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# Long description

The figure consists of two parts, Figures 2a and b, that illustrate the relative sizes of various structures (cells, organelles and molecules).

Figure 2a: a horizontal logarithmic scale shows the size range of various structures. The scale has the following markings from left to right: 1 centimetre, 1 millimetre, 100 micrometres, 10 micrometres, 1 micrometre, 100 nanometres, 10 nanometres, 1 nanometre and 0.1 nanometres.

Size range visible using a light microscope (ranging from approximately 2 millimetres to 400 nanometres) for the following structures is shown.

Plant cells (a typical plant cell with a central nucleus, mitochondria, chloroplasts, endoplasmic reticulum, ribosomes, cell wall and cell membrane): approximately 1 millimetre to 20 micrometres.

Animal cells (a typical animal cell with a nucleus, mitochondria, endoplasmic reticulum, ribosomes and cell membrane): approximately 150 micrometres to 6 micrometres.

Most bacteria (rod-shaped, spherical, chain of spherical cells): approximately 10 micrometres to 800 nanometres.

Chloroplasts and mitochondria (organelles): approximately 5 micrometres to 1 micrometre.

Figure 2b: the size range visible using the electron microscope (ranging from approximately 100 nanometres to 0.125 nanometres) for the following structures is shown.

Viruses (composed of a polyhedral head, a short collar and a helical tail): approximately 50 to 500 nanometres.

Ribosomes (three ribosomes): approximately 25 nanometres.

Cell membrane (phospholipid bilayer; each layer composed of a spherical hydrophilic head with a pair of hydrophobic tails): approximately 7.5 nanometres.

ATP (a central pentagonal ring bound to a fused ring (hexagon fused to a pentagon) on the upper left and a chain of three circles indicating phosphates on the upper right): approximately 2 nanometres.

Glucose (a chain of four hexagonal rings): approximately 0.9 nanometres.

X: structure for which the size should be read by the student.