Polytene Chromosomes

Definition

Giant, transversely banded chromosomes found in certain tissues of Diptera and some other arthropods, formed by multiple rounds of replication without separation, resulting in a bundle of chromatids aligned side by side.

Etymology

From Greek 'poly-', meaning 'many', and '-tene', from 'tainia', meaning 'band' or 'ribbon'.

Example

Polytene chromosomes are best developed in tissues with high secretory activity, such as the salivary glands of Drosophila.

Synonyms

• Giant chromosomes

Related Terms

• Diptera
• Chromosomes
• Salivary gland chromosomes

Usage Notes

The banding patterns of polytene chromosomes can be used to study genetic variation and gene regulation.