Cell Biology

A Short Course

Stephen R. Bolsover, Andrea Townsend-Nicholson, Greg FitzHarris, Elizabeth A. Shephard, Jeremy S. Hyams, Sandip Patel

• Publisher: Wiley-Blackwell
• Year: 2022
• ISBN:
  9781119757788
• Edition: 4
• Topic: Biological Sciences
• Subtopic: Cell Biology
• Index: Biological Sciences

An accessible and straightforward intro to cell biology

In the newly revised Fourth Edition of Cell Biology: A Short Course, a distinguished team of researchers delivers a concise and accessible introduction to modern cell biology, integrating knowledge from genetics, molecular biology, biochemistry, physiology, and microscopy. The book places a strong emphasis on drawing connections between basic science and medicine.

Telling the story of cells as the units of life in a colorful and student-friendly manner, Cell Biology: A Short Course takes an "essentials only" approach. It conveys critical points without overburdening the reader with extraneous or secondary information. Clear diagrams and examples from current research accompany special boxed sections that focus on the importance of cell biology in medicine and industry. A new feature, "BrainBoxes" describes some of the key people who created the current understanding of Cell Biology.

The book has been thoroughly revised and updated since the last edition and includes:

• Thorough introduction to cells and tissues, membranes, organelles, and the structure of DNA and genetic code
• Explorations of DNA as a data storage medium, transcription and the control of gene expression, and recombinant DNA and genetic engineering
• Discussion of the manufacture of proteins, protein structure, and intracellular protein trafficking
• Description of ions and voltages, intracellular and extracellular signaling
• Introduction to the cytoskeleton and cell movement
• Discussion of cell division and apoptosis

Perfect for undergraduate students seeking an accessible, one-stop reference on cell biology, Cell Biology: A Short Course is also an ideal reference for pre-med students.

SECTION 1
THE STRUCTURE OF THE CELL

The cell is the fundamental unit of life. A cell comprises a complex and ordered mass of protein, nucleic acid, and many biochemical species separated from the world outside by a limiting membrane. Cells expend energy to maintain a highly ordered state, and this expenditure of energy and the ability to repair themselves distinguishes living cells from lifeless packets of biological material such as viruses. In the first two chapters we will describe the basic structure of cells and how they can be observed with a microscope. We will describe how, in animals, cells containing the same DNA database assume very different shapes and functions and organize themselves into tissues.

• Chapter 1: A Look at Cells and Tissues
• Chapter 2: Membranes and Organelles

1
A LOOK AT CELLS AND TISSUES

With very few exceptions, all living things are either a single cell or an assembly of cells. This chapter will begin to describe what a cell is, and further chapters will say much more. However, to begin with, we can briefly describe a cell as an aqueous (watery) droplet enclosed by a lipid (fatty) membrane. Cells are, with a few notable exceptions, small (Figure 1.1), with dimensions measured in micrometers (μm, 1 μm = 1/1000 mm). They are more or less self‐sufficient: a single cell taken from a human being can survive for many days in a dish of nutrient broth, and many human cells can grow and divide in such an environment. In 1838 the botanist Matthias Schleiden and the zoologist Theodor Schwann formally proposed that all living organisms are composed of cells. Their “cell theory,” which nowadays seems so obvious, was a milestone in the development of modern biology. Nevertheless, general acceptance took many years, in large part because the plasma membrane (Figure 1.2), the membrane surrounding the cell that divides the living inside from the nonliving extracellular medium, is too thin to be seen using a light microscope. Microorganisms such as bacteria, yeast, and protozoa exist as single cells. In contrast, the adult human is made up of about 30 trillion cells (1 trillion = 10¹²), which are mostly organized into collectives called tissues.

ONLY TWO TYPES OF CELL

Superficially at least, cells exhibit a staggering diversity. Some have defined, geometric shapes; others have flexible boundaries; some lead a solitary existence; others live in communities; some swim, some crawl, and some are sedentary. Given these differences, it is perhaps surprising that there are only two types of cell (Figure 1.2). Prokaryotic (Greek for “before nucleus”) cells have very little visible internal organization so that, for instance, the genetic material, stored in the molecule deoxyribonucleic acid (DNA), is free within the cell. These cells are especially small, the vast majority being 1–2 μm in length. The prokaryotes are made up of two broad groups of organisms, the bacteria and the archaea (Figure 1.3). The archaea were originally thought to be an unusual group of bacteria but we now know that they are a distinct group of prokaryotes with an independent evolutionary history. The cells of all other organisms, from yeasts to plants to worms to humans, are eukaryotic (Greek for “with a nucleus”). These are generally larger (5–100 μm, although some eukaryotic cells are large enough to be seen with the naked eye; Figure 1.1) and structurally more complex. Eukaryotic cells contain a variety of specialized structures known collectively as organelles, embedded within a viscous substance called cytosol. Their DNA is held within the largest organelle, the nucleus. The structure and function of organelles will be described in detail in subsequent chapters. Table 1.1 summarizes the differences between prokaryotic and eukaryotic cells.

Figure 1.1. Dimensions of some example cells. 1 mm = 10⁻³ m; 1 μm = 10⁻⁶ m; 1 nm = 10⁻⁹ m.

Cell Division

One of the major distinctions between prokaryotic and eukaryotic cells is their mode of division. In prokaryotes the circular chromosome is duplicated from a single replication origin by a group of proteins that reside on the inside of the plasma membrane. At the completion of replication the old and new copies of the chromosome lie side by side on the plasma membrane which then pinches inwards between them. This process, which generates two equal, or roughly equal, daughter cells is described as binary fission. In eukaryotes the large, linear chromosomes, housed in the nucleus, are duplicated from multiple origins of replication by enzymes located in the nucleus. Sometime later the nuclear envelope breaks down and the replicated chromosomes are compacted so that they can be segregated without damage during mitosis. We will deal with mitosis in detail in Chapter 14. For the moment we should be aware that although it is primarily about changes to the nucleus, mitosis is accompanied by dramatic changes in the organization of the rest of the cell. A new structure, the mitotic spindle, is assembled specifically to move the chromosomes apart whilst other str...