Chromatid

Definition

A chromatid is one half of a duplicated chromosome, which consists of two identical copies known as sister chromatids. These sister chromatids are connected at a region called the centromere and play a crucial role during cell division, specifically in ensuring that genetic material is accurately distributed to daughter cells. The process of chromosome duplication and separation of chromatids is vital for maintaining genetic continuity across generations of cells.

5 Must Know Facts For Your Next Test

1. Sister chromatids are formed during the S phase of the cell cycle when DNA is replicated, resulting in two identical copies of each chromosome.
2. During mitosis, sister chromatids are pulled apart by spindle fibers to opposite poles of the dividing cell, ensuring each daughter cell receives an identical set of chromosomes.
3. The number of chromatids present in a cell depends on its stage in the cell cycle; a diploid cell has 92 chromatids after DNA replication, before mitosis begins.
4. Chromatids can also undergo genetic recombination during meiosis, leading to genetic diversity in gametes.
5. Disorders such as aneuploidy can occur if chromatids do not separate properly during cell division, leading to cells with abnormal numbers of chromosomes.

Review Questions

• How do chromatids ensure genetic accuracy during cell division?
  • Chromatids ensure genetic accuracy during cell division by allowing for the precise replication and distribution of genetic material. During mitosis, sister chromatids are separated at the centromere and pulled toward opposite poles of the cell by spindle fibers. This separation is crucial because it guarantees that each daughter cell receives an exact copy of the genetic information, maintaining genetic stability across generations.
• Discuss the role of the centromere in chromatid function during mitosis.
  • The centromere plays a pivotal role in chromatid function during mitosis by serving as the attachment point for spindle fibers. When the cell enters mitosis, spindle fibers connect to the centromeres of each chromatid pair, allowing them to align at the metaphase plate. Once aligned, the centromeres facilitate the separation of sister chromatids during anaphase, ensuring that each daughter cell receives the correct number of chromosomes.
• Evaluate the consequences of improper chromatid separation during meiosis.
  • Improper chromatid separation during meiosis can lead to significant consequences such as aneuploidy, where gametes contain an abnormal number of chromosomes. This can result in conditions like Down syndrome or Turner syndrome if such gametes participate in fertilization. The failure to separate chromatids correctly not only affects individual offspring but also contributes to broader population genetics by influencing genetic variation and evolutionary processes.

Related terms

Chromosome: A structure composed of DNA and proteins that carries genetic information; each chromosome consists of two chromatids during cell division.

Centromere:

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

Mitosis: The process of cell division that results in two genetically identical daughter cells, involving the separation of sister chromatids.