Lecture 2 Flashcards
4.6 BYA
local supernova explosions, heavy meteriote bambardement until 3.8 BYA
4.4 BYA
Oldest mineral; zircon in Australia
Ocean and atmosphere forms (water, methane, sulphur gas, carbon dioxide)
cold and glacial climate
4.0 BYA
oldest rock; Acasta gensis, NWT
3.8 BYA
oldest sediment, Greenland.
- hydrology cycle
- liquid ocean are present
3.8 - 3.3 BYA
origin of life
3.3 - 2.2 BYA
direct signs of cellular organisms
2 things that attribute to the living organism
Genetic: self-replication, heritability (confer evolvability)
Physiological: metabolism, complexity, appropriateness
Theory 1: Special Creation
origin is from hatching of eggs or seeds
believed for a while (displaced by geology and evolutionary biology)
Undirected Panspermia
dispersal of microbes from planet to planet by radiation E or ballistic ejection inside rocks
Objections: low star density, low probability
Directed Panspermia
aliens
Objection: time
Misdirected Panspermia
galactic (galaxy) pollution
Theory 3: Spontaneous Generation
spontaneously generated from putrefaction (process of rotting)
Spontaneous generation requires:
complex organisms arise spontaneously by natural process - self organization
continuous entities link the chemical with the living with natural selection early, taking over from self-assembly
Prebiotic Chemistry
Miller Urey
-electric discharge passing through an artificial atmosphere (methane, CO, NH3) over an ocean produces organic compounds (amino acids & nucleotides)
Two chemical processes to allow life to be possible
growth
replication
for life to happen in prebiotic chem: need inheritance
