Cyst

Definition

A cyst is a dormant, resistant form of a unicellular eukaryotic organism that helps it survive harsh conditions. Cysts are often part of the life cycle of parasitic protozoa and can be involved in transmission to new hosts.

5 Must Know Facts For Your Next Test

1. Cysts allow parasitic protozoa to survive outside the host in unfavorable environmental conditions.
2. Infections like giardiasis and amebiasis often involve cysts as a key stage in their transmission.
3. Cysts are typically resistant to desiccation, heat, and chemicals, making them difficult to eliminate.
4. In the context of skin and eye infections, cysts can be introduced through contact with contaminated water or surfaces.
5. The formation of cysts is a crucial adaptation for the survival and spread of parasitic protozoa.

Review Questions

• What role do cysts play in the life cycle of parasitic protozoa?
• How do cysts contribute to the transmission of diseases like giardiasis and amebiasis?
• Why are cysts resistant to harsh environmental conditions?

Related terms

Trophozoite:

The active, feeding stage of a protozoan life cycle.

Encystment: The process by which a trophozoite becomes a cyst.

Excystation:

The process by which a cyst transforms back into an active trophozoite.