Category Archives: Numbers / Scales

Intuiting Biological Scales using Human Scales

Figure 1. Human Scale Key: Aircraft Carrier (200m), 3-story House (20m), Human (2m), Liver/Gerbil (200mm), Lymph Node/Mosquito (20mm), Skin/Flee (2mm), Hair thickness (200um)
Biological Scale Key: Flee (2mm), Amoeba (200um), Eukaryotic Cell (20um), Mitochondria/Bacteria (2um), Centriol/Large Virus (200nm), Cell Membrane/Small Virus (20nm), dsDNA thickness (2nm)

The length scale of molecular and cellular biology (Figure 1 Biological Scales) covers approximately 5 orders of magnitude, with sizes ranging from 1 nanometer (approximate size of small molecules) to 100 micrometers (approximate size of the largest cells). Unfortunately, it can be difficult to intuit these relative sizes because we cannot directly observe these scales.

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