What is the Difference Between Sterol and Steroid?

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Sterols and steroids are both types of organic compounds found in living organisms, but they have distinct differences. Here are the main differences between sterols and steroids:

  • Structure: Sterols are a subgroup of steroids with a hydroxyl group at the 3-position of the A-ring. Steroids, on the other hand, have a wide variety of structures, including cholestane, cholesterol, and other modifications.
  • Function: Sterols are amphipathic lipids synthesized from acetyl-coenzyme A via the HMG-CoA reductase pathway. They occur naturally in most eukaryotes, including plants, animals, and fungi, and are vital to cell membrane structure. Steroids, which include sterols, have various functions, such as serving as precursors to sex hormones, glucocorticoids, and vitamin D.
  • Classification: Sterols are a specific type of steroid, and all sterols are steroids. However, not all steroids are sterols. Steroids encompass a broader range of compounds, including those without the hydroxyl group at the 3-position of the A-ring.

In summary, sterols are a specific subgroup of steroids, characterized by the presence of a hydroxyl group at the 3-position of the A-ring and their role in cell membrane structure. Steroids, on the other hand, are a more diverse group of compounds with various functions and structures.

Comparative Table: Sterol vs Steroid

Here is a table comparing the differences between sterols and steroids:

Feature Sterols Steroids
Definition Sterols are organic compounds derived from gonane with H #3 replaced with an alcohol (−OH) group, and are a sub-class of steroids. Steroids are biologically active compounds with a gonane core structure, which can be further modified.
Origin Sterols occur in the membranes of plants, animals, and microorganisms and are termed phytosterols, zoosterols, and mycosterols, respectively. Steroids are found in various forms, including cholesterol, sex hormones, glucocorticoids, and anabolic steroids.
Structure Sterols have the core structure of gonane with an alcohol group added to H #3. Steroids have a gonane core structure with various modifications, such as methyl groups or other attached groups.
Role Sterols are required for maintaining cell fluidity. Steroids have various biological roles, including hormone production and cell messaging.

Sterols and steroids share some similarities, as sterols are a precursor for steroids. However, they also have distinct differences, such as their structures, origins, and roles within the body.