Chapter 18: Origin and History of Life Flashcards by Gail I

all life on earth can be traced back to a single ancestor → …: …

LUCA: last universal common ancestor

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LUCA common to all organisms that have

lived or live on Earth

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According to Darwin, first life form came about in a … with …, …, .., …, …, etc

warm little pond; ammonia; phosphoric salts; light; heat; electricity

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biomolecules: the molecules of … → …

living things; organic molecules

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life originated from nonliving matter in

4 stages

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(4 stages) stage 1: …., simple … evolved from … before cells came to be: e.g. .. and …

organic monomers; monomers; inorganic compounds; amino acids; nucleotides

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(4 stages) stage 2: …, organic monomers … to form …: e.g. …, …, and …

organic polymers; polymerized; organic polymers; DNA; RNA; proteins

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(4 stages) stage 3: …, organic polymers became …, forming the … (…/…)

protocells; enclosed in a membrane; cell precursors; protocells; probionts

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(4 stages) stage 4: …, probionts acquired ability to …, among other …

living cells; self-replicate; cellular properties

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abiogenesis: origin of … from ..

.life; nonliving matter

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(stage 1. evolution of monomers) oparin-haldane hypothesis → … hypothesis

primordial soup

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(stage 1. evolution of monomers) oparin-haldane: first stage in the origin of life was … from … present in Earth’s ….

evolution of monomers; inorganic compounds; early atmosphere

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(stage 1. evolution of monomers) early earth had very little …, made up of …, …, …, …

oxygen; water vapor; hydrogen gas; methane; ammonia

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(stage 1. evolution of monomers) methane and ammonia are …, powerful when ….

reducing agents; oxygen is absent

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(stage 1. evolution of monomers) oparin-haldane: early earth had …. in which .. reactions could have driven … (…) of organic monomers from inorganic molecules with addition of …

reducing atmosphere (because of CH4 and NH3); redox; chemical evolution; abiotic synthesis; energy

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(stage 1. evolution of monomers) miller-urey experiment: early earth energy sources: heat from … and …, … from isotopes, … in …, … (particularly …)

volcanoes; meteorites; radioactivity; electric discharges; lightning; solar radiation; ultraviolet

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(stage 1. evolution of monomers) miller-urey experiment: miller placed mixture of …, …, …, and … in a closed system and … it, and also circulated it past an …

methane; ammonia; hydrogen; water; heated; electric spark

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(stage 1. evolution of monomers) miller-urey experiment: variety of … and other … were formed
- all …

amino acids; organic acids; 22 amino acids

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(stage 1. evolution of monomers) miller-urey experiment: recent evidence suggests that … and … would have been abundant in early Earth atmosphere, challenging validity of experiment
BUT: other experiments showed that ammonia could have been produced when ….

nitrogen gas; ammonia; iron-nickel sulfides catalyzed change of N2 to NH3

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(stage 1. evolution of monomers) miller-urey experiment: small organic compounds formed on surface by atmospheric gases would not have been destroyed through … or …, as there was no … or …, and … would have washed them into the … where the … could become …

oxidation; decay; free oxygen; bacteria; ocean; oceans; warm organic soups

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(stage 1. evolution of monomers) iron-sulfur world hypothesis: proposal that thermal vents at the bottom of oceans could have provided all the … and … necessary to …

elements; conditions; synthesize organic monomers

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(stage 1. evolution of monomers) iron-sulfur world hypothesis: … emitted from vents (…., …, …) pass over … and … minerals, which would then act as … that drive chemical evolution from …. to … molecules

dissolved gases; carbon monoxide; ammonia; hydrogen sulfide; iron; nickel; catalysts; inorganic; organic molecules

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(stage 1. evolution of monomers) extraterrestrial origins hypothesis: organic molecules from … and … could have .. the chemical origin of life on earth

comets; meteorites; seeded

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(stage 1. evolution of monomers) extraterrestrial: some hypothesize that … evolved first on another planet

bacterium-like cells

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(stage 2. evolution of polymers) in cytoplasm, organic monomers join to form ... in the presence of ...

