Anaphase II

Definition

Anaphase II is a stage in meiosis that follows metaphase II, where the sister chromatids of each chromosome are pulled apart toward opposite poles of the cell. This separation is crucial for reducing the chromosome number in gametes, ensuring that each daughter cell receives a haploid set of chromosomes. Anaphase II occurs after the alignment of chromosomes at the metaphase plate and is essential for genetic diversity and proper chromosomal distribution in sexual reproduction.

5 Must Know Facts For Your Next Test

1. Anaphase II is characterized by the separation of sister chromatids, which ensures that each gamete receives only one copy of each chromosome.
2. This stage occurs after meiosis I and follows a similar process as mitotic anaphase, highlighting the similarities and differences between these two forms of cell division.
3. Anaphase II contributes to genetic variation by allowing for independent assortment and potential crossing over events that can occur during meiosis I.
4. The process is facilitated by spindle fibers that connect to the centromeres of sister chromatids, pulling them toward opposite poles.
5. Errors during anaphase II can lead to aneuploidy, which is an abnormal number of chromosomes in gametes, potentially resulting in genetic disorders.

Review Questions

• How does anaphase II differ from anaphase in mitosis, and what are the implications for genetic diversity?
  • Anaphase II differs from anaphase in mitosis primarily in that it involves the separation of sister chromatids rather than homologous chromosomes. In mitosis, sister chromatids are pulled apart to ensure that each daughter cell receives a complete set of chromosomes. In contrast, during anaphase II of meiosis, the focus is on separating chromatids in haploid cells, which contributes to genetic diversity through independent assortment and potential recombination events that occur earlier in meiosis.
• What role do spindle fibers play during anaphase II, and how does their function affect chromosomal distribution?
  • Spindle fibers play a critical role during anaphase II by attaching to the centromeres of sister chromatids and facilitating their movement toward opposite poles of the cell. As these fibers contract, they pull the chromatids apart, ensuring that each pole receives an equal and accurate distribution of genetic material. This movement is essential for producing gametes with the correct haploid number of chromosomes, which is crucial for successful fertilization and development.
• Evaluate the consequences of errors occurring during anaphase II on human reproduction and genetic outcomes.
  • Errors during anaphase II can lead to aneuploidy, where gametes end up with an abnormal number of chromosomes. This can have significant consequences in human reproduction, potentially leading to conditions like Down syndrome or Turner syndrome when such gametes participate in fertilization. The impact on genetic outcomes highlights the importance of precise chromosomal movements during this phase to ensure healthy development and viable offspring.

Related terms

Meiosis: A type of cell division that reduces the chromosome number by half, resulting in four genetically diverse haploid cells from one diploid cell.

Sister Chromatids:

Identical copies of a chromosome that are connected by a centromere and are separated during anaphase II.

Gametes: Reproductive cells (sperm and eggs) that are produced through meiosis and carry half the genetic information of an organism.