Microbial Evolution and Early Life on Earth

Earth's formation = 4.5 BYA Absence of liquid water on Earth = Before 4.5 BYA Start of the great oxidation event = 2.5 BYA Oldest known mineral (Jack Hills Zircon) formed = Hadean eon

Anoxic = Condition of Earth when there was no ozone layer Volcanic outgassing = Process that originated water on Earth Liquid bilayers = Replaced mineral pores, forming the first true cells Zircons = Default standard for rock dating, resistant to chemical changes

Earth's oldest surviving sedimentary rocks (formed underwater) = 3.86 billion years old Ancient zircon crystals = Provide evidence for a solid crust and liquid water as early as 4.3 BYA Deep sea hydrothermal vents = Likely a site for the origin of life on Earth Submarine mounds = Possible link to the origin of life

<p>Origin of life on Earth = Before 4.3 BYA Earth's anoxic condition = 2.5 BYA Rise of oxidation = During the start of the oxidation event Origin of water on Earth = From the innumerable collisions with icy comets and asteroids</p> Signup and view all the answers

<p>Slowly decaying radioactive isotopes = Used to determine the age of Earth Unusual chemical traces in rocks = May suggest that life existed when they formed Mineral pores = Form the first biological compartments in the subsurface hypothesis Hydrothermal vents = Contain present nutrients and are likely a site for the origin of life</p> Signup and view all the answers

<p>Formation of the first true cells = After the first biological compartments were formed Presence of water on early Earth = In the form of water vapor due to Earth's high temperatures Start of the great oxidation event = After Earth became anoxic Formation of the Jack Hills Zircon = During the Hadean eon</p> Signup and view all the answers

<p>Liquid water = A requirement for life Hadean eon = Period when the Jack Hills Zircon, the oldest known mineral, formed Rock dating = Done using zircons as they are resistant to chemical changes Subsurface Hypothesis = Theory that life originated in the ocean floor</p> Signup and view all the answers

<p>Jack Hills Zircon = Oldest known mineral formed in the Hadean eon Earth's oldest surviving sedimentary rocks = 3.86 billion years old Ancient zircon crystals = Provide evidence for a solid crust and liquid water as early as 4.3 BYA Volcanic outgassing = Process that originated water on Earth</p> Signup and view all the answers

<p>Absence of liquid water on early Earth = Due to intense heat and no ozone layer Earth's anoxic condition = 2.5 BYA, before the start of the great oxidation event Origin of water on Earth = From the innumerable collisions with icy comets and asteroids Zircons = Resistant to chemical changes and used as default standard for rock dating</p> Signup and view all the answers

<p>Origin of life on Earth = Before the start of the great oxidation event Earth's formation = About 4.5 BYA Rise of oxidation = During the start of the oxidation event Formation of the first true cells = After the first biological compartments were formed</p> Signup and view all the answers

<p>Surface Hypothesis = Not possible due to the Earth's hot surface Gene-First/ RNA World Hypothesis = Life began with the emergence of RNA molecules that could self-replicate and catalyze other reactions Metabolism-First Hypothesis = The formation of cells came first, followed by enzymes, and finally genes Great Oxidation Event = Happened around 2.4 BYA and involved the production of oxygen by cyanobacteria</p> Signup and view all the answers

<p>Anaerobes = Organisms that can live without oxygen Thermophilic chemolithotrophs = Organisms that grow at high temperatures and obtain energy from inorganic compounds Hyperthermophiles = Organisms that grow at extremely high temperatures, between 80C and 113C Archaeoglobus and Pyrococcus = Organisms found in deep subterranean fluids under the North Sea</p> Signup and view all the answers

<p>RNA = Self-replicated and catalyzed other reactions in the Gene-First/ RNA World Hypothesis Proteins = Became the main catalytic molecules after the evolution of RNA enzymes DNA = Evolution of DNA and RNA polymerase led to the conversion from RNA to DNA based genomes Lipid bilayer = The site of electron transport and likely important for energy conservation</p> Signup and view all the answers

<p>LUCA = Likely existed at 3.7-3.8 BYA, the point at which Bacteria and Archaea diverged Archaea = One of the three domains of life, along with Bacteria and Eukarya Cyanobacteria = Produced oxygen through photosynthesis, leading to 'The Great Oxidation Event' Bacteria = One of the three domains of life, along with Archaea and Eukarya</p> Signup and view all the answers

<p>Oxygenic Photosynthesis = 6CO2 + 12H2O + light energy -&gt; C6H12O6 + 6O2 + 6H2O Anoxygenic Photosynthesis = CO2 + 2H2A + light energy -&gt; [CH2O] + 2A + H2O Generation of Ozone = Absorbs UV light and forms a protective layer in the atmosphere Iron Oxidation by Cyanobacteria = The metabolism of cyanobacteria yielded O2 that oxidized reduced minerals containing Fe2+ to iron oxidizes containing Fe3+</p> Signup and view all the answers

<p>LUCA = Last Universal Common Ancestor, a cellular organism that had a lipid bilayer and used DNA, RNA, and protein Hyperthermophiles = Organisms that grow at extremely high temperatures, between 80C and 113C Metabolism-First Hypothesis = Hypothesis that suggests the formation of cells came first, followed by enzymes, and finally genes Surface Hypothesis = Hypothesis that was not possible because the surface of the Earth was too hot for life</p> Signup and view all the answers

