Acknowledgements xv About the CompanionWebsite xvii 1 Astrobiology and Life 1 1.1 About this Textbook 1 1.2 Astrobiology and Life 4 1.3 What is Astrobiology? 4 1.4 History of Astrobiology 6 1.5 What is Life? 9 1.6 Conclusions 12 Further Reading 12 2 Matter, the Stuff of Life 13 2.1 Matter and Life 13 2.
2 We are Made of ''Ordinary'' Matter 13 2.3 Matter: Its Nucleus 14 2.3.1 Isotopes 14 2.4 Electrons, Atoms and Ions 15 2.5 Types of Bonding in Matter 15 2.6 Ionic Bonding 15 2.6.
1 Ionic Bonds and Life 16 2.7 Covalent Bonding 17 2.7.1 Covalent Bonds and Life 17 2.8 Metallic Bonding 19 2.9 van der Waals'' Interactions 19 2.9.1 Dipole-dipole (Keesom) Forces 19 2.
9.2 Dipole-induced Dipole (Debye; Pronounced deh-beye) Forces 19 2.9.3 Dispersion Forces 20 2.9.4 van der Waals'' Interactions and Life 20 2.10 Hydrogen Bonding 20 2.10.
1 Hydrogen Bonds and Life 21 2.11 The Equation of State Describes the Relationship between Different Types of Matter 21 2.12 Phase Diagrams 22 2.12.1 Matter and Mars 23 2.12.2 Phase Diagrams and Life 24 2.13 Other States of Matter 25 2.
13.1 Plasma 25 2.13.2 Degenerate Matter 25 2.14 The Interaction between Matter and Light 27 2.14.1 The Special Case of the Hydrogen Atom 29 2.14.
2 Uses to Astrobiology 29 2.15 Conclusions 30 Further Reading 30 3 Life''s Structure: Building the Molecules 33 3.1 Building Life 33 3.2 The Essential Elements: CHNOPS 33 3.3 Carbon is Versatile 34 3.4 The Chains of Life 35 3.5 Proteins 35 3.6 Chirality 37 3.
7 Carbohydrates (Sugars) 38 3.8 Lipids 39 3.9 The Nucleic Acids 39 3.9.1 Ribonucleic Acid 40 3.10 The Solvent of Life 43 3.10.1 Water as the Best Solvent 43 3.
11 Alternative Chemistries 44 3.11.1 Alternative Core Elements 44 3.11.2 Alternative Solvents 47 3.12 The Structure of Life and Habitability 48 3.13 Conclusion 49 Further Reading 49 4 Life''s Structure: Building Cells from Molecules 51 4.1 From Molecules to Cells 51 4.
2 Types of Cells 51 4.3 Shapes of Cells 53 4.4 The Structure of Cells 53 4.5 Membranes 55 4.5.1 Gram-negative and Positive Prokaryotic Membranes 56 4.5.2 Archeal Membranes 58 4.
6 The Information Storage System of Life 58 4.6.1 Transcription - DNA to RNA 59 4.6.2 Translation - RNA to Protein 60 4.6.3 A Remarkable Code 62 4.6.
4 DNA Replication 62 4.6.5 Plasmids 64 4.6.6 eDNA 65 4.7 Cell Reproduction 65 4.8 The Growth of Life 67 4.9 Moving and Communicating 68 4.
9.1 Movement in Prokaryotes 68 4.9.2 Communication in Prokaryotes 68 4.10 Eukaryotic Cells 70 4.10.1 Endosymbiosis 72 4.11 Viruses 72 4.
12 Prions 74 4.13 Conclusions 74 Further Reading 74 5 EnergyforLife 77 5.1 Energy and Astrobiology 77 5.2 Life and Energy 78 5.3 The Central Role of Adenosine Triphosphate 78 5.4 Chemiosmosis and Energy Acquisition 80 5.5 What Types of Electron Donors and Acceptors can be Used? 83 5.6 Aerobic Respiration 83 5.
7 Anaerobic Respiration 86 5.8 Fermentation 88 5.9 Chemoautotrophs 88 5.9.1 Methanogens and Methanotrophs 90 5.9.2 Sulfur Cycling 91 5.9.
3 Iron Oxidisers 91 5.9.4 Nitrogen Cycling and the Chemoautotrophs 91 5.10 Energy from Light: Oxygenic Photosynthesis 92 5.11 Anoxygenic Photosynthesis 94 5.12 Global Biogeochemical Cycles 97 5.13 Microbial Mats - Energy-driven Zonation in Life 99 5.14 The Thermodynamics of Energy and Life 100 5.
14.1 Gibbs Free Energy: The Energy in Reactants and Products 100 5.14.2 Gibbs Free Energy: The Concentration of Compounds 100 5.14.3 Gibbs Free Energy: Using Redox Reactions 100 5.15 Life in Extremes 103 5.16 Conclusions 103 Further Reading 103 6 TheTreeofLife 105 6.
1 A Vast Diversity of Life 105 6.2 The Tree of Life 106 6.3 Some Definitions 106 6.4 Classifying Organisms 106 6.5 Homology and Analogy 109 6.6 Building a Phylogenetic Tree 110 6.7 Some Definitions and Phylogenetic Trees 112 6.8 Types of Phylogenetic Trees 113 6.
9 Using Phylogenetic Trees to Test Hypotheses 113 6.10 Complications in Building the Universal Tree of Life 115 6.10.1 Endosymbiosis 116 6.10.2 Horizontal Gene Transfer 117 6.11 The Last Universal Common Ancestor 119 6.12 Molecular Clocks 120 6.
