Sterol

Definition

Sterols are a subgroup of steroids with hydroxyl groups at the 3-position of the A-ring. They play essential roles in cell membrane structure and function.

5 Must Know Facts For Your Next Test

1. Sterols are important components of eukaryotic cell membranes, providing stability and fluidity.
2. Cholesterol is a well-known sterol found in animal cell membranes.
3. Ergosterol serves a similar role to cholesterol but is found in fungal cell membranes.
4. Sterols can be precursors to biologically active molecules such as hormones and vitamins.
5. Prokaryotes generally lack sterols in their cell membranes, though some bacteria synthesize hopanoids which serve a similar function.

Review Questions

• What role do sterols play in eukaryotic cell membranes?
• Name two types of sterols and specify where they are commonly found.
• How do sterols differ between prokaryotic and eukaryotic organisms?

Related terms

Cholesterol:

A type of sterol found predominantly in animal cell membranes that helps maintain membrane fluidity.

Ergosterol:

A sterol present in fungal cell membranes that serves functions similar to cholesterol.

Hopanoids:

Lipid molecules in some bacteria that function similarly to sterols by stabilizing the cell membrane.