Collins Lab Blog

Intracellular anatomy – the modern definition of organelle

Organelle: diminutive of Latin organum or organ, literally a “little organ of the cell”.

What defines an organelle? What distinguishes an entity being defined as an organelle as oppose to a macromolecular machine?

Is is a question of scale?

Is it a question of general functional relevance to a cell?

Is it a question of compartmentalization?

Is it a question of the ability to self-replicate or renew?

Are organelles autonomous or non-autonomous?

Do we think of organelles as constant entities in the lifetime of a cell or constant entities throughout the cell cycle?

Is it a distinction that is useful for teaching cell biology?

The image below shows a picture of the proteosome from a cryo-electron microscopy, taken from Nickell, S. et al. Insights into the molecular architecture of the 26S proteasome. Proc. Natl. Acad. Sci. USA 106, 11943–11947 (2009).

The dimensions of the Drosophila 26S proteosome shown here are about 12 nm across and roughly 45 nm in length.

Is the proteosome an organelle or a macromolecular machine?

Please fill out the poll and let me know your opinion.

9/12/11 UPDATE:

Overwhelming response supports the opinion that the proteosome is NOT an organelle, rather it is a supra-molecular assembly or apparatus.

Thanks to all who voted!

 

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