Definition

Noun: * In cell biology, a chromatid is one of the two identical, thread-like strands that make up a duplicated chromosome. These two sister chromatids are joined together at a region called the centromere. During cell division (mitosis or meiosis II), the chromatids separate and move to opposite poles of the cell, ensuring each new daughter cell receives an identical copy of the genetic material.

Usage

• The term is used specifically in the context of genetics and cell division to describe the structure and behavior of chromosomes during the process of replication and segregation.
• It is a countable noun (e.g., , ).

Examples

• Before cell division, each chromosome consists of two identical chromatids.
• The spindle fibers attach to the centromere of each chromatid.
• During anaphase, the sister chromatids are pulled apart.

Advanced Usage

• Sister Chromatids: This is the most common and precise usage, referring to the two identical chromatids produced by chromosome replication. They are held together by cohesin proteins.
• Non-sister Chromatids: In the context of meiosis, this refers to chromatids on homologous chromosomes (one from the mother, one from the father) that may exchange genetic material during crossing over.

Variants and Related Words

• Chromosome (noun): The structure that carries genetic information, composed of DNA and proteins. A chromosome is to form two sister chromatids.
• Centromere (noun): The specialized region of a chromosome where the two sister chromatids are most closely attached and where spindle fibers bind.
• Mitosis (noun): The type of cell division in which sister chromatids separate to form two genetically identical daughter nuclei.
• Meiosis (noun): The type of cell division that reduces the chromosome number by half, producing gametes (sperm and eggs). Chromatid separation occurs during meiosis II.

Synonyms

• Chromosome strand: A more general descriptive term.
• Sister chromatid: The most specific and accurate synonym when referring to one of the two identical copies.

Notes on Meaning

The word chromatid has a single, highly specific meaning in biology. It does not have different general meanings, idioms, or phrasal verbs. Its entire definition is tied to its role in the structure of a duplicated chromosome during cell division.

Noun

1. one of two identical strands into which a chromosome splits during mitosis