Origin of Life
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What is necessary for the formation of organic molecules? and why?
could have formed by from simple molecules
first organic compouinds formed near submerged volcanoes; Ammonia, carbon dioxide, methane, water vapor, and hydrgen gas ( released by volcanic activity )
- gases have 4 key elements of an organic molecule (C,H,O,N) present and the absence of free oxygen in the atmosphere allowed the formation of organic molecules.
how did the absence of free oxygen in the atmosphere allow for the formation of organic molecules?
breaks what holds the atoms together(chemical bonds); oxygen destroys the chemical bonds
why was there lightning from frequent, intense electrical storms and UV radiation from the sun?
no o-zone layer, which protects from uv light
how did Miller-Urey simulate the primitive conditions of earth in a laboratory setting?
-In the aparatus- showed the primitive atmosphere, put in gases (CH4, CO2,NH3,H2) to stimilate atmosphere
-used electrodes that discharge sparks as source of energy ( lightning simulation)
-used heated water to simulate ocean
simple organic building blocks polymerized to form more complex and stable organic molecules how?
when ocean spashed magma, caused it to evaporate and molecules become more condensed
What are protobionts?
all concentrated water molecules that repel back fat molecules, non living, predecessors of living cells, form spontaneously
- collections of abiotically produced molecules surrounded by a membrane-like structure
how do protobiont form spontaneously?
- from abiotically produced organic compunds
example: certain small membrane bounded droplets called liposomes can form when lipids or other organic molecules are added to water, the hydrophobic molecules in the mixture organize the bilayer at the surface.
lipsosomes can reproduce and perform simple metabolic reactions.
how do protobionts show signs of life?
- 1. fat can grow in size, by water and molecules to enter (GROWTH)
- 2. once it gets to certain size it splits and 2 strands of DNA form
- 3. makes 2 protobiont, almost like cell division
- 4. responds to stimuli and inside negative and outside positive ( if you touch droplet, charge difference reverses )
- 5. excitability
RNA was the first important molecule in protobionts why?
- 1. its genetic material has information like DNA
- 2. replicates itself; if leave free sloating can carry out complementary base pairing
- 3. speed up chemical reaction (same as enzyme reaction)
DNA replaced RNA as the primary genetic material, why?
- RNA is just a single stranded strand, DNA is double stranded helix, which means stronger and more stable
- -DNA replicated more accurately
For example, can cut out section of DNA and still repair b/c of double stranded
Prokaryotes were the first cells on earth, why?
b/c they are so simple, have proof from fossils, no nucleus, no membrane bound organelles, no ER, no golgi
what is the autogenous model? explain.
how organelles form by the infolding of the cells own plasma membrane
Ex. ER, golgi, nuclear membrane
what is serial endosymbiotic model? explain.
more complex; engulfing of photosynthetic bacteria -> cyanbacteria, tep formation and bringing bacteria and co exist with the other bacteria
-The proposal that plastids, mitochondria, and possibly also cilia and flagella arose from symbiotic prokaryotic organisms living within a eukaryotic host cell.
explain how chlorplasts and mitochondia resemble prokaryotes?
prokaryotes: circular DNA and ribosomes, splits and makes copies of DNA by binary fission
BOTH: same size
Mitochondra: circular DNA and ribosomes, can divide on its own, inner membrane will be similar of bacteria
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