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The History of Life on Earth - Coggle Diagram
The History of Life on Earth
Conditions on early Earth made the origin of life possible
Observations and experiments in chemistry, geology, and physics have led scientists to propose one scenario that we’ll examine here. They hypothesize that chemical and physical processes could have produced simple cells through a sequence of four main stages:
The joining of these small molecules into macromolecules, such as proteins and nucleic acids
The packaging of these molecules into protocells, (droplets with membranes that maintained an internal chemistry different from that of their surroundings)
Protocells had an internal chemical environment surrounded by a membrane, which protected its environment form a hostile habitat, where somehow it was well to prudence DNA. (Bilayer)
The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases
The origin of self-replicating molecules that eventually made inheritance possible
In 1953, Stanley Miller, working with Harold Urey, testes these steps, some universities were able to get organic compounds, they had also found numerous amino acids formed around volcanoes.
The first Earth atmosphere had little oxygen and was filled with compounds released from volcanoes.
volcanic atmosphere and alkaline vent hypotheses show that the abiotic synthesis of organic molecules is possible under various conditions.
Another source of organic molecules may have also been meteorites
Abiotic synthesis of macromolecules (where macromolecules or other organic molecules form on their own)
RNA came before DNA, RNA plays a central role in protein synthesis, but it can also function as an enzyme-like catalyst (ribozymes) Some ribozymes can make complementary copies of short pieces of RNA, provided that they are supplied with nucleotide building blocks.
Key events in life’s history include the origins of unicellular and multicellular organisms and the colonization of land
The rise and fall of groups of organisms reflect differences in speciation and extinction rates
Major changes in body form can result from changes in the sequences and regulation of developmental genes
Evolution is not goal oriented
The fossil record documents the history of life
Fossil record t(he fossil record is based primarily on the sequence in which fossils have accumulated in sedimentary rock layers, called strata)