Sister chromatid

Definition

Sister chromatids are identical copies of a single chromosome, created during DNA replication prior to cell division. They are crucial for ensuring that each new daughter cell receives an exact copy of the genetic material during cell division processes like mitosis and meiosis. Each sister chromatid is connected at a region called the centromere, which plays an essential role during the segregation of chromosomes.

5 Must Know Facts For Your Next Test

1. Sister chromatids are formed during the S phase of interphase when DNA is replicated.
2. Each sister chromatid contains the same genetic information and is crucial for maintaining genetic consistency during cell division.
3. During mitosis, sister chromatids separate at the centromere and move to opposite poles of the cell to ensure equal distribution to daughter cells.
4. In meiosis, sister chromatids undergo separation in both meiosis I and meiosis II, contributing to genetic diversity through processes like crossing over.
5. Mistakes in the separation of sister chromatids can lead to aneuploidy, where daughter cells have an abnormal number of chromosomes, which can cause genetic disorders.

Review Questions

• How do sister chromatids contribute to genetic stability during cell division?
  • Sister chromatids play a vital role in maintaining genetic stability by ensuring that each daughter cell receives an exact copy of the genetic material. During DNA replication, each chromosome is duplicated into two identical sister chromatids, which remain connected at the centromere. When the cell undergoes division, these chromatids are pulled apart and distributed equally, minimizing the risk of genetic mutations or variations that could occur if chromosomes were not accurately segregated.
• Discuss the importance of sister chromatids in both mitosis and meiosis and how their roles differ in these processes.
  • In mitosis, sister chromatids are essential for producing two identical daughter cells, as they ensure that each new cell has the same set of chromosomes as the original. The chromatids separate during anaphase, moving to opposite ends of the cell. In contrast, meiosis involves two rounds of division where sister chromatids first separate during meiosis II. This process leads to genetic diversity in gametes due to independent assortment and crossing over events, highlighting their different roles in these two forms of cell division.
• Evaluate the consequences of improper separation of sister chromatids during cell division and its potential impact on human health.
  • Improper separation of sister chromatids can result in aneuploidy, where daughter cells end up with an abnormal number of chromosomes. This condition can lead to various genetic disorders, such as Down syndrome, which is caused by an extra copy of chromosome 21. Other potential health impacts include cancer, where errors in chromatid segregation contribute to tumorigenesis by creating cells with unbalanced chromosome numbers. Understanding these consequences underscores the critical importance of accurate chromatid separation during cell division.

Related terms

Chromosome: A structure composed of DNA and proteins that carries genetic information in the form of genes.

Mitosis: A type of cell division that results in two genetically identical daughter cells from a single parent cell.

Meiosis: A specialized form of cell division that reduces the chromosome number by half, producing four genetically diverse gametes.