test 2: abiogenesis and natural selection Flashcards
the hadean (first geological eon)
- life originated under very different conditions
- atmosphere of early earth may have been a reducing atmosphere thick water vapor, nitrogen and its oxides, carbon dioxide, methane, ammonia, hydrogen and hydrogen sulfate (changes examined through ice/permafrost)
abiogenesis (chemosynthetic origin of life)
- conditions of early planet were very different from today
- gases like nitrogen, methan and hydrogen sulfide
- 1920s: oparin and haldane hypothesized that early oceans were a chemical soup
oparin and haldane
- independently hypothesized:
1. earth’s early atmosphere was a reducing (electron-adding) environment in which organic molecules could have formed
2. energy for this organic synthesis could have come from lightning and intense UV radiation
life arose from a “primordial soup”
miller and urey
- tested oparin and haldane’s theory
- using atmosphere thought to exist during early Earth
- under extreme heat situations, researchers have been able to create polymers without the help of enzymes
- WW2 and submarines allowed them to test in deep sea conditions
protobionts
- collections of abiotically produced molecules surrounded by a vesicle-like structure (rudimentary cell)
- replication may have originally have been through RNA; occasionally a copy error would occur and protein becomes more stable (better for selection)
- DNA more stable than RNA and less copy errors
synthesis of polymers
- lab simulations of early earth conditions produced organic polymers
- polymers made by dripping solutions of monomers onto hot sand, clay or rock
- nucleotides + hot sand/clay/rock = RNA
- everything started as RNA, became DNA because it was more stable
4 main stages to creating simple cells:
1 - abiotic synthesis of small organic molecules
2 - joining small molecules into macromolecules (ex: proteins)
3 - packaging protobionts with membranes capable of isolating an internal environment
4 - origin of self-replicating molecules; first RNA then DNA; eventually photoautotrophs became prominent (CO2 –> O2; leads to atmosphere)
self-replicating RNA came first
- first genetic material
- could catalyze protein formation
- molecules are flexible, single stranded and can assume a variety of shapes
ribozymes
RNA enzymes can make copies of RNA, provided they are supplied with monomers
evolution of eukaryotes
- endosymbiosis (mitochondria and chloroplasts were prokaryotes)
- entry gained as undigested prey or internal parasites
- anaerobic endosymbionts greatly favoured
evidence of endosymbiosis
- inner membrane have same transport mechanisms and enzymes as prokaryotes
- replicate by a splitting process
- have their own DNA and ribosomes, replicate independently of other DNA
early ideas of evolution
- philosophers had idea that evolution might exist
- book of genesis: judeo-christian culture took over
ie: creationists dogma, other cultures believed in some form of evolution
evidence began to accumulate (fought by church)
Carolus Linnaeus
- classify life’s diversity “greater glory of God”
- founder of taxonomy
- developed two part binomial format for naming species
Georges Cuvier
- studied fossils extensively
- idea of old fossils at bottom, newer ones on top
- idea of extinctions being a common occurrence throughout history
- opposed idea of evolution, advocated idea of catastrophism
catastrophism
Cuvier’s idea that boundaries between strata were due to local floods or droughts destroying present species
james hutton
father of geology, came up with ideas about the continents (earth’s geological features explained by gradual mechanisms still operating); established geological assessment (continental plate shifting)
lyell
- personal friend of darwin, uniformitarianism
- changes in earth’s surface result from slow continuous actions still operating today
- changes so slowly that change isn’t seen in one lifetime
lamarck
- first theories of evolution but incomplete
- use and disuses during the animals lifetime
- changes passed on to next generation
- recognized that environments can influence organisms and give rise to evolution
- “didn’t use it, lose it” –> during one generation
malthus
- principle of population essay
- human population increasing so fast that we will run out of food, and wars would start
- “don’t support the poor, will only breed more poor” - very unpopular, kinda an asshole
darwin
- interested in nature
- dropped out of med school
- degree in theology from Cambridge
- voyage on beagle as a naturalist, captured/observed/collected specimens (captain had connection with Lyell)
beagle voyage
- temperate areas of south america: species distinctly south American, not like in Europe
- found ocean fossils in andes after earthquake
- galapagos finches
- “descent with modification”
origin of species
- published by darwin
- wallace had a similar idea of evolution, wrote an essay, sent it to darwin
- both works presented by Lyell at society meeting
- most credit goes to Darwin (more complete idea of evolution)
darwin-wallace theory of evolution
1- variation in the individuals of a population
2- variations are inherited
3- members of a pop will always produce more offspring than environment can support
4- survival of the fittest; individuals with more advantageous characteristics leave more offspring
what were darwin and wallace missing?
- didn’t know about DNA
- didn’t know about mitosis/meiosis
