Lecture 2: Origin of LIfe Flashcards
protoplanetary disk
-large rotating cloud of dust, rocks, and gas
formation of our sun
-presuure within the central mass of the protoplanetary disk triggers nuclear fission
protoplanet
-a large body of matter in orbit around the sun or a star and thought to be developing into a planet
precambrian supereon
- so vast it’s considered a supereon
- found early multicellular life
paleozoic era
-covers time of soft-shelled mussels and hardshelled organisms to land being dominated by sophisticated reptiles and plants
mesozoic era
- first mammals
- age of reptiles (dinosaurs)
- ends with K-T extinction
cenozioc era
-age of mammals (including humans)
early hadean eon
- no oceans
- no O2 in atmosphere
- no protective atmosphere
- lots of molten lava
- no life
late hadean eon
- no ozone layer to protect against UV rays
- oceans form as planet cools and clouds form
- no life
archean eon
- atmosphere forms from:
- ->gas released by volcanoes
- ->astroidal bombardment creates crack on Earth and steam escapes from cracks
- originally had methane, CO2, water, in atmosphere
- any free oxygen had to be bound to hydrogen or other elements
which eons were located in precambrian supereon?
- hadean
- archaean
- proterozoic
unicellular vs multicellular
U: single-celled, less complex, mainly bacteria
M: multiple cells, more complex, more developed organisms
stromatolites
-layeredbands of fossilized bacteria (cyanobacteria)
bacterial fossils
-in fossil stromatolites, the layers that are formed as biofilms of cyanobacteria die and others take their place
archean fossils
-trace fossil: pathway in dirt or terrain that indicates movement
trilobites
-very first of the hard-shelled organisms
archeocyathids
- vsrious Cambrian sponge-like animals
- believed to be the base of the animal tree
1st land plants
- carpet moss
- paleozoic era
1st land animals
-early amphibian tetrapod; fish evolved legs and started to walk on land
permian extinctinon
- aka The Great Dying
- up to 96% of all life went extinct
- only mass extinction of insects but largestin history
- O2 levels drop rapidly
- ends Paleozoic Era
age of repitles
- dinosaurs appear
- mesozoic era
1st mammals
-morganucodon watsoni
K-T extinction event
- catastrophic event occurred
- asteroid impact couldve triggered increased volcanic activity
- ->more dust and ash in the air dec. sunlight available hindering photosynthesis thus mass destruction of earth’s ecology
K-T boundary
- thin band of sediment that only non-avian dinosaurs are formed under (fossils could be found)
- found on mountains
geologic clock
- shows the history of time in a typical clock face
- helps us revisualize the passage of time
first step to form life
-abiotic synthesis of organic materials
second step to form life
-formation of polymers–> chains of things to form bigger things (occurs spontaneously)
third step to form life
- formation of protobionts
- hydrophillic heads and hydrophobic tails, but the heads attacht to water and chemicals
fourht step to form life
- origin of hereditary material
- 1st life probably in RNA world can be formed abiotically, can replicate itself, zinc around–> forms clay DNA cannot replicate itself, has catalytic properties–> can be a catalyst and also carry genetic info.
Miller and Urey’s experiment
- trying to prove that the conditions that existed on primitive Earth were capable of leading to organic compounds
- used water, H2, CH4, NH3 which were the building blocks of life
- their results proved that the assumed conditions of earth can lead to organic compound and eventually to life
monomer
- the single units that make up polymers
- three types are: simplesugars, nucelotides, and amino acids
polymer
-a long molecule consisting of many similar or identical building blocks linked by a dehydration rxns
protobionts
-systems that are considered to have possibly been the precursors to prokaryotic cells
four reasons we think there was originally a RNA world
1) easily forms abiotically than DNA
2) can replicate itself, more likely in the presence of zinc
3) has hereditary info
4) has catalytic properties (can act like an enzyme)
four reasons we think there was originally a RNA world
1) easily forms abiotically than DNA
2) can replicate itself, more likely in the presence of zinc
3) has hereditary info
4) has catalytic properties (can act like an enzyme)
viroids
- raw bits of RNA
- causes diseased plants
- may be the clue to the RNA world and responsible for modern life
cyanobacteria
- live on stromatolites
- first prokaryote
- believed to be 1st organisms bc they can perform photsynthesis
morganucodon watsoni
- one of the first mammals
- rat looking rodent
- mezoic era
the importance of clay
- clay is positively charge and rich in iron and zinc
- monomers all have negatively charged portions and are attracted to the clay and that might’ve put them in close enough proximity to form chains