<p>The Great Oxidation Event = Happened around 2.4 BYA and involved the production of oxygen by cyanobacteria 3.7-3.8 BYA = The point at which Bacteria and Archaea diverged, likely when LUCA existed 2.4 BYA = The time when the Great Oxidation Event occurred 80C – 113C = The temperature range at which hyperthermophiles grow</p> Signup and view all the answers

<p>RNA World = Hypothesis that suggests life began with the emergence of RNA molecules that could self-replicate and catalyze other reactions Anaerobes = Organisms that can live without oxygen, likely the type of organism LUCA was Lipid Bilayer = Structure that likely played a key role in early life by containing and protecting biomolecules Metabolism-First Hypothesis = Hypothesis that suggests the formation of cells came first, followed by enzymes, and finally genes</p> Signup and view all the answers

<p>Oxygenic Photosynthesis = Produces glucose and oxygen Anoxygenic Photosynthesis = Produces a reduced carbon compound and an oxidized electron donor Iron Oxidation by Cyanobacteria = Produces iron oxidizes containing Fe3+ Generation of Ozone = Produces a protective layer in the atmosphere</p> Signup and view all the answers

<p>Archaea = One of the three domains of life, often found in extreme environments Bacteria = One of the three domains of life, often found in diverse habitats LUCA = The last universal common ancestor, likely an anaerobic organism Cyanobacteria = Organisms that played a key role in the Great Oxidation Event by producing oxygen</p> Signup and view all the answers

<p>Endosymbiotic Theory = The organelles of eukaryotic cells arose from prokaryotic cells that had developed a symbiotic relationship with the eukaryote-to-be Serial endosymbiosis hypothesis = Eukaryotic ancestor diverged from archaeal line and possessed a nucleus prior to endosymbiosis with bacterial ancestor of the mitochondrion Symbiogenesis hypothesis = Eukaryotic cell evolved from a symbiotic relationship between Archaea and Bacteria Horizontal Gene Transfer = Occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic</p> Signup and view all the answers

<p>Cyanobacteria = Reported to be 3.5 billion years old Hopanoids = Found in the plasma membrane of prokaryotes Sterols = Found in the plasma membrane of eukaryotes Mitochondrion = Evolved from a symbiotic relationship between Archaea and Bacteria</p> Signup and view all the answers

<p>Primitive Microbial Interactions = The organelles of eukaryotic cells arose from prokaryotic cells that had developed a symbiotic relationship with the eukaryote-to-be Endosymbiosis = A relationship between two different kinds of organisms where one lives inside the other Horizontal Gene Transfer = Occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic Transcription and Translation = Have characteristics of Archaea</p> Signup and view all the answers

<p>Stromatolites = Fossilized microbial formations Endosymbiosis = Energy production and chemistry of lipids in cell membrane of eukaryotes more similar to Bacteria Serial endosymbiosis hypothesis = Eukaryotic ancestor possessed a nucleus prior to endosymbiosis with bacterial ancestor of the mitochondrion Symbiogenesis hypothesis = The nucleus evolved after establishment of endosymbiosis</p> Signup and view all the answers

<p>Endosymbiotic Theory = The organelles of eukaryotic cells arose from prokaryotic cells that had developed a symbiotic relationship with the eukaryote-to-be Symbiogenesis hypothesis = Eukaryotic cell evolved from a symbiotic relationship between Archaea and Bacteria Serial endosymbiosis hypothesis = Eukaryotic ancestor diverged from archaeal line and possessed a nucleus prior to endosymbiosis with bacterial ancestor of the mitochondrion Horizontal Gene Transfer = Occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic</p> Signup and view all the answers

<p>Cyanobacteria = Reported to be 3.5 billion years old Hopanoids = Found in the plasma membrane of prokaryotes Sterols = Found in the plasma membrane of eukaryotes Mitochondrion = Evolved from a symbiotic relationship between Archaea and Bacteria</p> Signup and view all the answers

<p>Primitive Microbial Interactions = The organelles of eukaryotic cells arose from prokaryotic cells that had developed a symbiotic relationship with the eukaryote-to-be Endosymbiosis = A relationship between two different kinds of organisms where one lives inside the other Horizontal Gene Transfer = Occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic Transcription and Translation = Have characteristics of Archaea</p> Signup and view all the answers

<p>Stromatolites = Fossilized microbial formations Endosymbiosis = Energy production and chemistry of lipids in cell membrane of eukaryotes more similar to Bacteria Serial endosymbiosis hypothesis = Eukaryotic ancestor possessed a nucleus prior to endosymbiosis with bacterial ancestor of the mitochondrion Symbiogenesis hypothesis = The nucleus evolved after establishment of endosymbiosis</p> Signup and view all the answers

<p>Endosymbiotic Theory = The organelles of eukaryotic cells arose from prokaryotic cells that had developed a symbiotic relationship with the eukaryote-to-be Symbiogenesis hypothesis = Eukaryotic cell evolved from a symbiotic relationship between Archaea and Bacteria Serial endosymbiosis hypothesis = Eukaryotic ancestor diverged from archaeal line and possessed a nucleus prior to endosymbiosis with bacterial ancestor of the mitochondrion Horizontal Gene Transfer = Occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic</p> Signup and view all the answers

<p>Cyanobacteria = Reported to be 3.5 billion years old Hopanoids = Found in the plasma membrane of prokaryotes Sterols = Found in the plasma membrane of eukaryotes Mitochondrion = Evolved from a symbiotic relationship between Archaea and Bacteria</p> Signup and view all the answers