Hopanoids

Definition

Hopanoids are pentacyclic triterpenoids found in the membranes of many bacteria. They play a role similar to sterols in eukaryotic cells, contributing to membrane stability and functionality.

5 Must Know Facts For Your Next Test

1. They help stabilize bacterial cell membranes by filling gaps between fatty acid chains.
2. Hopanoids are structurally similar to sterols like cholesterol found in eukaryotic cells.
3. They can be used as biomarkers in geological studies due to their durability over geological timescales.
4. The presence of hopanoids can increase the rigidity and decrease the permeability of bacterial membranes.
5. Bacteria such as cyanobacteria and methanotrophs commonly produce hopanoids.

Review Questions

• What is the primary function of hopanoids in bacterial cell membranes?
• In what way are hopanoids similar to sterols found in eukaryotic cells?
• Why are hopanoids useful as biomarkers in geological studies?

Related terms

Sterols:

A group of lipids that include cholesterol, which stabilize cell membranes in eukaryotes.

Triterpenoids: A class of chemical compounds composed of three terpene units with potential biological activity.

Cyanobacteria:

A phylum of bacteria that obtain their energy through photosynthesis and often produce hopanoids.