Cell Biology

The cell is the structural and functional unit of all living organisms, sometimes called the “building blocks of life”. Knowing the composition of cells and how cells works is fundamental to all of the biological sciences. Cells are composed of water, inorganic ions, and carbon-containing (organic) molecules. Water is the most abundant molecule in cells, accounting for 70% or more of total cell mass. Consequently, the interactions between water and the other constituents of cells are of central importance in biological chemistry. The critical property of water in this respect is that it is a polar molecule, in which the hydrogen atoms have a slight positive charge and the oxygen has a slight negative charge. Because of their polar nature, water molecules can form hydrogen bonds with each other or with other polar molecules, as well as interacting with positively or negatively charged ions. Cell surface receptors (membrane receptors, transmembrane receptors) are specialized integral membrane proteins that take part in communication between the cell and the outside world. Extracellular signalling molecules (usually hormones, neurotransmitters, cytokines, growth factors or cell recognition molecules) attach to the receptor, triggering changes in the function of the cell. This process is called signal transduction: The binding initiates a chemical change on the intracellular side of the membrane. In this way the receptors play a unique and important role in cellular communications and signal transduction. This book on molecular biology of the cell concerned mainly with those properties that are common to biological cells. It also discusses issues such as internal organization of the cell, nature and functions of cell components and molecular genetics.