1.1. Cell Biology and Microscopy

Like telescopes helped astronomers reveal the vast splendor of the universe, the advent of microscopes helped us cell biologists peer into the realm of cells that had heretofore remained hidden to the naked eye. Robert Hooke is widely credited to have first observed plant cell walls in slices of cork in the 1600's. He is also credited to have coined the term “cell” to refer to the spaces between the cell walls in his famous book Micrographia (p. 116) that was published in 1665 A.D. (a digital version of this classic is available for free browsing at https://tinyurl.com/25nprv8t). His observations were followed by Antonie van Leewenhoek’s account of live cells, but the dawn of cell biology as a scientific discipline began in the 1830s. German scientists Matthias Jakob Schleiden and Theodor Schwann – the former looking at plant cells and the latter at animal cells – posited what became known as the Cell Theory, which stated that all living creatures are composed of one or more cells, and that the cell is the structural and functional unit of life.

Unlike the early light microscopes used by van Leeuwenhoek that could only magnify specimens a few hundredfold, state-of-the-art electron microscopes can magnify specimens more than a million times and can reveal the details of organelles and other sub-cellular components at the micrometer and even nanometer scale. With the development of the confocal microscope, combined with the use of Green Fluorescent Protein (GFP), the three-dimensional structure and organization of cells have been better understood in both animals and plants. I have used both electron and fluorescence microscopy to capture several images and videos in this e-book that provide vivid details of various plant cell types and organelles. From my own work, I have come to appreciate that amid the diversity of cells that compose a living organism, there are general attributes shared by all cells and that there are highly intricate functions particular to specialized cells that is often recapitulated in their form.

Mind the scale!

Do you know how many centimeters are there in a meter? How many millimeters are there in a centimeter? And how many micrometers in a millimeter? Even further, how many nanometers are there in a micrometer? Micrometer, often abbreviated as "µm" in scientific shorthand is the most common unit of scale used in biological microscopy, and that one can divide a distance of 1 millimeter into one thousand 1µm units! The Greek word "mikros" refers to anything "small", and forms the root of the first half of the word "microscope", while the word "skopein", meaning "to look at", forms the root of the latter half.