Origin of Life Flashcards

1
Q

Origin of Life

A

Began 3.5 -3.9 billion years ago

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2
Q

Miller-Urey Experiment

A

Provided evidence that organic molecules needed for life could be formed from inorganic components

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3
Q

Steps to Life Formation

A

Earth and atmosphere formed

Seas formed

Complex molecules synthesized

Polymers and self replicating molecules synthesized

Organic molecules concentrated and isolated into protobionts

Primitive heterotorphic prokaryotes formed

Primitive autotrophic prokaryotes formed

Oxygen and ozone layer formed, abiotic chemical evolution ended

Eukaryotes formed

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4
Q

Earth and Atmosphere formed

A

Atmosphere formed from volcanic outgassing the molten interior of planet earth

Had a reducing atmosphere

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5
Q

Reducing Atmosphere

A

Early earth contained no O2, but it contained CO, CO2, H2, N2, H2O, S, HCl, and HCN

Cyanobacteria responsible for adding oxygen to atmosphere

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6
Q

Seas Formed

A

Earth cooled down, causing gases to condense, resulting in water and minerals that make up the sease

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7
Q

Complex Molecules Synthesized

A

a.a., acetic acid, formaldehyde formed

Monomers formed

Formation of simple molecules made possible by absence of oxygen (oxygen is very reactive)

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8
Q

Organic soup

A

Inorganic molecules made into organic molecules via energy from UV light, lightning, radioactivity, and heat

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9
Q

Polymer and Self Replicating Molecules

A

Monomers formed polymers via dehydration/condensation reaction

Proteinoids formed

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10
Q

Protenoids

A

Abiotic polypeptides formed by allow a.a. to dehydrate on hot, dry substances

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11
Q

Protobionts

A

Self organized sphere of lipids that provided border where chemical reactions could take place (like a cell)

Precursor of cells

Unable to reproduce

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12
Q

Microspheres and Coacervates

A

Abiotically produce protobionts

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13
Q

Heterotrophic Prokaryotes

A

Can’t make own food
Obtain energy by consuming other substances

i.e. Pathogenic bacteria

Organic soup made from inorganic material was the original source of organic material for these heterotrophs

Natural selection occurred over time for competing cells

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14
Q

Autotroph

A

Heterotrophs mutated and gained the ability to make their ow food (from light or energy from inorganic substances)

i.e. Cyanobacteria (photosynthetic bacteria)

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15
Q

End of Abiotic Chemical Evolution

A

Autotrophs release oxygen as a byproduct

Oxygen reacted with UV formed the ozone

Ozone absorbs UV light, preventing it from reaching the surface of the planet
Prevented abiotic synthesis of organic molecules (UV light was the major source of energy)

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16
Q

Endosymbiotic Theory

A

Eukaryotic cells originated from various prokaryotes who, when together, formed a mutually beneficial association. Therefore, mitochondria, chloroplasts, etc. moved inside a prokaryote to form the eukaryote

17
Q

Evidence for Endosymbiotic Theory in Mitochondria/Chloroplasts

A

Have circular DNA with no proteins like bacteria/cyanobacteria

Ribosomes resemble bacteria and cyanobacteria

Reproduce independently of the eukaryotic cell in a binary fission fashion (like in bacteria)

Double membranes might be from prokaryote surrounding the organelle

Thylakoid membranes similar to photosynthetic membranes in cyanobacteria

18
Q

Evolution of FIsh

A

Jawless fish—-> cartilaginous fish—-> lobe finned fish

19
Q

Evolution of Chordates

A
Notochord 
Head 
Vertebral column
Jaw and mineralized skeleton
Lungs/lung derivatives
Lobed fins
Limbs with digits
Amniotic eggs 
Production of milk
20
Q

Notochord

A

Lanceletes and tunicates

21
Q

Head

A

Hagfish

22
Q

Vertebral Column

A

Jawless fish (Class Agnatha)

23
Q

Jaw

A

Class Chondrichtyes

i.e. sharks

24
Q

Lungs

A

Ray finned fish

Class Osteichthyes

25
Q

Limbs with digits

A

Amphibians

Class Amphibia

26
Q

Amniotic eggs

A

Reptiles (Class Reptilia)

Birds (Class Aves)

27
Q

Production of milk

A

Mammals (Class Mammalia)