Chromatids

Definition

One of the two identical, thread-like DNA molecules that result from chromosome replication and remain joined at the centromere until they separate during cell division; each chromatid becomes an independent daughter chromosome upon anaphase separation.

Etymology

From Greek chroma (color) + -id (diminutive suffix), referring to their stainability with basic dyes.

Example

In the ovarian tissue of a grasshopper, each replicated chromosome consists of two sister chromatids held together at the centromere; during meiosis I, homologous chromosomes pair while sister chromatids remain attached, ensuring proper segregation of genetic material into gametes.

Synonyms

• sister chromatids
• daughter chromatids

Related Terms

• Chromosome
• Centromere
• kinetochore
• Mitosis
• Meiosis
• anaphase
• DNA replication
• cell cycle

Usage Notes

The term 'sister chromatids' specifically denotes the two identical copies derived from the same chromosome; 'non-sister chromatids' refers to chromatids from homologous chromosomes. Chromatids are transient structures, existing only from S phase through metaphase until they separate and are thereafter termed individual chromosomes. In cytogenetic studies of insects and other arthropods with holocentric chromosomes (e.g., some Lepidoptera, Hemiptera), chromatid behavior differs as centromere activity is distributed along the chromosome length.