Flashcards in Origin of Life on Earth Deck (26)
What is life?
Is a virus considered life?
No. They reproduce, but don't grow and don't metabolizes.
How do humans gain knowledge?
-trial and error, 100% of pop. does it
Religious and Spiritual
-belief w/ no dissent, self-perpetuating, 98% of pop.
-based on fact/reason, dissent encouraged, less than 1% of pop. engages in this
What is the belief in spontaneous generation?
Belief in the 1800's that non-life spontaneously created other life (rotting meat=flies) (Broth heated, cooled, and bacteria grows)
Who disproved the theory of spontaneous generation?
-Flask with curved tube out of the end.
-Bacteria and dust gets trapped in S-curve.
-When tilted, the bacteria/dust makes contact with broth=growth
What is the primordial soup hypothesis? From whom, does it originate?
That life evolved from simple organic compounds present on earth at the time of its infancy.
Oparin and Haldane came up with it.
What are the basic elements of the primordial soup hypothesis?
-earth had a reducing atmosphere
-gases reacted with energy sources, yielding organic compounds
-compounds in seawater reacted further to form polymers
-polymers became organized to form earliest life
How old is the earth and how do we know?
4.6 billion years old
-We know through radiometric dating of minerals in rocks
-Igneous (not many as old as earth), meteorite, moon rocks
-Radioisotope to decay product half life
Why aren't all igneous rocks the same age on earth?
How do we know what earth was like when life arose?
How did volcanoes contribute to the primordial soup hypothesis?
Volcanoes spewed ammonia, methane, water, and hydrogen gas into the atmosphere.
-Lightning energy reacted with HCN+C2H2 to produce carbon compounds in water which eventually led to life
-CO2 created greenhouse effect and created atmosphere
who tested the Oparin/Haldane primordial soup theory? What were the results?
1953-Stanley Miller-Urey experiment
-boiled water, and let electrical discharge go across container with CH4, NH3, H2O, H2.
-Gases go through condenser, and collected sampled had building blocks of life
How were processes of creating life possible enhanced?
Hyrdrothermal vents provide high water temperature suitable for organic chemistry
What stage was life in 3.5-3.8 bya?
-all life present used anaerobic metabolism
-primordial soup food grows thin
-origin of photoautotrophs b/c primordial soup running out
-O2 created absorbed as rust
What is the primordial soup?
Building blocks of life created when lightning energy combined with gases in the atmosphere
-these building blocks went into the ocean where they
1) combined to form life or
2) underwent anaerobic fermentation to be used as food
Where could early life live (3.5-3.8 bya)?
deep in the water or in shade b/c no O3 layer to block UV radiation
Anaerobic photosynthetic bacteria developed as a result of the primordial soup food running out 2.8bya. What were the results of this?
Photosynthetic bacteria utlized abundant CO2 in atmosphere to produce sugar which was used as food and O2 a strong oxidizing agent.
-Fe2+ was an oxygen sponge and reacted with O2
to produce rust so O2 didn't oxidize everything
-Produced Fe3+, which is now found in banded iron formations and used in production
What did earliest life look like?
Earliest life was microbial
-Anaerobic metabolism of primordial soup molecules
-Glycolysis has very low yield so life grew slowly
What is the origin of photosynthesis?
Cyanobacteria in deep water use sunlight to make their own sugar and use anaerobic glycolysis to use it which produced oxygen
1.8 bya the ferrous iron, Fe2+, runs out. What occurs?
-O2 slowly makes it into atmosphere
-O2+Sunlight=O3 layer begins to form making surface waters and land less deadly
-O2 is deadly to anaerobes which either kills them off, forces them to areas w/o O2, or forces evolution of aerobic heterotrophs and aerobic autotrophs
What occurred to life from 1.8-1.4 bya?
-first O2 in water and air
-ozone layer starts forming
-advent of sex
-biodiversity begins increasing
What is the result/advantages of aerobic metabolism evolving?
lifeforms have 10x cellular energy
-more energy from oxidative metabolism
-faster growth and reproduction
-more diversity from sexual reproduction
What are the two types of reproduction and how doe they both accomplish genetic diversity?
-genetic diversity on which natural selection could operate
-only through random mutation
How did eukaryotes evolve from prokaryotes?
What occurred 700-540 mya?
-origin of metazoa
-O2 levels surpass 10%