The Cell: A Visual Tour of the Building Block of Life
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With The Cell: A Visual Tour of the Building Block of Life, Jack Challoner treats readers to a visually stunning tour of these remarkable molecular machines. Most of the living things we’re familiar with—the plants in our gardens, the animals we eat—are composed of billions or trillions of cells. Most multicellular organisms consist of many different types of cells, each highly specialized to play a particular role—from building bones or producing the pigment in flower petals to fighting disease or sensing environmental cues. But the great majority of living things on our planet exist as single cell. These cellular singletons are every bit as successful and diverse as multicellular organisms, and our very existence relies on them.
The book is an authoritative yet accessible account of what goes on inside every living cell—from building proteins and producing energy to making identical copies of themselves—and the importance of these chemical reactions both on the familiar everyday scale and on the global scale. Along the way, Challoner sheds light on many of the most intriguing questions guiding current scientific research: What special properties make stem cells so promising in the treatment of injury and disease? How and when did single-celled organisms first come together to form multicellular ones? And how might scientists soon be prepared to build on the basic principles of cell biology to build similar living cells from scratch.
ISBN-13: 9780226224183
Media Type: Hardcover
Publisher: University of Chicago Press
Publication Date: 10-16-2015
Pages: 192
Product Dimensions: 8.60(w) x 9.70(h) x 0.80(d)
Jack Challoner is the author of more than thirty books on science and technology. He also works as an independent science consultant for print, radio and TV.
A Brief History of the Cell The earliest observations of cells were made in the late seventeenth century, but their fundamental importance in the natural world only became apparent over 150 years later, in the middle of the nineteenth century. Since then, increasingly rapid strides have been taken toward understanding what goes on inside cells — and how such processes relate to growth, reproduction, inheritance, disease, and the origin of life on Earth. A whole new world When seventeenth-century natural philosophers and physicians gazed through microscopes at plants, animals and fungi they were treated to tantalizing glimpses of anatomy and physiology on tiny scales. Microscopes allowed these scientists and doctors to discover "microorganisms" — entire living things too small to see with the naked eye — and to stumble across the existence of cells. A revolution in seeing The facts surrounding the invention of the microscope are about as clear as the images that early examples of these instruments produced. It was in the 1590s, or possibly the early 1600s, and probably in Holland, but possibly in England, that someone first placed two lenses in an arrangement that produced a magnified image. What is known is that the new instrument, more powerful than the hand lenses already in use, quickly captured the imagination of natural philosophers across Europe. The magnifying power and optical quality of microscopes improved gradually during the seventeenth century. Although minerals and everyday objects were frequent subjects of study, it was closeup views of living things that really caught people's eyes. In 1660, the Italian physician Marcello Malpighi carried out microscopic studies of human flesh and found tiny blood vessels — the capillaries, which join arteries to veins. The discovery of capillaries confirmed a controversial theory: the circulation of blood, put forward by William Harvey in 1628. Malpighi studied many plants and animals with his microscopes, and in 1666, after studying a blood clot, he described "very small red particles" that "roll and turn helter-skelter", the first confirmed sighting of what we now call red blood cells. Tiny boxes The most influential microscopist of the age was Englishman Robert Hooke. While employed as "curator of experiments" at the new Royal Society in London, Hooke made many observations through microscopes and telescopes, and produced a beautifully illustrated book of what he had seen. Micrographia was published in September 1665 and its exquisite drawings and intriguing text gave readers an insight into a world hidden from everyday eyes. The now famous diarist Samuel Pepys was among those captivated, noting: "Before I went to bed, I sat up till 2 a-clock in my chamber, reading of Mr. Hooke's Microscopical Observations, the most ingenious book that I ever read in my life." It was Hooke who coined the word "cell" to describe what he saw when studying cork. He placed thin slivers of the material onto a dark plate beneath his microscope's objective lens, illuminated them with light from an oil lamp focused through a thick lens, and gazed through the eyepiece. His description of what he saw, quoted below, is still intriguing. Hooke estimated that there were about 10,000 cells to the inch (about 4,000 per centimeter) and that one cubic inch would contain about "twelve hundred millions" (about 70 million per cubic centimeter). It was an astonishing discovery; he wrote that this intricate structure was "almost incredible, did not our Microscope assure us of it by ocular demonstration." Each of Hooke's "cells" is a cube with sides measuring just over 20 microns, or 0.02 millimeters. "I could exceeding plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular ... these pores, or cells, were not very deep, but consisted of a great many little Boxes, separated out of one continued long pore, by certain Diaphragms, as is visible by the Figure B, which represents a sight of those pores split the long-ways." Animalcules Although compound microscopes (with two or more lenses) were popular during the seventeenth century, many investigators also used "simple microscopes" — just single powerful lenses. Some of these could magnify as well, if not better, than their more complicated counterparts. One man who favored single lenses was Antony van Leeuwenhoek, a successful Dutch draper. Leeuwenhoek made tiny, near-spherical lenses by melting glass rods in a flame. He carefully ground them to the right