Unit 7 - The History of Life on Earth

space time

13.7 BYA was the universe, 4.6 BYA was the sun and earth

hadean eon

4.6-3.9 BYA, physics is free energy, chemistry is inorganic molecules like H2O, biology #1 is prokaryotic life 3.9 BYA, simplest life is macromolecules, cell, replicate

primordial soup hypothesis

miller and urey: synthesized 20 amino acid monomers, sutherland: synthesized a 2 RNA nucleotide monomer, hanczyc: synthesized lipid cells and replication event

other abiogenesis models

exogenesis hypothesis, clay hypothesis, radioactive beach hypothesis, thermodynamic dissipation hypothesis, polycyclic aromatic hydrocarbon hypothesis

exogenesis

life originated elsewhere in the universe and spread to earth

thermodynamics

when a group of atoms is driven by external source of energy and surrounded by heat bath, it will gradually restructure itself to dissipate increasingly more energy

clay hypothesis

original structure that provided transfer of information and could have been clay type of inorganic substance

polycyclic aromatic

mediated synthesis of RNA

radioactive

radioactive material on beach

biology #2

photosynthesis, 2.7 BYA

proterzoic eon

2.5 BYA, biology #3 is eukaryotic life

endosymbiosis theory

mitochondria and chloroplasts, contain own DNA, small circular, double membrane, replicate independently, binary fission, cell doesn’t make them

biology #4

multicellular life, protists, plants, fungi, animals

biology #5

colonizing land

diversification — extinction —

diversification — extinction

3/5 mass extinctions

450 MYA 90%, 250 MYA 96%, 65 MYA 75%

6th mass extinction

currently, 100-1000X normal extinction rate