W chromosome
- Pronunciation
- /duh-buhl-yoo KROH-muh-sohm/
- Category
- Genetics
- Singular
- W chromosome
- Plural
- W chromosomes
Definition
A sex-determining chromosome found in certain insect species, particularly Lepidoptera (moths and butterflies), where females are the heterogametic sex (ZW) and males are the homogametic sex (ZZ). The W chromosome is specific to females and plays a role in female development.
Etymology
The term 'chromosome' is derived from the Greek 'chroma', meaning 'color', and 'soma', meaning 'body', referring to the stained appearance of chromosomes under light microscopy. The letter 'W' was chosen to distinguish it from the 'X', 'Y', and 'Z' chromosomes in other sex-determination systems.
Example
In the silkworm moth (Bombyx mori), females have one Z chromosome and one W chromosome, while males have two Z chromosomes.
Related Terms
- Z chromosome
- Sex determination
- Genetic inheritance
- Sex chromosomes
- Lepidoptera
Usage Notes
In entomology, the W chromosome is particularly important in studying sex determination and inheritance patterns in Lepidoptera and some other insect orders. Unlike the XY system found in Drosophila and many other insects, the ZW system in Lepidoptera has the female as the heterogametic sex. The W chromosome is often smaller and gene-poor compared to the Z chromosome.