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Timeline leading to beginning of LIFE
Universe began with the Big Bang
Our solar system began
The earth formed
(enough for the outer layers to solidify and
4 - 3.5 BYA
: Life emerged
Earth formed 4.55 BYA
For the first 1/2 billion years after earth formation it was too hot to allow water to accumulate on its surface.
By 4 BYA the Earth had cooled down enough for the outer layers of the planet o solidify and for oceans to begin to form.
Condition on early Earth?
Little or no Oxygen in the atmosphere
Atmosphere full of H-rich Gases
SH2, NH3, and CH4 etc.
Also carbon dioxide, carbon monoxide, & gaseous nitrogen
Subject to Meteor bombardments because early solar system full of debris
Lots of Volcanic activity & intense Electrical storms
No Ozone = lots of UV radiation exposure
Name the four overlapping stages for the beginning of life. (in order)
Origin of organic molecules
were produced prior to the existence of cells
may have formed on the surface of clay
3. Cell-like structures may have originated when polymers were
enclosed by a boundary
4. Cellular characteristics may have evolved via chemical selecion, beginnning with an
Define "Chemical Selction"
occurs when a chemical within a mixture has special properties or advantages that cause it to increase in number compared to other chemicals in the mixture
preserved remains of past life on earth
Facts about "Fossils"
Many rocks with fossils are sedimentary
Sediments pile up and become rock
Organisms buried quickly, hard parts replaced by minerals
Older rock is deeper, older organisms are deeper in rock bed
Fossils dated using elemental isotopes in rock
Half-life – length of time required for exactly one-half of original isotope to decay
Measure amount of a given isotope as well as the amount of the decay product
Usually nearby igeneous rock dated
Why move from an RNA world to DNA/RNA/protein?
DNA is less likely to suffer mutations
Relieve RNA of the info storage role so that it can do other functions
Proteins have greater catalytic potential, are more efficiency, provide structure & transport
Bio113 unit one, chapter 22 the origin and history of life