The Tree of life

bio lecture 2

when was the earth formed

approximately 4.6 billion years ago

what was the early earth atmosphere like?

1.) thick with water vapor; little to no oxygen

2.) constant volcanic explosion; hot and constantly bombarded meteorites

3.) atmosphere made with harsh gasses

4.) No life possible for 200 - 300 million years

what is life?

matter that undergoes biological processes

life is made up of what macromolecules?

carbohydrates, Lipids, Proteins, Nucleic acids

what are macromolecules of life made up of?

made of simple organic molecules that are not present in early earth

Where did life originate?

in the primordial soup

conditions of early earth when earth cooled

1.) water vapor condensed to form oceans

2.) elements added to the environment ( carbon, nitrogen,hydrogen,etc)

3.) added energy (lightning and intense UV rays

where did early life most likely form?

near submerged volcanos &deep sea vents

what Is the Miller - Urey Experiment (1953)

Replicates conditions of early earth and primordial soup and created evidence of of simple organic compounds (formaldehyde and hydrogen cyanide) and found more complex molecules (amino acids and hydrocarbons)

what are the 4 stages of early earth evolution to life now?

1.) abiotic synthesis of organic molecules (amino acids and nucleotides)

2.) joining of small molecules into macromolecules (amino acid polymers)

3.) packaging of molecules within membranes - protocols

4.) the origin of self-replicating molecules (likely RNA)

what is the classic timeline?

formation of earth → stable hydrosphere → prebiotic chemistry → pre-RNA world → RNA world → first DNA/protein life → last universal common ancestor

what is a fossil?

Trapping of dead organisms in a sediment

what can the fossil records tell us?

about the order of death through Strata but not exact age (it is biased and incomplete)

what is radiometric dating?

radioactivity decay of isotopes

what are isotopes half lifes?

number of years it takes for 50% of the original sample to decay

unaffected by temp, pressure, and other environmental factors

what are the 4 EONS

1.) Hadean

2.) Archean

3.) proterozoic

4.) Phanerozoic (current EON)

what are the 3 ERAS

1.) Paleozoic

2.) Mesozoic

3.) cenozoic (current)

Hadean

beginning of the earth, contained harsh warm climates, life started to appear closer to the end of it (4.0 bya)

Archean

water world, reducing atmosphere with not much oxygen, exclusive prokaryotic life

proterozoic

atmospheric oxygen increases, eukaryotic and multicellular life appears

Phanerozoic

life explodes and creates mass diversity

what is a prokaryote?

a single-celled organism lacking membrane-enclosed nucleus and membrane enclosed organelles

what are stromatolites?

microbial mats that form rick like structures

their complexity suggenst that prokaryote life evolved earlier (4.2 bya)

cyanobacteria

began photosythesis, changed earths atmosphere

what are eukaryotes?

organisms Smith a membrane enclosed nucleus and membrane enclosed organelles

when did multicellularity begin and then expand?

1.5 by a through small algae, it expanded after the earth thawed (570 mya; snowball bath hypothesis)

what is the Cambrian explosion

Rapid diversification of marine life (541 mya)