Ch 16 The Origin of Life Flashcards

1
Q

what is the theory of spontaneous generation

A

The hypothesis that life regularly arises from non-life

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2
Q

how did three scientists disprove spontaneous generation

A
  • Francesco Redi sealed pieces of meat off from the outside to prove that maggots didn’t generate into existence on the meat, but hatched from eggs
  • Lazzaro Spallanzani redid an experiment failed by John Needham that involved gravy and brought a similar result to Francesco Redi
  • Louis Pasture isolated a broth from a year to show the same results
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3
Q

what environment did the first life forms develop in

A
  • About 4 billion years ago, after the earth has cooled it was still a hostile place
  • Eventually the atmosphere formed a mixture of gases, H2O, CO, CO2, H2, N2, and maybe NH3 and CH4, a primordial soup
  • Eventually oceans formed and ~3.5 billion years ago fossil microbes show up, the first record of life
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4
Q

what did Stanley miller and Harold Urey do

A
  • Stanley Miller and Harold Urey experimented by creating a synthetic atmosphere similar to that of early earth and subjected it to energy through sparks to simulate lightening, sun, etcetera
  • Their Experiments produced several biological molecules like urea, lactic acid, and amino acids
  • These experiments show how the building blocks of life can form on early earht
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5
Q

what did Alexander opaline and Sidney fox do

A

The formation of complex molecules would be necessary for life to occur
- Alexander Oparin and Sidney Fox have shown that simple molecules can link together to form complex ones in the absence of oxygen
- Sometimes these molecules gather into droplets that demonstrate some qualities similar to life (though they are not alive)

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6
Q

what are some thoughts on the first organism

A
  • it is still a mystery how life started as it is truly complex
  • One theory is that RNA was the first code used and evolved to produce certain enzymes
  • Life is believed to have started by hydrothermal vents
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7
Q

what were the first true cells like

A
  • Prokaryotic
  • Heterotrophic
  • Anaerobic
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8
Q

why and how did photosynthesis evolve

A
  • As certain complex molecules were depleted organisms would need a way to synthesize them from similar ones
  • For this, outside energy would be very helpful
  • early photosynthesis eventually evolved, though were very different and probably used H2S instead of H2O, and were very successful
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9
Q

why can’t life begin again on earth

A

Life cannot arise again as the presence of oxygen and bacteria would prevent the required molecules from forming

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10
Q

what happened around 2.2 billion yrs ago

A
  • around 2.2 billion years ago, photosynthesis using H2O evolved, they produced O2 into the air
  • O2 was initially very deadly to organism
  • O2 eventually reformed into O3 at the upper atmosphere making the ozone layer protecting the earth from the sun
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11
Q

how did aerobic metabolism evolve

A
  • Eventually organism adapted to use O2 in their metabolism
  • This made them way more effective in acquiring energy from sugars
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12
Q

when did eukaryotes evolve

A
  • happened around 1.4-1.6 billion years ago
  • organelles formed
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13
Q

what did the evolution of sexual reproduction do

A
  • increased the speed of evolution
  • asexual reproduction leads to clones with little variation
  • sexual reproduction shuffles genes between the parents
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14
Q

when did the first multicellular organisms evolve

A

a few million years after sexual reproduction evolved, the first multicellular organisms arose

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