Introduction to the Human Cell. Danton PhD O'Day

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      Copyright 2012 Danton O'Day,

      All rights reserved.

      Published in eBook format by eBookIt.com

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      ISBN-13: 978-1-4566-0970-2

      No part of this book may be reproduced in any form or by any electronic or mechanical means including information storage and retrieval systems, without permission in writing from the author. The only exception is by a reviewer, who may quote short excerpts in a review.

      Preface

      In this book, we look at the fundamental biology of the human cell from the outside in. While genes and mutations define our cells and how they function, this volume focuses on the biology of the cell rather than on the nuts and bolts of molecular biology. As a result, the book focuses primarily on protein function in normal and diseased states. The volume reveals how cells are constructed and how they are organized so they work effectively. In each case this understanding is related back to what is known about how mutations and foreign agents lead to many common diseases and ailments. The goal is to develop a holistic view of the normal human cell to set the stage for an understanding of its primary importance in disease and human existence. More to the point, with the development of exciting new technologies, cells are the new frontier in the fight against disease. This book will set the stage for understanding why this is true. This book is written in an easy to read style with lots of relevant examples. It is designed to meet the needs of students world-wide who want an accurate, informative and inexpensive book on the structure and function of the human cell. The book is suitable for use as a course textbook or as supplementary reading to help students understand how cells function. Anyone who has taken a biology course will also find this book an enjoyable read, allowing them to update their understanding of current biomedical issues that make the news.

      About the Author

      Danton H. O’Day, PhD, is Professor Emeritus in Biology on the University of Toronto Mississauga Campus and in the Department of Cell & Systems Biology at the University of Toronto. He has lectured and done research on Cell Biology for over 40 years. To date he has over 120 referred publications in the field as well as several edited books and multiple book chapters. He has taught and lectured in Canada, the USA, the UK, in many European countries and in Africa. This book reflects his view of the cell and his desire to teach everyone about cells and how they function.

      Acknowledgements

      I’m indebted to Robert Huber, Andrew Catalano and Aldona Budniak for their editorial comments on the content of this book. Andrew contributed some of the content to Chapter 20 which is greatly appreciated. I also thank Aldona for some of the graphics on receptor mediated endocytosis and for her editorial insights. Nima Vaezzadeh kindly supplied a few cell junction figures. Robert Huber and Yekaterina Poloz contributed figures for the Appendices.

      Introduction to

      The Human Cell

      The Unit of Life & Disease

      Danton H. O’Day, PhD

      Chapter 1

      Introduction

      In this book, we’ll cover a diversity of human diseases to increase our understanding of the human cell. Cancer will be examined from a variety of standpoints with foci on cell adhesion and communication as well as cell movement and chemotaxis. Diseases such as Tay-Sachs disease will enlighten us to the critical role of enzymes that at one time were considered to function only during digestion but are now known to be central to cellular and human survival. An analysis of hypercholesterolemia will reveal how molecules selectively enter cells and are subsequently processed through a series of steps that involve carefully regulated movements and fusions of vesicles. Other chapters will look at the cellular basis of bacterial and viral infections and how they use mimicry to infect human cells. These are but a few examples of the novel approach that is taken to understand the role of human cell biology in normal and diseased states.

      The Unit of Life and Disease

      It has often been said that the cell is the “unit of life.” In other words, anything less than a cell is not considered to be a living creature. The cell is the sole unit that possesses all the criteria that define life. It is able to survive, grow and reproduce on its own. A virus is not considered to be living because it cannot reproduce on its own—it needs to use the machinery present in a living cell to reproduce. The cell is also the “unit of disease” because all human diseases operate at the cellular level. Thus a virus can’t get a disease but it can cause a disease by infecting cells. Unlike viruses, bacteria are cells. Bacteria can also cause human diseases—they do so by infecting cells. Again, this reflects the cell as the basis of disease. This is true for human cells just as it is for the cells of all living creatures. In this book we will look at how the human cell is constructed and, by focusing on specific components and events, understand how it functions. By focusing on a select group of diseases that affect the diverse components and functions of cells further insight will be gained into the normal and abnormal functioning of the human cell.

      The survival and normal function of every cell requires an ongoing, dynamic interaction between all of its internal components. When these processes go wrong or when agents interfere with them, then problems arise. The internal functions of cells must also work in concert with events occurring both at the cell surface and outside the cell in the extracellular environment. The goal of this book is to introduce the reader to these interactions to set the stage for an understanding of the complexity of cellular structure and function. Several diseases will be discussed to show how the cell serves as the “unit of disease.” We will do this by first dismantling the cell and discussing many of its constituents. After discussing how they function and how they interact with other components, we will begin to show how the cell is more than the sum of its parts. In each case we will show how disrupting cell function through genetic mutation, chemical intervention or infectious agents can lead to various diseases.

      The Cell Inside-Out

      We will begin with basic cell structure and cellular compartmentalization to set the stage for subsequent chapters. As shown in Figure 1.1, each and every human cell is surrounded by a cell membrane. It is an organized structure comprised of lipids, proteins and carbohydrates. The cell membrane is the interface between the cell and its environment. If the cell membrane is disrupted the cell will die. The membrane still must remain flexible and able to respond appropriately to external conditions. Human cells do not have cell walls. Plants, microbes, fungi and bacteria have cell walls that exist outside of their cell membranes serving as support and protection.