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Figure 2.1:(Icons.)Dramatis personæ.Approximate relative sizes of some of the actors in our story. T2 phage
is a virus that infects bacteria, for exampleEscherichia coli.Much of this book will be occupied with phenomena
relevant at length scales from the protozoan down to the DNA helix. [Copyrighted figure; permission pending.]
Figure 2.2:(Drawing, based on light microscopy.) Relative sizes (1000×magnification). (a)FiveEscherichia coli
bacteria cells (enlarged in Figure 2.3). (b)Twocells of baker’s yeast. (c)Human red blood cell. (d)Human white
blood cell (lymphocyte). (e)Human sperm cell. (f)Human epidermal (skin) cell. (g)Human striated muscle cell
(myofibril). (h)Human nerve cell. [From (Goodsell, 1993).] [Copyrighted figure; permission pending.]
avery long answer, of course. Among the many physical ideas relevant to this question, however,
three will dominate this chapter and the rest of the book:
Biological question:How do cells organize their myriad ongoing chemical processes and reactants?
Physical idea:(a)Bilayer membranesself-assemblefrom their component molecules; the cell uses