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22 Cards in this Set

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show evidence of ancient prokaryotic life. banded domes of sedimentary rock that are strikingly similar to layered mats formed today in salt marshes and some warm ocean lagoons by colonies of bacteria and cyanobacteria.
2-3 billion years ago, prokaryotes merged into arachae and bacteria groups
produced by early photosynhthetic prokaryotes=aerobic atmosphere
eukaryotic fossils
oldest are 1.7 billion years old, but cells probably evolved a hundred millions years earlier. prob evolved from symbiotic communities of proks
large, disparate group of unicellular eukaryotes and some closely related multicellular organisms.
plants, fungi and animals
arose during precambrian. plants from green algae, fungi and animals from hetertrophic unicellular organisms. fungi closely related to animals
for 90% of earths existence...
there was only life in the water
symbiotic plant roots and fungi
move onto land depended on this association, transformed landscape and created new oppurtunities
life developed from nonliving materials that became ordered in molecular aggregates that were eventually capable of self replication and metabolism
chemical evolution in 4 stages
1. the abiotic (nonliving) synthesis and accumulation of small organic molecules or monomers such as amino acids and nucleotides
chemical evolution in 4 stages
the joining of these monomers into polymers including proteins and nucleic acids
chemical evolution in 4 stages
the aggregation of abiotically produced molecules into droplets, called protobionts, that had chemcial charecteristics different from their surroundings
chemical evolution in 4 stages
the origin of heredity (which may well have been under way even before the "droplet" stage)
earth favored chem. reactions that synthesized organic compounds from inorganic precursors present in the early atmosphere and seas
cannot happen in modern world because of oxygen and photosynthetic life. not conducive to spontaneous synthesis of complex molecules because O2 attacks C bonds.
gases present in old world
volcanoes emit CO, CO2 N2 and water vapor
substratum for the polymerization reactions prerequisite to life. concentrates amino acids and organic monomers from dilute solutions because the monomers bind to chargedt siteson the clay particles
provides a charged surface and the formation of this mineral from iron and sulfur yields electrons that could support bonding between organic molecules to form more complex products
aggregates of abiotically produced molecules. not capable of precise reproduction but maintain internal chem environment diff from surroundings
first DNA molecules
first DNa molecules were really short strands of RNA that began self replicating in the prebiotic world
RNA catalysts that remove introns from Rna and synthesize new RNA
RNA evolution
in a particular environment, RNA molecules with a certain base sequence are more stable and replicate faster with fewer errors
some organic molecules reached the early earth from space