Microbiology Demystified

Here’s Looking at You

The principal way a microbiologist studies microorganisms is by observing them
through a microscope. Amicroscopeis a device that enlarges objects using a
process called magnification. The simplest form of a microscope is a magnify-
ing glass consisting of a single lens that is shaped in such a way as to make
things appear larger than they are to the naked eye. And the simplest magnify-
ing glass is the bottom of an empty glass. Some glasses are slightly bent at the
bottom, causing a magnifying effect if held at a certain height over an object.
This causes a change in the ray’s path.
The most complex microscope is an electron microscope, which uses elec-
trons to increase the apparent size of an object. Electron microscopes are capa-
ble of magnifying the organs of a microorganism called organelles, which you’ll
learn about later in this book. That is, an electron microscope is capable of show-
ing what is inside a bacterium and virus.

WAVELENGTH

You don’t really “see” anything. It sounds strange, but it is true. You see only the
reflection of light waves—or, in the case of an electron microscope, the reflec-
tion or absence of electrons. Electromagnetic radiation is generated by a variety

CHAPTER 3 Observing Microorganisms^51

10m 1m 0.1m 1cm 1mm 100μm10μm1μm 100nm 10nm 1nm 0.1nm

Electron Microscope

Light Microscope

Unaided Human Eye

Human Frog

Egg

Bacteria VirusesProteins Atom

Lipids

Chicken

Egg

Fig. 3-1. Comparative sizes of humans and microorganisms.