Anaphase II

Definition

Anaphase II is the stage in meiosis where the sister chromatids are finally separated and pulled toward opposite poles of the cell. This phase follows metaphase II and is crucial for ensuring that each daughter cell receives an equal and correct number of chromosomes during gamete formation. It plays a key role in genetic diversity as it occurs after the exchange of genetic material during meiosis I.

5 Must Know Facts For Your Next Test

1. During anaphase II, the centromeres that hold sister chromatids together split, allowing them to move to opposite sides of the cell.
2. Anaphase II is characterized by the movement of chromosomes toward the poles, which is facilitated by spindle fibers attached to the kinetochores.
3. This phase ensures that each resulting gamete will have one copy of each chromosome, maintaining genetic stability.
4. Anaphase II occurs after a second round of division, following meiosis I, where homologous chromosomes are separated.
5. Errors during anaphase II can lead to conditions like aneuploidy, where gametes have abnormal numbers of chromosomes.

Review Questions

• How does anaphase II contribute to genetic diversity in gametes?
  • Anaphase II contributes to genetic diversity by separating sister chromatids, ensuring that each gamete receives a unique set of chromosomes. This process occurs after meiosis I, where homologous chromosomes undergo recombination, resulting in genetic variation. The separation during anaphase II further enhances this diversity, as it allows for different combinations of alleles to be distributed into gametes.
• What are the consequences if anaphase II does not occur properly during meiosis?
  • If anaphase II does not occur correctly, it can lead to errors such as nondisjunction, where sister chromatids fail to separate and both are pulled to one pole. This can result in gametes with an abnormal number of chromosomes, potentially leading to genetic disorders like Down syndrome or Turner syndrome when such gametes participate in fertilization. Proper functioning of anaphase II is essential for maintaining chromosomal stability in offspring.
• Evaluate the role of spindle fibers during anaphase II and how they ensure accurate chromosome segregation.
  • Spindle fibers play a critical role during anaphase II by connecting to the kinetochores on each sister chromatid and exerting forces that pull them apart toward opposite poles of the cell. This tension ensures that each daughter cell receives an equal and complete set of chromosomes. If spindle fibers malfunction or are improperly attached, it could result in unequal distribution of chromosomes, leading to genetic imbalances in the resulting gametes.

Related terms

Meiosis: A specialized form of cell division that reduces the chromosome number by half, resulting in the formation of four genetically distinct gametes.

Sister Chromatids: Identical copies of a chromosome that are connected by a centromere, which are separated during anaphase II.

Metaphase II: The stage in meiosis where chromosomes align at the cell's equatorial plane before being separated in anaphase II.