shape and attached them to ingenious handheld metal frames that also held the specimen. He investigated everything from tongues to sand and became the first person to describe sperm cells (which he found in the males of several species, including humans). While most microscopes of the time achieved magnifications of between 30x and 60x, Leeuwenhoek's could magnify more than 250x. In 1675, Leeuwenhoek observed tiny living creatures in a sample of rainwater that had been standing for a few days. These microorganisms were far, far smaller than any living things anyone had ever seen. Leeuwenhoek called them "animalcules." For the next year he studied river water, well water, and seawater, some of which he left standing for several days or weeks. Mostly, he saw protozoa and single-celled algae, which are about the same size as Hooke's cork cells — some quite a lot larger. But in April 1676 he saw animalcules that were much smaller, and these he described as being so tiny that you would need to lay more than a hundred end to end to measure the same as a grain of sand. This was almost certainly the first observation of bacteria. A letter that Leeuwenhoek wrote in 1683 contains the world's first illustrations of bacteria. The letter detailed his microscopic investigations of his own dental plaque: "I have mixed it with clean rain water, in which there were no animalcules, and I saw with great wonder that there were many very little animalcules, very prettily a-moving." Leeuwenhoek also wrote that "there are not living in our United Netherlands so many people as I carry living animals in my mouth this very day." Cell theory Surprisingly, perhaps, the idea that living things are made of cells did not come from the observations of the first microscopists, such as Hooke, Leeuwenhoek, and Malpighi. Instead, it originated as a philosophical thought borrowed from physical science. Living molecules In his influential book Philosophiæ Naturalis Principia Mathematica, published in 1687, the English scientist Isaac Newton popularized the notion that matter and even light might be made of tiny, indestructible particles. This idea had a long pedigree, not least because the alternative is continuous matter, which is difficult to understand. Many naturalists wondered whether living things might be made of particles of a different kind; because they believed living things are fundamentally different from nonliving matter, the particles themselves would have to be alive. In 1749, French naturalist Georges-Louis Leclerc, the Comte de Buffon, called them "living molecules." At the same time, biologists were busy familiarizing themselves with the microscopic anatomy, or histology, of plants and animals. Some wrote about their observations of "cellular tissue" and even began to make the connection between their observations and the idea of living molecules. However, many of the "cells" were optical illusions caused by dirty lenses or out-of-focus microscopes — and, in plants at least, the word "cellular" often meant "populated by empty spaces." By the early nineteenth century, however, scientists had begun focusing their ideas — and their microscopes — more acutely. Coming together In the 1820s French botanist Henri Dutrochet boiled plant tissue in nitric acid to dissolve away the material that held the cells together. He watched as the cells separated into countless individual, self-contained "globules," concluding that cells make up "the fruits, the stems, roots, leaves and flowers on all the plants on the surface of the planet." The German botanist Franz Meyen reached a similar conclusion in 1830, observing: "Plant cells occur either singly, so that each forms an individual, as in the case of some algae ... or they are united together to form greater or smaller masses, to constitute a more highly organized plant." Some botanists observed a dark spot inside certain plant cells. In 1831 British botanist Robert Brown gave it a name: the "nucleus." In the 1830s, another German botanist, Matthias Schleiden, suggested that nuclei were the source of new cells after he supposedly saw new cells forming around nuclei and then emerging from inside the cell. In 1837, Schleiden described what he had seen to his colleague, the zoologist Theodor Schwann, who recognized the description of the dark spots as something he had seen in the cells of tadpoles. Schwann was convinced that in animals, too, nuclei seemed to give rise to new cells. Two out of three Schwann thought he also saw nuclei in the spaces between cells. He suggested that all nuclei crystallize from a hypothetical substance which he called "cytoblastema," believing it to be present inside and outside cells. In 1839, he established the first coherent cell theory, based on three principles: first, that every part of every living thing is either made of cells or made by cells; second, that the life of a living organism as a whole is due to the fact that its cells are alive; third, that cells come into existence in or near other cells, from cytoblastema. The last idea was quickly gunned down by biologists who had observed cells dividing in two (binary fission) and realized that they were reproducing. French biologist Barthélemy Dumortier had watched binary fission as early as 1832, even writing that it provided a "perfectly clear explanation of the origin and development of cells," but his observation had remained controversial. Robert Remak, a Polish-German embryologist, carried out painstaking studies of developing embryos in the 1840s and noticed that every new cell arose from the division of preexisting cells. In 1855, German biologist Rudolf Virchow made Remak's observations his own and established and publicized modern cell theory. He dropped Schwann's idea about cytoblastema, replacing it with a Latin phrase: omnis cellula e cellula ("every cell comes from a cell"). This simple idea is crucial to understanding how living things grow and reproduce and, ultimately, for making sense of the process of evolution by which species rise and fall over time. Passing it on Cell theory, combined with improvements in microscopy, made sense of the living world — in particular growth, reproduction and inheritance. Asking ever deeper questions, cell biologists turned to the chemistry of living things: biochemistry. Seeing more clearly Theodor Schwann's idea about cell