2.0: Introduction

In which we consider what biology is all about, namely the study of life, that is organisms and how they work. We discover that organisms are built of one or more, to millions to billions of cells. Social processes are involved in multicellular organisms and when single-celled organisms act in a coordinated manner. We consider plausible models for the origins of organisms and their relationships to one another.

Biology is the science of organisms, how they function, behave, interact, and vary genetically from one another. How individual organisms adapt and how populations of organisms evolve over time. Organisms are discrete, highly organized, bounded but open, non-equilibrium physicochemical systems. That is a lot of words! what do they all mean? How is a mushroom that looks like a rock different from a rock? What is genetic variation and how does it influence the properties and behaviors of an organism? How, exactly, is one mushroom different from another? What exactly is a bounded, non-equilibrium system? The answers are not simple; they assume a working knowledge of core principles from physics and chemistry and experimental observations. For example, to understand what it means to be a “bounded, non-equilibrium system” you need to understand basic thermodynamics (which we consider in Chapter 5). Non-equilibrium systems can do various forms of work, and work is an outcome or behavior that requires energy to achieve. Work includes generating movement and molecular gradients, and driving a range of unfavorable reactions that include the synthesis of nucleic acids, proteins, lipids, carbohydrates, and other types of molecules.

We will focus on what is known as Gibbs free energy; the energy available to do work. The free energy of a system at equilibrium is zero. Organisms maintain their non-equilibrium state by importing free energy in the form of light and chemically unstable molecules from the external world. Organisms contain information that can be replicated, changed, and passed from parent to offspring. Other types of non-equilibrium systems, such as hurricanes and tornados, occur – they differ from organisms in that they are transient and arise de novo, that is, they do not have “parents”. When they disappear they leave no offspring, no baby hurricanes or tornados. In contrast, each organism alive today arose from one or more pre-existing organisms, its parent(s) and that each and every organism, past, present, and future has an uninterrupted history stretching back billions of years. A remarkable conclusion, given the fragility of life.

Biology is based on a few over arching theories. The Cell Theory explains the historic continuity of organisms, while Evolution Theory explains the observed fossil record, the diversity of organisms, how populations of organisms change over time, and extinction. The Physicochemical Theory of Life explains the remarkable properties of (and behaviors) of organisms without violating the laws that govern all physical and chemical systems.^[44]

---