Chp 22 Flashcards

1
Q

The universe began with the Big Bang about how many years ago

A

13.7 bya

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2
Q

H and He were converted to what heavier elements

A

C, N, O

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3
Q

Stars that exploded are called

A

Supernovas

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4
Q

Clouds collapsed to make

A

New stars and soar systems

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5
Q

Solar systems began

A

4.6 bya

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6
Q

Earth is how old

A

4.55 bya

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7
Q

Earth originated from aggregation of

A

Planetesimals over a period of 100-200 my

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8
Q

Earth cooled enough for outer layers to solidify and oceans to form

A

4 bya

Four cooling

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9
Q

Origin in 4 overlapping stages

A

Nucleotides and AA—>[polymerize] DNA, RNA, and proteins —>[enclosed in] membrane —>[aquired] cellular properties

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10
Q

Organic molecules

A

Little free oxygen gas

Prebiotic soup

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11
Q

Reducing atmosphere hypothesis

A

Atmosphere rich in water vapor, h2, ch4, nh3 and little o2
Miller- urey experiment of 1953
Formed precursors, AA, sugars and nitrogenous bases
Showed says techsis was possible not proven

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12
Q

Extraterrestrial hypothesis

A

Meteorites brought organic carbon to earth; may include amino acids and Nucleic acid bases
Opponents argue that most of this would be destroyed in the intense heating and collision

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13
Q

Deep sea vent

A

Molecules may have formed in the temp gradient between extremely hot vent water and cold ocean water
Supported by experiments (kirt: the only experiments were those that show fe reacts with h2s to form pyrites and give off energy that may cause n2 to form nh3
Communities that derive energy from chemicals in the vent found here

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14
Q

Prebiotic synthesis if polymers not possible in aqueous solutions because

A

Hydrolysis competes

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15
Q

Formation of Nucleic acid polymers and polypeptides on what kind of surface

A

Clay because they can bind organic molecules because of negative charges, and they attract metal ions like Mg+ that can catalyze rxns to produce polymers

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16
Q

Their experiments they added monomer building blocks and watched them aggregate

A

They positioned the nucleotides

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17
Q

Aggregate of prebiotically produced molecules and macromolecules that aquired a boundary

A

Protobiont

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18
Q

Boundary that allowed it to maintain an internal chemical environment distinct from that of its surroundings

A

Lipid bilayer

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19
Q

4 characteristics of protobionts

A
  1. Boundary Seperated external environment from internal contents
  2. Polymers inside the protobiont contained information
  3. Polymers inside the protobiont had enzymatic function
  4. Protobiont capable of self replication-not self reproduction but divide to increase in number
    Assumption that metabolic pathways formed w/in that could modify the molecules.
20
Q

Droplets that form spontaneously from the association of charged polymers

A

Coacervates

Enzymes inside can perform primitive metabolic function

21
Q

Vesicles surrounded by a lipid layer

A

Liposomes

22
Q

Clay can catalyze for action of ___ that grow and divide

A

Liposomes

23
Q

Majority of scientists favor ___ as the first macromolecules of protobionts

A

RNA –simpler

24
Q

3 key RNA functions

A
  1. Ability to store information
  2. Capacity for self replication
  3. Enzymatic functions-ribozymes
25
Q

DNA and proteins do not have all 3 functions

A

True

26
Q

Chemical within a mixture of different chemicals has special properties or advantages that cause it to increase in number compared to other chemicals in the mixture

A

Chemical selection

27
Q

Hypothetical scenario with 2 steps

A
  1. One of the RNA molecules mutates and has enzymatic ability to attach nucleotides together- advan of faster replication
  2. Second mutation produces enzymes ability to synthesize nucleotides - no reliance on prebiotic synthesis
28
Q

Information storage

A

DNA would have relieved RNA of informational role and allowed RNA to do other functions

DNA is less likely to suffer mutations or breaks

29
Q

Metabolism and other cellular functions

A

Proteins have a greater catalytic potential/efficiency

Proteins can perform other tasks-cytoskeleton, transport, etc

Proteins came into being as RNA can catalyze formation of peptide bonds

30
Q

Preserved remains of past life on earth

A

Fossils

31
Q

Who study fossils

A

Paleontologists

32
Q

Many rocks with fossils are

A

Sedimentary

33
Q

Older rock is deeper and older organisms are ___ in the rock bed

A

Deeper

34
Q

Fossils can be dated using elemental isotopes in accompanying rock

A

Radioisotope dating

35
Q

Length if time required for exactly one half of the original isotope to decay
measures amount of a given isotope as well as the amount of the decay product
usually igneous rock dated

A

Half life

36
Q

Geological time scale: origin 4.55 bya to present

The four eons are:

A

Hadean 4.5-3.8 bya - 3.8- first prokaryo
Archaean 3.8-2.5 bya- 2.5 first eukaryo
Proterozoic 2.5 to 543 mya- Cambrian explosion
Phanerozoic- 543 mya to present

37
Q

Changes in living organisms the result of

A

genetic changes

38
Q

Environment changes:

A

allow for new types of organisms

responsible for extinctions

39
Q

Major environmental changes

A
climate temp
atomosphere (o2 started accum 2.4 bya)-  origin of body plans coincide with o2 rise
land masses-continental drift occured
flood
glaciation snowball earth hyopthesis
volcanic eruptions
meteoric impacts
40
Q

Mass extinctions- 5 large mass extinctions

A

near end of Ordovician, Devonian, Permian, Triassic, and Cretaceous periods
boundaries between geoloci time periods are often based on these events

41
Q

rapid extinction of mmany modern species due to human activites is sometimes referred to as the

A

sixth mass extinction

42
Q

When diverse microbial life (prokaryotic cells) floursihed in primoridal oceans

A

archaeon eon

43
Q

all life forms prokaryotic during
hardly any free oxygen so organisms were anaerobic
first cells were heterotrophs; autotropsh evolved as supply of organic molecules dwindled

A

Archaeon Eon

44
Q

layered structure of calcium carbonate

A

stromatolites

45
Q

Multiccellular eukary arise 1.5 bya; 2 possible origins
indiv form a colony
single cell divides and stays stuck together
First animals invertebrates-bilateral symmetry facilitates locomtion

A

proterozoic eon

46
Q

Paleozoic era- cambria, ordovician, silurian, devonian, carboniferous, permian
Mesozoic era- triassic and jurassic
Cenozoic era- tertiary and quaternary

A

Phanerozoic Eon- proliferation of multicellular eukaryotic life extensive