exam 3 ch 18 Flashcards
Plant resins can harden into amber, preserving insects and other biological material
amber and freezing:
extremely dry environments that cause the drying out of organisms
Desiccating environments:
Ground that remains frozen for many years
Permafrost:
Structures are buried in sediments and dissolved minerals either replace the
original mineral content, or precipitate in and around it
permineralization and replacement:
Remains decay after being buried in sediment; Molds consist of unfilled spaces & casts form when new material infiltrates the space, fills it, and hardens into rock.
Natural molds and casts:
Record behavior instead of direct anatomical form
trace fossils:
(taphos = burial) The study of the fossilization process
Taphonomy:
Factors that contribute to the difference between what was once alive and its representation in
the fossil record
Taphonomic bias:
First confirmed life forms, the prokaryotes (no nucleus), evolve.
-Cyanobacteria (Stromatolites) create enough oxygen to accumulate in the atmosphere
Archean Eon 4.0Ga-2.5Ga:
Period in which the Earth & moon were hit more frequently by a higher
number of large asteroids
4.1 to 3.8 billion years Late-Heavy Bombardment:
The pull of the moon slows the Earth’s rotation
tidal Braking:
Water vapor, carbon dioxide, nitrogen, methane, ammonia, but no free oxygen.
-Sun ~92% of current brightness
Eoarchean atmosphere:
-The atmosphere & likely surface, had more intense ultraviolet radiation as ozone could not form
from an anoxic atmosphere
Eoarchean atmosphere:
may have been the primary fuel production method in Eoarchean
Anoxygenic photosynthesis
Photosynthesis that uses hydrogen sulfide as a reductant (instead
of water) to make sugars and gives elemental sulfur off as waste (instead of oxygen)
3.77 Ga Anoxygenic photosynthesis:
First major continent, composed of cratons from Southern Africa and
Australia
3.6 Ga Vaalbara Supercontinent:
A stable part of a continent that experiences minimal deformation over very long periods.
Craton:
First Definitive fossils of archaea and
cyanobacteria
Paleoarchean (3.6–3.2 Ga)
~3.5 Ga:
Layers of compacted sand and microorganisms created by photosynthetic
microorganisms such as cyanobacteria or sulfate-reducing bacteria
3.48 Ga Stromatolites:
Oldest fossils of methane-producing archaean microbes
3.42 Ga fossil threads:
Rocks have Sulfur- isotope ratios indicative of microbial sulfate reduction
3.48 Ga Sulfides:
ATP production that uses sulfate as a terminal
electron acceptor, reducing it to hydrogen sulfide (H2S)
3.4 Ga Microbial sulfate reduction:
Iron sulfide associated with biology because most is produced by bacteria that extract their oxygen from sulfate and produce hydrogen.
Pyrite (FeS₂):
Reduces atmospheric N2 to organic NH4.
3.2 Ga (minimum) Biological Nitrogen fixation:
The key enzyme for biological nitrogen fixation, the only mechanism capable of catalyzing the
reduction of atmospheric N2 into fixed nitrogen known to have evolved
3.2 Ga Nitrogenase evolved:
Oldest fossils of methane-producing archaean microbes
3.42 Ga fossil threads:
Cellular respiration in
which the terminal electron acceptor is carbon (CH4)
Methanogenesis:
Anaerobic archaea that produce methane as a byproduct of their energy
metabolism
Methanogens:
First evidence of photosynthetic production of O2
Mesoarchean (3.2–2.8 Ga):
Carbon dioxide and nitrogen dominate, shrinking amounts of methane,
ammonia, with the beginnings of free oxyge
Mesoarchean atmosphere:
Second supercontinent formed when multiple cratons fused with Vaalbara
3.0 – 2.8 Ga Ur Supercontinent:
Isotopic composition of rocks confirms O2 was present
3.2-2.8Ga Photosynthetic production of O2:
Group of bacteria that obtain energy via oxygenic photosynthesis
Cyanobacteria
suggests oxygenic
photosynthesis may have begun as early as 3.4 Ga
Cyanobacteria Phlogenetic anaylysis
First truly large supercontinent “Kenorland”, evidence of Eukaryotes.
Neoarchean (2.8–2.5 Ga):
First truly large supercontinent that spanned from northern to
southern latitudes
2.7 – 2.4 Kenorland supercontinent:
Ammonia (NH4)from nitrogen fixation is
aerobically (using oxygen) oxidized by nitrifying microbes to nitrite (NO2-) or nitrate (NO3-)
2.7 Ga Aerobic Nitrogen metabolism:
Strongly negative 15N values in carbonate sediments indicate
the generation of biomass from assimilation of NH4, in mildly-oxygenated aquatic settings
2.7 Ga Aerobic Nitrogen metabolism:
Large cells engulfed independent mitochondria and became reliant on their
processes
Endosymbiosis:
DNA is packaged within the nucleus, however mitochondria have their
own circular DNA revealing bacterial ancestry
Mitochondrial DNA:
Possibly the bacteria most closely related to mitochondria.
Iodidimonas:
Most phylogenetic analysis puts it as the most closely related bacterium to mitochondria.
Rickettsiales bacterium:
