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44 Cards in this Set
- Front
- Back
What did the first life on Earth breathe?
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CO2
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What was the first life on Earth?
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cyanobacteria
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Water and other volatiles came from...
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comet impacts
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Did we have the right elements?
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yes
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blank + blank make amino acids
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these elements plus lightning
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DNA may have originated from these acids in a _______
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clay matrix
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Reproduction occurs via.....
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DNA
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Evolution with a capital
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E
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3 causes of mutation
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1. Radiation (all those rock decays; cosmic rays)
2. Chemical contamination 3. “Transcription errors” |
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Define Senescence
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Biological Aging
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Define Apoptosis
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Programmed Cell Death
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Define Unregulated Cell Division
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leads to a tumor or cancer
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Define natural selection
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those with competitive “edge” more likely to succeed in reproducing; those without are less likely
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examples of natural selection
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1. TB bacteria and antibiotics
2. cockroaches and insecticide 3. light/dark pepper moths in England |
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Requirements for Mutational Evolution
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MANY INDIVIDUALS (AT LEAST ONE QUADRILLION)
SMALL BODY SIZE (LESS THAN TWO CM.) SHORT GESTATION PERIOD (LESS THAN THREE MONTHS) LARGE NUMBER OF PROGENY |
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Hoyle - what did he think?
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the probability of cellular life evolving were about one-in-1040000. He commented: The chance that higher life forms might have emerged in this way is comparable to the chance that a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein.
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Talk to me about Shapiro and Genomes
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not really the static "beads on a string" Rather, they are fluid and complex.now seen as multipurpose elements that turn on and off as required for the survival and well-being of the organism they belong to
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Stromatolites
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Large agglomerations of single-celled organisms
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Stromatolites first form
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microbial mats
(produces layered fossils) |
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Do Stromatolites still exist today?
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yes
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Why at 2.5 GYA did the O2 level jump?
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LOTS of cyanobacteria and other CO2 breathers
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How did this work chemically?
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liberated O2 from CO2
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Prokaryotes
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simple structure, no nucleus
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Endosymbiotic theory
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Idea that complex eukaryotes formed from symbiotic relationship between simpler prokaryotic cells
In other words, big cell “encapsulates” smaller specialized prokaryotes which form mitochondria, chloroplasts, etc. |
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4 examples of evidence of endosymbiotic theory
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1. Mitochondria have their own DNA, which is unlike nuclear DNA but similar to prokaryote DNA
2. Chloroplasts actually resemble cyanobacteria 3. “Main cell” offered nucleus which stores most of the mitochondria/plastid DNA in a more “protected” environment 4.Laboratory observations of endosymbiotic relationships developing between some algaes and prokaryotes |
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Single-Celled Evolution
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Move from cyanobacteria (simple) to green algae (complex)
From prokaryote to eukaryote Eukaryotes have 10x to 1,000x more DNA (information for complex structures) |
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600 MYA
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start seeing a range of multi-cellular organisms
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The Ediacaran Fauna
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Small fossils (typically a few mm to a few cm)
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Cyclomedusa
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common fossil round symetry
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Tribrachidium
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3-fold symmetry
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Spriggina
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bilateral symmetry - shows animal features
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Ediacaran Properties
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All “soft-bodied” – vaguely reminiscent of jellyfish and anemones
For early ones, not sure if the moved around or not – could be “filter feeders” |
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the Burgess Shale
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fossil deposit in Northern Canada
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Trilobites
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found in the Cambrian
Armor Legs Mouth Eyes (!!) |
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The Cambrian Explosion
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only in bodies of water
enabled by sudden massive amount of O2 |
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Permian Period
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Earth would now have been “recognizable
Land has immense forests of trees and other plants (but no flowers!) |
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Pangea
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new supercontinent formed about one every 500 million years
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Permian Extinction (The Great Dying)
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Overall mortality of living creatures even for “survivor” species might have been >95-99%
Fungal spike |
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Why did the Permian Extinction Occur?
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Glaciation of Gondwana
Simultaneous glaciation of the poles Volcanoes Formation of Pangaea |
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Mesozoic
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follows Permian extinction
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Mesozoic period brought us
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angiosperms, and mammals
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The Cretaceous-Tertiary (K-T) extinction
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Alvarez and alvarez came up with the KT theory that a meteor hit and caused dust to come up and kill all life
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Chicxulub
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Evidence of the crater
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Tunguska
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airburst in Russia
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