13 Alien Life 121 6.14 Conclusions 121 Further Reading 121 7 The Limits of the Biospace 123 7.1 The Biospace 123 7.2 The Importance of the Biospace for Astrobiology 123 7.3 The Edges of the Biospace are Dominated by Microbes 124 7.4 Life at High Temperatures 126 7.4.1 Uses for Thermostable Molecules 127 7.
5 Life at Low Temperatures 127 7.6 Salt-loving Organisms 129 7.6.1 Salt-in Strategy 130 7.6.2 Salt-out Strategy 130 7.6.3 Low Water Activity 130 7.
7 pH Extremes 130 7.8 Life Under High Pressure 132 7.9 Tolerance to High Radiation 132 7.10 Life in Toxic Brews 134 7.11 Life on the Rocks 134 7.12 Polyextremophiles - dealing with Multiple Extremes 136 7.13 Life Underground 137 7.14 Dormancy in Extreme Conditions 138 7.
15 Eukaryotic Extremophiles 139 7.16 Are there Other Biospaces? 140 7.17 The Limits of Life: Habitability Revisited 140 7.18 Conclusions 140 Further Reading 141 8 The Formation of the Elements of Life 143 8.1 In the Beginning 143 8.2 Low Mass Stars 147 8.3 High Mass Stars 149 8.4 The Elements of Life 150 8.
5 The Hertzsprung-Russell Diagram 152 8.6 The Sun is a Blackbody 156 8.7 The Formation of Planets 157 8.8 Types of Objects in our Solar System 159 8.9 Laws Governing the Motion of Planetary Bodies 160 8.10 Meteorites 163 8.11 Conclusions 165 Further Reading 165 9 Astrochemistry - Carbon in Space 167 9.1 Astrochemistry: The Molecules of Life? 167 9.
2 Observing Organics 167 9.3 In the Beginning 168 9.4 Different Environments 169 9.4.1 Diffuse Interstellar Clouds 169 9.4.2 Molecular Clouds 169 9.4.
3 Protoplanetary Disc 170 9.4.4 Carbon-rich Stars 171 9.4.5 Shock Waves from Supernova Explosions and Other Astrophysical Violence 172 9.5 How are Compounds Formed? 172 9.6 Interstellar Grains 174 9.7 Forming Carbon Compounds 175 9.
8 Polycyclic Aromatic Hydrocarbons 176 9.9 Even More Carbon Diversity 176 9.9.1 Prebiotic Compounds 177 9.10 Comets 178 9.11 Chirality 179 9.12 Laboratory Experiments 179 9.13 Observing these Molecules 180 9.
14 Conclusions 181 Further Reading 182 10 The Early Earth (The First Billion Years) 183 10.1 The First Billion Years of the Earth 183 10.2 The Earth Forms and Differentiates 183 10.3 The Formation of the Moon 184 10.4 The Early Oceans 186 10.5 The Early Crust 187 10.6 The Early Atmosphere 188 10.7 The Temperature of the Early Earth 189 10.
8 The Late Heavy Bombardment 189 10.9 Implications of the Early Environment for Life 192 10.10 Conclusion 194 Further Reading 194 11 The Origin of Life 197 11.1 Early Thoughts on the Origin of Life: Spontaneous Generation 197 11.2 Some Possible Ideas for the Origin of Life 200 11.3 The Synthesis of Organic Compounds on the Earth 200 11.3.1 Possible Reaction Pathways 202 11.
4 Delivery from the Extraterrestrial Environment 204 11.5 The RNA World 206 11.6 Early Cells 208 11.7 Where did it Happen? 210 11.7.1 Deep Sea Hydrothermal Vents 210 11.7.2 Land-based Volcanic Pools 211 11.
7.3 Impact Craters 211 11.7.4 Beaches 212 11.7.5 Bubbles 213 11.7.6 The Deep Sub-Surface 213 11.
7.7 Mineral Surfaces 213 11.8 A Cold Origin of Life? 214 11.9 The Whole Earth as a Reactor? 214 11.10 Conclusions 214 Further Reading 214 12 Early Life on Earth 217 12.1 Early Life on the Earth 217 12.2 Early Life - Metabolisms and Possibilities 217 12.3 Isotopic Fractionation 220 12.
3.1 Carbon Isotopes 221 12.4 Measuring the Isotope Fraction: The Delta Notation 221 12.5 Sulfur Isotope Fractionation 223 12.6 Using Ancient Isotopes to Look for Life 223 12.7 Morphological Evidence for Life 225 12.7.1 How are Microorganisms Fossilised? 225 12.
7.2 Evidence for Fossil Microbial Life 225 12.7.3 Stromatolites 229 12.8 Biomarkers 230 12.9 The Search for Extraterrestrial Life 230 12.10 Conclusions 231 Further Reading 231 13 The History of the Earth 233 13.1 The Geological History of the Earth 233 13.
2 Minerals and Glasses 233 13.3 Types of Rocks 235 13.3.1 Igneous Rocks 235 13.3.2 Sedimentary Rocks 235 13.3.3 Metamorphic Rocks 236 13.
4 The Rock Cycle 237 13.5 The Composition of the Earth 239 13.6 The Earth''s Crust and Upper Mantle 239 13.7 Plate Tectonics 240 13.8 Dating Rocks 244 13.9 Age-dating Rocks 246 13.9.1 Absolute Dating of Rocks 246.