A2.1 Origin of Cells

Conditions of early earth

no oxygen, high concentration of methane and CO2, high temperatures, no ozone, more lightning

Cell theory

cells are the smallest unit of life, all living things are made of cells, cells come from pre-existing cells

LUCA

Last Universal Common Ancestor

Evidence for LUCA near hydrothermal vents

obligate anaerobe (did not use oxygen), chemoautotroph (made its own food from chemicals), able to live in extreme heat

Chemical evidence

presence/ age/ number/ type of isotopes

Fossilized biomolecules

molecular fossils of lipids and other organic molecules

Fossil evidence

relative dating

Genetic evidence

genetic mutations can be used to estimate age

Miller and Urey experiment

recreated conditions of early earth and got organic molecules that couldn’t polymerize in their conditions

Evidence for RNA as original genetic material

self-replicating, stores genetic info, acts as an enzyme

Pasteur’s experiment

proved the theory of the spontaneous origin of cells wrong; three swan-necked flasks, closed environment had no growth, open air environment had growth, tilted environment had growth