How the earth was created Flashcards
1
Q
Deep time
A
- Geologic time is divided into four eons
- Eons are subdivided into eras, which are further subdivided into periods
- Geological evidence suggests a meteor hit the earth 4.6 billion years ag (BYA)
- No rocks exist from hadean eon (first 500-700 million years of Earth’s history
- Hadean Earth was pummeled by asterioids, which could potentially vaporize enture oceans
- When meteor hit, the rocky mantle melted ad atmosphere temperature exceeded 2000c
2
Q
Changes in Earth in geological time
A
- CO2 levels shifted and affected temperature
*Early at
3
Q
Early organic molecules
A
- how first organic molecules formed is not known
- Hundreds of thousands of meteorites and comets slammed into early earth; some may have carried
4
Q
Early earth’s atmosphere
A
- few geochemists agree on exacr composition of early atmosphere
- Popular view of early atmosphere
- carbon dioxide(CO2)
- Nitrogen gas (N2)
- Water vapor (H2o)
- Hyferogen gas (H2)
- Other sulfur, nitrogen and carbon compounds
- Atmosphere reducing
5
Q
Miller- Urey experiment #1
A
- In 1953, miller and Urey did an experiment that reproduced ealy atmosphere rich in hydrogen with no oxygen gas
6
Q
Miller- Urey experiment #2
A
- Found within a week that methane gas (CH4) converted into other simple carbon compounds
- compounds combined to form simple molecules and then more complex molecules
7
Q
Emeregence of metabolic pathways
A
- Primitice organism may have been autotrophic built what they needed
- RNA may have been first genetic material
- ribozymes are RNA sequences with enzymatic function: ; early cells may have used RNA to catalyze synthesis peptides from RNA sequence
- Lipid bubbles could increase
8
Q
Conditions on early Earth
A
- Seems likelt that Earth’s first organism emrged and lived at very high temperatures
- Around 3.8 BYA ocean temperatures dropped to 49 to 88c
- first organism emerged around this time
9
Q
Fossil evidence of life
A
- Evidence of life during the Archean in the form of microfossils is difficult to find and interpret
10
Q
Microfossils
A
- Microfossils are fossilized forms of microscopic life
- oldest are 3.5 billion years old; seem to resemble present-day prokaryotes
- fossils
11
Q
Stromatolites
A
- Stromatolites are mats of cyanobacterials cells that trap mineral deposits
- indirect evidence for ancient life
- oldesr are 2.7 billion years old
- modern forms are also known
12
Q
Isotopic data
A
- Living organism incoporate 12c into their cells before other carbon isotopes
- work has been done dating and analyzing carbon compounds in the oldes rocks, looking for evidence of life; carbon fixation active as long as 3.8 BYA
- Ancient carbon fixation via Calvin Cycle or a reductive version of the krebs cycle
13
Q
Biomarkers
A
- Look for evidence of ancient organic molecules of biological origin
- proven difficult to find
- hydrocarbons derived from fatty acid tails of lipids were found in ancient rocks
- analyzed for carbon isotope ratios to indicate
14
Q
life Changes Earth
#1
A
- Oxygenic photosynthesis produced atmospheric 02
- 200 milion year lag between the origins of photosynthesis and substantial level of 02
- Iron oxide in the oceans
- 02 in the atmosphere it interacted with ultraviolet (UV) radiation from the Sun and formed 03 (ozone)
15
Q
Life Changes Earth #2
A
Did plants contribute
