Module 5 Flashcards
When was Planet Earth formed
4.6 Billion years ago
Why is Earth a habitable place?
- Surface was molten lava (temperatures 700-1200)
- Bombardment by meteors and lightning
- Volcanoes released gases
- No free oxygen at first
What did the volcanoes mostly release
Nitrogen
How lond did it take for water to accumulate
First half billion years (500 million years)
EONS in order
Haden
Archaean
Proterozoic
Phanerozoic
When did first fossil life occur
3.5 million years ago
Haden
First EON
Earths gravity changed
Atmosphere formed, gases from volcanic activity retained
When was earth inhospitable for life
Haden
Time period of Haden
4600 million - 3600 million
During which EON did first life form
Archaen
Time period of Archean
3600 - 2500
Proterozoic
2500 million - 543 million
Phanerozoic
543 million to present
When did the Earths surface begin to cool
Between 4.6 to 2.5 billion years
During Haden and Archean periods
EONS in order
Haden
Archean
Proterozoic
Phanerozoic
Eras of Phanerozoic eon
Cenozoic
Mesozoic
Paleozoic
Periods of EONS
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
In which EON did Oceans begin to form
Haden
In which EON Rhodinia formed
Proterozoic
Rhodenia
Land forming
First land masses raised above oceans by __________ movement in ____________ EON
Tectonic plate , Early Archean
Abiogenesis
Origin of life
Life arose from ___________
non living matter
Panspermia
Hypothesis which was rejected
Hypotheis of Panspermia
The earth was seeded with primitive life forms form other planets; transported by a meteors, asteroids or comets
First living Organism
LUCA
Characteristics of LUCA
Unicellular
Prokaryote
Extermophile
Asexual reproduction
Heterotrophic
First Life began in __________
Oceans
Ancient Earth was a ____________
Water world
What was needed to occur to form a living cell
- Organic Molecules (nucleotides and amino acids)
- Nucleotides and amino acids combined to form DNA, RNA and proteins
- Polymers became enclosed membranes (Protobiont)
- Protobionts evolved cellular properties
Protobiont
Building the characteristic of living things
Hypotheis for Origin of Organic molecules
Extraterrestrial Hypotheis
Reducing atmosphere Hypothesis
Deep sea vent hypothesis
Extraterrestrial Hypotheis
Organic compounds transsported to Earth from other planets in our solar system with the same molecules
Reducing Hypothesis was proposed by
Aleksandr Oparin
John (J.B.S.) Haldane
Reducing Atmosphere Hypothesis
Earth had a reducing atmosphere containing H2, CH4, NH3 and water vapour with high energy sourced led to the formation of organic molecules from inorganic molecules
No OXYGEN was present
Primordial soup
Organic molecules became concentrated in oceans producing a prebiotic soup
Abiotic synthesis is a _______ process
Slow
How was reducing hypothesis tested
Miller - Urey Experiment
Conlusion of Miller Urey experiment
YES ORGANIC MOLECULES
NOOOOOO FORM OF LIFE
Deep sea hydrothermal vents
Hotsprings produced by volcanoes located as spreading ridges and convergent plate boundaries
Discovered in 1970s
Deep sea Hydrothermal vent hypothesis
Formation of Organic molecules (chemical building blocks of life)
Who came up with Depp Sea Hydrothermal Vent Hypotheis
Gunter Wachtershauser
Deep sea hydrothermal vents
Emit bursts of mineral rich water at 400 degreed
Vent fluids
CO2 + H2 + CH4 + H2S
Black Smoker System
Interaction of seawater and vent fluids
Mineral rich water (400 degrees celsius)
Magnetic Volatiles
CO2 + H2O + He + CO
Yields of Black smoker system
CO2, H2, CH4 and H2S
Lost City System
Yields limestine
More Alkaline, less acidic than black smoker system
More suitable location of first life
Criteria of formation of organic molecules from inorganic molecules
- Organic molecules became concentrated around deep sea vents producing primordial soup
- Abiotic synthesis (formation) of these molecules is a slow process
- No oxygen was present, so there was no oxidation (breakdown) of organic molecules
Were the first organisms Autotrophic and Heterotrophic
Anaerobic Heterotrophs became simpler for primitive cells to use
Anaerobic Chemoheterotrophs
Metabolized pre existing organic molecules
Modern Heterotrophs are mostly aerobic eukaryotes that metabolize pre existing organic molecules by oxidation
Anaerobic Chemoautotrophs use ____________
Chemosynthesis
Process of making methane
Methanogenesis
Methanogens are usually ______________
Extremophiles that live in environments such as volcanic hot springs and deep sea hydrothermal vents
Anaerobic Photoautotrophs
photosynthesis
or use the light produced form heat form underwater volcanic activity
Some ______________ bacteria can photosynthesize using the dim glow of light produced by sea vents
Green sulphur
Anerotbic photoautotrophs use
Hydrogen Sulfide
Requires light
Strictly anaerobic
Anoxygenic photosythesis
Fixing CO2 to compounds
No oxygen is produced
Example aerobic photoautotrophs
Cyanobacteria (Anabena)
Aerobic photoautotrophs
Creates lots of free oxygen
Caused crisis as huge amounts of toxic O2 released
Oxygen is poisonous to __________
An aerobic purple bacteria
Stromatolites
3-3.5 Billion years ago
Microbial mediated rocks
Community of microbes forms mats and secreted a mucus that traps sedimentary grains, cementing them into layers. The upper part of the mat requires photosynthesis, the mat migrates upwards, leaving the layers
Where are stromatolites found
Hot and hyper saline environments
Why are cyanobacteria dope?
- Most ancient aerobic photoautotrophs
- Present 3 - 3.5 billion years ago
- most dominant life form for more than 1.5 million years
2 significant impacts off cyanobacteria
- Produced organic molecules from CO2
- Produced O2 as waste product
- Played a key role in Eukaryotic evolution
Advantage of producing organic molecules from CO2
Prevented depletion of organic food stuffs that would have been exhausted if there were only heterotrophs
When new O2 levels increased
Early Proterozoic