History of life on earth Flashcards
Earth and its moon formed
4.6bya ago
Stages through which simple cells were formed
I)abiotic synthesis of small organic molecules
II)joining organic molecules to form macromolecules
III)packaging of macromolecules into protocells
IV)origin of self replicating molecules that eventually made inheritance possible
Micro evolution
How populations change over time
Macro evolution
Large scale changes in large taxonomic groups over long periods of time
Relative dating
Comparing sedimentary strata to find the relative ages of fossil with the assumption those deeper in the sedimentary rock are older than those more shallow In sedimentary rock
Radiometric dating
Finding the absolute ages of fossils by measuring radioactive isotopes and decay products
Half life
Time required for parent isotope to decay
Radiocarbon dating
Most common radio metric dating, measures the carbon isotope 14c and its decay products
Geologic time scale
Is a system of chronological dating used to describe the timing and relationship of events in geologic history
Geologic time scale
Eons, eras,periods, epochs, ages
(Oldest to newest)
Major events in life history
I)first life on earth
II)oxygen revolution
III)origin of first eukaryotes
IV) origin of first multicellular organisms
Stromatolites
Oldest known fossils, they are rocked formed by the accumulation of sedimentary rocks on microbial mats
Microbial mats
Multilayered sheets of prokaryotes
Stromatolites
Date back to 3.5 bya
First life On earth
Prokaryotes most likely bacteria
Oxygen revolution
2.4 to 2 bya
Oldest known eukaryotic fossils
Protists, date back to 2.1 bya
Endosymbiosis
Process where prokaryotic cell is engulfed by the host cell (and over time the engulfed cell becomes a dependent part of the host cell)
Primary endosymbiosis
Engulfed prokaryote developes into a cell structure within a eukaryotic cell
Secondary endosymbiosis
Product of endosymbiosis is engulfed and retained by another free living eukaryote
Evidence for endosymbiosis
I)inner structure of mitochondria and chloroplasts looks like the plasma membrane of prokaryotes
Evidence for endosymbiosis
II)mitochondria and chloroplasts can transcribe and translate their own DNA regardless of the cell they’re In
Evidence for endosymbiosis
III) division and DNA structure in mitochondria and chloroplasts are similar if some prokaryotes
Evidence for endosymbiosis
IV)Their ribosomes are more similar to prokaryotes than eukaryotes