Origin of Life Flashcards
Origin of Life
Began 3.5 -3.9 billion years ago
Miller-Urey Experiment
Provided evidence that organic molecules needed for life could be formed from inorganic components
Steps to Life Formation
Earth and atmosphere formed
Seas formed
Complex molecules synthesized
Polymers and self replicating molecules synthesized
Organic molecules concentrated and isolated into protobionts
Primitive heterotorphic prokaryotes formed
Primitive autotrophic prokaryotes formed
Oxygen and ozone layer formed, abiotic chemical evolution ended
Eukaryotes formed
Earth and Atmosphere formed
Atmosphere formed from volcanic outgassing the molten interior of planet earth
Had a reducing atmosphere
Reducing Atmosphere
Early earth contained no O2, but it contained CO, CO2, H2, N2, H2O, S, HCl, and HCN
Cyanobacteria responsible for adding oxygen to atmosphere
Seas Formed
Earth cooled down, causing gases to condense, resulting in water and minerals that make up the sease
Complex Molecules Synthesized
a.a., acetic acid, formaldehyde formed
Monomers formed
Formation of simple molecules made possible by absence of oxygen (oxygen is very reactive)
Organic soup
Inorganic molecules made into organic molecules via energy from UV light, lightning, radioactivity, and heat
Polymer and Self Replicating Molecules
Monomers formed polymers via dehydration/condensation reaction
Proteinoids formed
Protenoids
Abiotic polypeptides formed by allow a.a. to dehydrate on hot, dry substances
Protobionts
Self organized sphere of lipids that provided border where chemical reactions could take place (like a cell)
Precursor of cells
Unable to reproduce
Microspheres and Coacervates
Abiotically produce protobionts
Heterotrophic Prokaryotes
Can’t make own food
Obtain energy by consuming other substances
i.e. Pathogenic bacteria
Organic soup made from inorganic material was the original source of organic material for these heterotrophs
Natural selection occurred over time for competing cells
Autotroph
Heterotrophs mutated and gained the ability to make their ow food (from light or energy from inorganic substances)
i.e. Cyanobacteria (photosynthetic bacteria)
End of Abiotic Chemical Evolution
Autotrophs release oxygen as a byproduct
Oxygen reacted with UV formed the ozone
Ozone absorbs UV light, preventing it from reaching the surface of the planet
Prevented abiotic synthesis of organic molecules (UV light was the major source of energy)
Endosymbiotic Theory
Eukaryotic cells originated from various prokaryotes who, when together, formed a mutually beneficial association. Therefore, mitochondria, chloroplasts, etc. moved inside a prokaryote to form the eukaryote
Evidence for Endosymbiotic Theory in Mitochondria/Chloroplasts
Have circular DNA with no proteins like bacteria/cyanobacteria
Ribosomes resemble bacteria and cyanobacteria
Reproduce independently of the eukaryotic cell in a binary fission fashion (like in bacteria)
Double membranes might be from prokaryote surrounding the organelle
Thylakoid membranes similar to photosynthetic membranes in cyanobacteria
Evolution of FIsh
Jawless fish—-> cartilaginous fish—-> lobe finned fish
Evolution of Chordates
Notochord Head Vertebral column Jaw and mineralized skeleton Lungs/lung derivatives Lobed fins Limbs with digits Amniotic eggs Production of milk
Notochord
Lanceletes and tunicates
Head
Hagfish
Vertebral Column
Jawless fish (Class Agnatha)
Jaw
Class Chondrichtyes
i.e. sharks
Lungs
Ray finned fish
Class Osteichthyes
Limbs with digits
Amphibians
Class Amphibia
Amniotic eggs
Reptiles (Class Reptilia)
Birds (Class Aves)
Production of milk
Mammals (Class Mammalia)
