structures that help separate the chromosomes during cell division by attaching to the centromeres of chromosomes.