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THE ORIGIN OF LIFE, unnamed, Louis_Pasteur, 1_6, picture11316726416916,…
THE ORIGIN OF LIFE
The problem of spontaneous generation
Most widespread believes was: spontaneous generation.
Examples:
Maggots that appear in decomposing meat.
Frogs that grow in mud and stagnant water.
The first idea:
Ocurred in 1668
The doctor: Francesco Redi
Minuscle organisms existed in all cultures.
It regnited the controvery regarding spontaneous generations.
Other idea
Chemist: Louis Pasteour
Ocurred in 1859.
All living things come from another living thing.
The experiments
Redi's experiment
Insert two pieces of meat into two containers.
Opened: Maggots. Fly larvae.
With gauze: Not maggots
Pasteur's experiments
Poured beef broth into two flasks
No broken neck: Not descomposed
Broken neck: Descomposed
Modern
theories
The oldest came from Isua, a region in Greenland
Consists of: Chemical remains dating back about 3.8 billion years ago.
Models that explain the presence of life in Earth
Pansermia
Argues that life originated in space and was carried to the Earth by meteorites
Abiogenesis or prebiotic synthesis.
Combine several theories
3 stages:
Simple organic molecules from inorganic ones.
Development of complex molecules.
Appearence of first molecule: chemical evolution.
Include:
Theory of hydrothermal vents
More widely accepted one
Suggest: Life started in hydrothermal vents which are located in seafloors.
Vents are protected from solar radiation and sheltered from forces as wind and strong currents.
Forces rich in methane, H suphide and iron.
Much life form and are resistant to high temperatures. Also oldest organisms and located in food chain in ecosystems.
Primordial soup
Described a primitive oxygen-free atmosphere. Composed of: methane, hydrogen...Ultraviolet radiation and electrical energy from violent storms: energy source. Would develop membranes: produce the first cell.
Alexander Oparin
John Haldane