nuclei crystallizing from cytoblastema is not as absurd as it might seem. The nucleus becomes far less prominent when a cell is about to divide, so it really can seem to appear and disappear. It took two technological advances to show that the nucleus is present all the time and to begin working out its role. The first of these advances was better microscopes. In the 1830s, British physicist Joseph Jackson Lister introduced microscopes with lenses that corrected for spherical aberration (distortion of the image) and chromatic aberration (annoying colored fringes around the image). Ernst Abbe, a German physicist, pushed optical microscope design to its limits in the 1870s, immersing lenses in oil to maximize magnification, resolution, brightness, and contrast. The second important advance was histological staining — the use of dyes that are absorbed only by certain structures in the cell to make those structures stand out. Working with brain cells in 1858 German anatomist Joseph von Gerlach noticed how carmine (cochineal) was taken up by the nucleus and its contents but not by the rest of the cell. The introduction of a range of synthetic dyes in the 1860s opened up the technique, leading to the discovery of several other organelles (see here). Identical twin daughters The nucleus does not disappear during cell division. Instead, it splits into pieces, which are shared out between the two resulting "daughter" cells. In 1882 German biologist Walther Flemming named the material from which the fragments are made chromatin (because it readily absorbed the colored stain he was using). Working with cells from salamanders, Flemming also noticed that during cell division, the chromatin becomes arranged into distinct strands, later named chromosomes; these are pulled apart by tiny, barely visible ropes to form the nuclei of the two daughter cells. The perfectly coordinated dance of tiny colored strands inside a cell nucleus was (and still is) a wonder to behold. He called it mitosis, a term still used today. An easily overlooked point — but one that reveals a profound unity throughout nature — is that soon after Flemming observed mitosis in salamander cells, others soon saw the same dance happening in other animals, plant cells, and fungi (bacterial cells do not have nuclei and reproduce differently, as explored in chapter four). Biologists studying mitosis during cell division noticed that each of the daughter cells ended up not with just a random half of the chromatin material but identical sets of chromosomes. Quite how the cell manages to do that would remain a mystery for decades to come. However, it suggested that the chromosomes carry information essential to the proper functioning of the cell, or perhaps even the whole organism — something like a set of instructions. Sex cells The nature of the information carried by chromosomes became a little clearer in the last few years of the nineteenth century. Biologists noticed that the nuclei of egg and sperm cells (sex cells, or gametes) have half as many chromosomes as cells in ordinary tissue (somatic cells). The process by which the set of chromosomes in a nucleus is reduced by half is another remarkable and intricate chemical dance that came to be called meiosis. During fertilization, the two nuclei fuse together to form a complete, and new, set of chromosomes, different from the chromosome set of either the male or female parent. In that way, both parents contribute equally to the chromosome set of the new individual created by fertilization. It was clear that the chromosomes have something to do with heredity — passing characteristics from generation to generation. They provide instructions for cell housekeeping and a set of instructions on how to build a unique organism, both contained in one tiny part of each tiny cell. In the first few years of the twentieth century, biologists studying heredity rediscovered the work of an Austrian monk, Gregor Mendel. In the 1860s, Mendel had conducted experiments on pea plants, trying to work out the rules of inheritance. He established that each physical trait is carried by factors that come in pairs, one from each parent. Where an individual inherits two different forms of a particular factor, one form is usually dominant. So, for example, if a purebred pea plant with yellow seeds is crossed with a purebred plant with green seeds, the offspring will all have yellow seeds. But cross two plants from that generation, and some will have green seeds, because they have retained the nondominant (or recessive) factor and passed it on to their offspring. Only if an individual plant inherits two copies of the recessive green-seed factor will it have green seeds. Read an Excerpt
The Cell
A Visual Tour of the Building Block of Life
By Jack Challoner, Phil Dash The University of Chicago Press
Copyright © 2015 The Ivy Press Limited
All rights reserved.
ISBN: 978-0-226-22421-3
CHAPTER 1
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Excerpted from The Cell by Jack Challoner, Phil Dash. Copyright © 2015 The Ivy Press Limited. Excerpted by permission of The University of Chicago Press.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
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Table of Contents
INTRODUCTION
Why the cell is Earth’s greatest success story, and the basis of all life.
CHAPTER 1
A Brief History of the Cell
In the 350 years since cells were discovered remarkable progress has been made in our understanding of them.
CHAPTER 2
Inside Living Cells
All types of cell share certain characteristics, including the molecular machinery that makes them work.
CHAPTER 3
Cells Beget Cells
The process of cell division accounts for growth and reproduction, as well as the evolution of new species.
CHAPTER 4
Cellular Singletons
The overwhelming majority of cells on Earth are individual living things— single-celled organisms.
CHAPTER 5
Coming Together— Multicellular Life
Cells cooperate within complex organisms and perform essential specialized tasks.
CHAPTER 6
Life, Death, and Immortality
Cells have evolved extraordinary ways to attack other cells and to protect themselves.
CHAPTER 7
Taking in the Cytes
The human body manufactures around 200 different cell types, displaying astonishing diversity and specialization.
GLOSSARY
INDEX
ACKNOWLEDGMENTS
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