polymers; enzymes

(stage 2. evolution of polymers) enzymes are

proteins

(stage 2. evolution of polymers) iron-sulfur world hypothesis: organic molecules will .... and amino acids will form ... in presence of .... under conditions found at ...

react; peptides; iron-nickel sulfides; thermal vents

(stage 2. evolution of polymers) iron-sulfur world hypothesis: iron-nickel sulfides have a ... that attracts ... and .... to form ...

charged surface; amino acids; binds them together; proteins

(stage 2. evolution of polymers) protein-first hypothesis: amino acids polymerize abiotically when exposed to

dry heat

(stage 2. evolution of polymers) protein-first hypothesis: once amino acid were present in oceans, they could have collected in ... along ...

shallow puddles; rocky shore

(stage 2. evolution of polymers) protein-first hypothesis: heat of the sun could cause amino acids to form ..., small.... with some ...

proteinoids; polypeptides; catalytic properties

(stage 2. evolution of polymers) protein-first hypothesis: in water, proteinoids form ..., structures composed only of ... that have many ....

microspheres; protein; cell properties

(stage 2. evolution of polymers) protein-first hypothesis: newly formed polypeptides may have had ..., a selectively .... trait → .... in formation of first cell

enzymatic properties; advantageous; natural selection

(stage 2. evolution of polymers) protein-first hypothesis: assumes that protein enzymes arose prior to ...: genes that encode proteins followed evolution of ...

first DNA molecule; first polypeptide

(stage 2. evolution of polymers) RNA-first hypothesis: suggests that only ... was needed to progress toward formation of cell

RNA

(stage 2. evolution of polymers) RNA-first hypothesis: RNA can be both a ... and ...

substrate; enzyme

(stage 2. evolution of polymers) RNA-first hypothesis: some viruses have

RNA

(stage 2. evolution of polymers) RNA-first hypothesis: RNA could have carried out processes of life commonly associated with ... and ...

DNA; proteins

(stage 3. evolution of protocells) protocell/probiont: structure characterized by having an

outer membrane

(stage 3. evolution of protocells) life requires chemical reactions to take place within a ... to protect from ...

boundary; disruption of conditions

(stage 3. evolution of protocells) cell's plasma membrane is critical to ... and ... of ...

regulation; maintenance; cellular activities

(stage 3. evolution of protocells) modern cell membrane made up of ... in a ..., where first plasma membranes were likely made of ....

phospholipids; bilayer; fatty acids

(stage 3. evolution of protocells) fatty acids could have formed from

chemical reactions at hydrothermal vents

(stage 3. evolution of protocells) in water, fatty acids assemble into small spheres called ... → single layer of ... organized with ... pointed out and ... pointed toward sphere's center

micelles; fatty acids; hydrophilic heads; hydrophobic tails

(stage 3. evolution of protocells) micelles can merge to form ....

vesicles

(stage 3. evolution of protocells) vesicles are ... than micelles and are surrounded by a .... of ....

larger; bilayer; fatty acids

(stage 3. evolution of protocells) individual fatty acids can flip between ..., to help move select molecules ....

two layers; into or out of the cell

(stage 3. evolution of protocells) first protocell likely this sort of

vesicle

(stage 3. evolution of protocells) if ... are made available to protein microspheres, they can associate and form a ...

lipids; lipid-protein membrane

(stage 3. evolution of protocells) shared properties with modern cells: resemble ..., .... difference, ..., subject to ...

bacteria; electrical potential; divide; selection

(stage 3. evolution of protocells) oparin showed that under certain ..., ..., and ... conditions, mixtures of macromolecules can form ...., which tend to ... and incorporate substances from ...; eventually, a ... could form

temperature; ionic composition; pH; coacervate droplets; absorb; environment; semipermeable boundary

