Origin of first cell

WHEN Did Life Evolve? Earth was molten during Hadean Then cooled somewhat by 3.9 billion years ago Solid rock & water could remain liquid at the surface

Origin of the Oceans water vapor condenses and falls as rain oceans accumulated salts added over 3.9 billion years as material eroded from continents

oxygen breaks down organic molecules life must have evolved before oxygen abundant Early Archean sediment dark-colored = unoxidized oxidized (rusted) sediment appears about 3.5 billion years ago life must have evolved before 3.5 bya

WHEN Did Life Evolve? oldest (possible) life-forms ~3.5 billion years old life likely evolved between 3.9 and 3.5 billion years ago

How Did Life Evolve ?

Monomers building blocks of life must form for life to evolve how did monomers first form? Amino Acids

Monomer Synthesis Miller and Urey - created “Early Earth Apparatus” early Earth atmosphere in the top electrodes to produce “lightning” primordial pond in the bottom

Results: after a week, primordial pond became primordial soup 12 of 20 most common amino acids synthesized + other stuff next step: polymerization

Polymers chains of molecules proteins carbohydrates lipids nucleic acids

Requirements for Polymerization energy source: to drive reactions protection: from too much energy concentration: to bring materials together so they can react together catalysts: to make reactions happen faster and more efficiently

Energy Source Energy induces chemical reactions volcanoes lightening cosmic rays UV radiation

Protection too much energy can be a bad thing! early organic material protected by: rock ledges, under ice, under thin film of sediment, just under surface of water

Concentration when chemicals are dispersed in water, reactions are less likely to happen concentration brings reactants together evaporation freezing scums droplets, bubbles clay

Concentration - clay clay forms from sedimentary particles called platelets platelets are: very small flat with negative charge on surface

Clay organic molecules are attracted to clay surface concentrate and align Examples: bentonite (kitty litter, mud masks), kaolinite (Kaopectate)

Catalysts decrease amount of energy needed for chemical reactions so increase the rate of chemical reactions catalysts in the body = enzymes Inorganic catalysts often metal ions

Making Cells what is required to make a cell? DNA: passes on genetic code cell membrane: made of phospholipids

Phospholipids each molecule has a hydrophobic end and a hydrophilic end when surrounded by water, fatty acids form shapes where the hydrophobic ends protected on the inside

Protobionts Phospholipid spheres that form naturally polymers and enzymes concentrated inside reactions occur inside protobionts: maintain their structure increase in size over time divide when too large selectively absorb and release compounds metabolize starch store and release energy

Are Protobionts Alive? No they can’t replicate themselves

Replication process by which organisms make genetic copies of themselves asexual reproduction sexual reproduction

Origin of Heredity short strands (50 nucleotides) of RNA assemble naturally replicate themselves if more monomers available zinc, copper act as catalysts