BIOGRAPHY
Karen Vipond is a lecturer at the School of Healthcare Sciences at Bangor University, UK. She has combined her different careers as a biologist and a nurse in order to teach biological sciences to health care professionals. Karen’s career experiences have been quite varied as she has worked as a biologist, a teacher, a trauma nurse, a district nurse, a health visitor and a medical research co-ordinator for Oxford University and the World Health Organization. Karen was a student at St Anne’s College at the University of Oxford as well as Oxford Brookes University and she trained as a nurse at the John Radcliffe Hospital, Oxford. During her clinical career she worked in Oxfordshire, Buckinghamshire and in North Wales.
ACKNOWLEDGEMENTS
I would like to thank the following individuals for their help in the production of this book:The staff and students at the School of Healthcare Sciences at Bangor University for acting as ‘models’ for the photographs in Chapter 2; Ifor Williams, IT Technician at Bangor University for taking the photographs in Chapter 2; Marion Poulton, Librarian at the School of Healthcare Sciences for her help with proofreading the work; Carolyn Owen, Genetic Counsellor at Ysbyty Gwynedd, Bangor, for being a critical reader for Chapter 10; Joshua Vipond for his work in checking the scientific explanations of inheritance throughout the book; Judith Harvey for all her help and advice during the whole process of writing the book.
Copyright material
I would also like to thank the National Library of Medicine – National Institutes of Health, Bethesda, Maryland, USA, for their permission to reproduce illustrations in this book.
Most of the illustrations in this book have either been sourced from the National Library of Medicine or are the Author’s own. However, if any copyright material has been used inadvertently without permission or acknowledgement I, as the Author, apologise and will make any necessary correction(s) at the first opportunity.
Dedication
To Joshua and Libby who have inherited half my genes, and to Phil who also contributed half his genes. Also to the rest of my family with whom I share the same genetic material.
| LEARNING OUTCOMES |
The following topics are covered in this chapter:
• Cellular structure and function;
• Chromosomes;
• The cell cycle;
• Deoxyribonucleic acid (DNA);
• Protein synthesis;
• Mitochondrial DNA.
INTRODUCTION
The activities that occur within cells give us an understanding of how human traits are inherited. Knowledge of cellular function gives rise to the understanding of how the body works. The human body is made up of trillions of cells, many of which have specialised functions. Despite this, all cells share certain features:
• cells arise from the division of pre-existing cells;
• cells interact, they send and receive information;
• cells produce proteins for growth repair and normal body functioning;
• cells contain all the genetic instructions for the body.
All cells in the body behave in this way apart from red blood cells. Red blood cells are not considered to be true cells by the time they reach the blood stream as they do not contain a nucleus. Cells are the basic building blocks of all living matter.
CELL STRUCTURE
Cells have many parts, each with a specialised function. Any structure within the cell that has a characteristic shape and function is termed an organelle. Most organelles are too small to be seen through a light microscope but can be seen with an electron microscope (see Figure 1.1).
Figure 1.1 Cell structure
Plasma membrane
This is the outer lining of the cell. It is composed of a bilipid layer through which certain molecules can enter the cell (endocytosis) and wastes can exit (exocytosis).
Figure 1.2 The outer lining of the cell
Nucleus
The nucleus functions as the control centre of the cell (Figure 1.3). It contains DNA (Deoxyribonucleic Acid) which is the cell’s genetic material. A double membrane separates the contents of the nucleus from the rest of the cell.This nuclear membrane (also called the nuclear envelope) is perforated by nuclear pores.
Figure 1.3 Nucleus
Nucleolus
The nucleolus (Figure 1.4) is a morphologically distinct area within the nucleus which is involved in the production of Ribonucleic Acid (RNA).
Figure 1.4 Nucleolus
Cytoplasm
Cytoplasm is a gel-like fluid that contains all the organelles and the enzymatic systems which provide energy for the cell.
Cytoskeleton
The cytoskeleton is a network of fibres made from the protein tubulin (Figure 1.5). This provides the structural framework of the cell and functions in cellular shape, cell division and cell motility, as well as directing movement of the organelles within the cell.
Figure 1.5 Cytoskeleton
Endoplasmic reticulum
The endoplasmic reticulum is an organelle that processes the molecules made by the cell (Figure 1.6). The endoplasmic reticulum transports these molecules to their specific destinations.
Figure 1.6 Endoplasmic reticulum
Ribosomes