(stage 3. evolution of protocells) bangham discovered that lipids could naturally organize themselves into ... about the size of a ... → ...

double-layered bubbles; cell; liposomes

(stage 3. evolution of protocells) liposomes could have provided life's first

membranous boundary

(stage 3. evolution of protocells) maybe liposomes with phospholipid membrane engulfed other early molecules with ..., or ... abilities

enzymatic; replicative

(stage 3. evolution of protocells) membrane-first hypothesis: first cell had to have a ... before any other parts

plasma membrane

(stage 3. evolution of protocells) a protocell would need .... (....) so that it could ...

nutrition; other molecules; grow

(stage 3. evolution of protocells) hypothesis that protocells were ...: organisms that consume ...

heterotrophic; preformed organic molecules

(stage 3. evolution of protocells) if protocells evolved at hydrothermal vents, they could have carried out ....: synthesis of ... from ... and ...

chemosynthesis; organic molecules; inorganic molecules; nutrients

(stage 3. evolution of protocells) glycolysis: metabolic pathway that transforms ... into ... for a cell to do ...

high-energy chemical bonds; energy; work

(stage 3. evolution of protocells) glycolysis: first stage of ..., occurs otuside of ...

cellular respiration; mitochondria

(stage 3. evolution of protocells) glycolysis: in early stages of life's origin, ATP would have been available in a ... as an energy source

preformed state

(stage 3. evolution of protocells) natural selection would have favored evolution of .... as means to provide renewable energy supply

ATP/ADP recycling

(stage 3. evolution of protocells) natural selection of ATP/ADP must have occurred very .... in history of life, since all life on Earth uses ATP

early

(stage 3. evolution of protocells) ATP likely synthesized first by

fermentation

(stage 3. evolution of protocells) mitochondria share common ancestor with group of ... that ... via an ...

bacteria; synthesize ATP; electron transport chain

(stage 3. evolution of protocells) protocell must have first had limited ability to ..., millions of years for ... to completely evolve

break down organic molecules; glycolysis

(stage 3. evolution of protocells) some evidence suggests that microspheres from which protocells evolved may have had some

catalytic ability

(stage 4. Evolution of a Self-Replication System) central dogma:

DNA → RNA → protein

(stage 4. Evolution of a Self-Replication System) according to RNA-first hypothesis: RNA first to

evolve

(stage 4. Evolution of a Self-Replication System) according to RNA-first hypothesis: these genes would have directed and enzymatically conducted

protein synthesis

(stage 4. Evolution of a Self-Replication System) evidence for RNA-first thing: ribozymes are ..., viruses have ...

enzymatic RNA molecules; RNA genes

(stage 4. Evolution of a Self-Replication System) RNA-first hypothesis: reverse transcription may have occurred within protocell, eventually leading to ..., once DNA genes developed, protein synthesis would occur according to ...

DNA-encoded genes; central dogma

(stage 4. Evolution of a Self-Replication System) according to protein-first hypothesis: ..../... were first

proteins; polypeptides

(stage 4. Evolution of a Self-Replication System) protein-first: after protocell developed a plasma membrane and enzymes, it had ability to synthesize ... and ... from ... in ...

DNA; RNA; small molecules; ocean

(stage 4. Evolution of a Self-Replication System) protein-first: Because nucleic acids are complicated, it seems more likely that ... were needed first to guide synthesis of ... and then ....

enzymes; nucleotides; nucleic acids

(stage 4. Evolution of a Self-Replication System) after DNA formed, protein synthesis would occur according to

central dogma

(stage 4. Evolution of a Self-Replication System) Cairns-Smith proposed that polypeptides and RNA evolved at the ..., such that first true cell would have ... that could replicate because of presence of ..., this means, though, that two unlikely events would happen at same time

same time; RNA genes; proteins

Chapter 18: Origin and History of Life Flashcards

(77 cards)