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39 Cards in this Set
- Front
- Back
all organisms possess a genetic system based on replication of DNA
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heredity
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supernatural or divine origin
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special creation
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hypothesis that proposes meteors or cosmic dust brought life to earth
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panspermia (extraterrestrial origin
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life originated from inanimate materials
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spontaneous origin
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life most likely emerged under ___ conditions
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high temperature
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the early atmosphere
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reducing atmosphere
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in a reducing atmosphere, the exact conditions are ___.
there was an ample availabilty of ___ but very little ___. |
unknown, hydrogen atoms, oxygen
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ideas of origin
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-the ocean's edge
-under frozen oceans -deep in the earth's crust -within clay -deep-sea vents |
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origin-bubble hypothesis
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ocean's edge
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origin-problematic due to necessary conditions (temperature)
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under frozen oceans
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origin-byproduct of volcanic activity
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deep in earth's crust
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origin-was positively charged so it provided catalytic surface
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within clay
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origin-conditions suitable for Archaea
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deep-sea vents
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attempted to reproduce early reducing atmosphere and produce organic compounds from inorganic materials
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Miller Urey Experiment
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steps of Miller-Urey experiment
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1. assembled reducing atmosphere rich in H and excluding gaseous oxygen
2. placed atmosphere over liquid water 3. maintained mixture at a temp lower than 100C 4. simulated lightning by bombarding it with energy in the form of sparks |
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3 hypotheses of chemical evolution
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RNA, Protein, Peptide-Nucleic Acid worlds
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c. evolution - molecules could not have consistently formed without a mechanism of heredity (replication)
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RNA world
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c. evolution - replication would be impossible without enzymes
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Protein world
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c. evolution - RNA is too unstable, thus a precursor must have existed
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Peptide-nucleic acid world
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certain molecules sontaneously formed bubbles (esp. protein and lipids) that shielded the hydrophobic regions of the molecules from contact with water
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bubble theories
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chemical concentrating, bubblelike structures
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protobiont
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protobionts allowed chemical complexity
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primary abiogenesis
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there is no major agreement on one ___ theory
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bubble
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resemble prokaryotes-lack a nucleus of more complex eukaryotes
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microfossils
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microfossils have been found in rocks as old as ___ yrs
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2.5 billion
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most primitive organisms-extreme condition prokaryotes
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archaebacteria
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archabacteria lack ___ in cell walls (a protein carbohydrate complex)
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peptidoglycan
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archaebacteria that produce methane
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methanogens
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some archaebacteria were ___(salt lovers) or ___(heat lovers)
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halophiles, thermophiles
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archaebacteria are thought to have split from ___ 2 billion years ago
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bacteria
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second major group of prokaryotes (contains most modern proks)
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bacteria
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bacteria has strong ___ and a simpler ___
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cell walls, gene structure
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photosynthetic blue-green algae
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cyanobacteria
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Eukaryotes arose about ___ years ago
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1.5 billion
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internal membrane-bound structures such as mitochondria and chloroplasts are thought to have evolved via ___
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endosymbiosis
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endosymbiosis
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enrgy-producing bacteria were engulfed by larger bacteria which formed a beneficial symbiotic relationship
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eukaryotic cells can ___ which carries out genetic recombination, the key to evolution
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reproduce sexually
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the development of ___ has arisen many times among eukaryotes and fosters specialization
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multicellularity
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some cells devote all energies to one task, other cells to another
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specialization
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