4. The burning issue: molecules and energy

‘The burning issue: molecules and energy’ describes how energy can be transferred through molecular reactions. Metabolic processes are the foundation of cellular life. All chemical reactions increase entropy (or disorder), but living cells maintain their order by carefully controlling metabolic reactions. In living organisms glucose is broken down into pyruvate through glycolysis. Pyruvate then enters the citric acid cycle, which is a series of reactions that generate electrons which generate ATP — the cell's ‘fuel’. Many scientists, most notably Alfred Nobel, have sought to develop molecules which contain huge amounts of energy safely. These molecules can be used to build civilization — or destroy life.

2. Vital signs: the molecules of life

‘Vital signs: the molecules of life’ outlines the molecular basis of life. Understanding molecular life is as much about understanding interactions between molecules and their position within the hierarchical system as it is about identifying the actors. Proteins are a specific type of molecule that perform a huge number of processes inside a biological cell. They are formed by subunits, which in turn are formed from long chains of amino acids. The instructions for these chains are contained, transmitted, and effected using DNA and RNA, another species of long, repeating chains of molecules. The molecular processes and interactions involving these molecules are well understood, but molecular understanding will never give the full story.

3. Take the strain: materials from molecules

‘Take the strain: materials from molecules’ examines the molecular basis of materials science. Nature can perform countless tasks by employing many intricate molecular structures. This hierarchical structure allows the same molecules to display very different properties. In the human body, for example, collagen can be found as a tangle of fibres in the skin, or as a neatly ordered, uniform layer in the cornea. Spiders vary their silk to perform different tasks. Even at a cellular level, tubulin forms cytoskeletal superstructures involved in cell growth and division. Modern synthetic techniques are currently nowhere near nature's complexity, but research into carbon nanotubules may yield exciting results.

7. The chemical computer: molecular information

‘The chemical computer: molecular information’ outlines the ways that molecules can store and transmit information. Genetics is living proof that complex information can be encoded through systems using molecular recognition. Genetic systems have a vast array of copying, proof–reading and editing tools available to them to prevent errors when replicating, transcribing and translating data (although occasional errors — mutations — are essential for evolutionary progress). These tools can be commandeered by scientists to manipulate the genome. Moore's law states that computer power will double every two years. New technologies, such as genetic and molecular computers, are needed to ensure this law holds true.

6. Delivering the message: molecular communication

‘Delivering the message: molecular communication’ explains how molecules can enable communication between cells and in synthetic systems. Hormones are biological messengers which can have short–term or long–term effects. When released into the bloodstream, they travel to the target cells and bind with transmembrane proteins, initiating a signal transduction relay inside the cell. Neurons cells carry electrical action potentials along the nervous system. At neuronal synapses, chemical neurotransmitters carry signals across the synaptic cleft and transfer them to the next neuron along. Supramolecular chemists aim to utilise or mimic signal transduction pathways in a range of applications, from pharmaceuticals to mechanical olfaction.

5. Good little movers: molecular motors

‘Good little movers: molecular motors’ examines molecular motors in cells, before looking at the field of nanotechnology. There are many types of movement in the human body powered by motor proteins. Dynein and kinesin are used to beat respiratory cilia and move items around cells. More visibly, the sliding filament theory explains how actin, myosin, and tropomyosin control muscle contraction. The smallest mechanical motors currently made by humans dwarf these systems. Nanotechnology may provide a means to control motion at the molecular level and enable precise chemical synthesis, but it may be easier to use existing protein motors than to construct them from scratch.

1. Engineers of the invisible: making molecules

‘Engineers of the invisible: making molecules’ explores how molecules can be explained, represented, and manufactured. Chemistry studies the properties of elements, and molecules are the smallest units of ‘meaning’ in this field. One analogy likens them to ‘words’ made from atomic ‘letters’. Molecules are impossible to ‘see’ in the spectrum of visible light, but many methods exist to visualize them. Some methods are experimental, like X-ray crystallography; others are theoretical, using quantum theory to predict structures. Scientists can synthesize molecules in a laboratory. This is now a relatively advanced science, but the complexity of nature's creation still dwarfs humanity's achievements.