Lesson 1 - Early Earth and the Diversification of Life Flashcards
1
Q
when was earth formed based on the analysis of slowly decaying radioisotopes?
A
~ 4.5 BYA
2
Q
Earth formed ~4.5 BYA is based on the analysis of?
A
slowly decaying radioisotopes
3
Q
why earth was formed?
A
as a result of nuclear fusions on the sun
4
Q
the sun was formed from what event
A
supernova event
5
Q
what is supernova event
A
the colossal explosion of a star
6
Q
what was formed after the earth cooled over time?
A
metallic core
rocky mantle
lower-density
thin surface crust
7
Q
Early Earth was ____
A
inhospitable
8
Q
Early earth was characterized by what
A
- molten surface under intense bombardment by asteroids and other objects from space, which was thought to have persisted for over 500 M years
9
Q
the intense heat and the absence of liquid water indicate that early earth was certainly a “___”
A
sterile planet
10
Q
indicated that early earth was a “sterile planet”
A
intense heat
absence of liquid water
11
Q
indicate the presence of solid crust and liquid water on the earth as early as 4.3 BYA
A
Analyses of ancient zircon crystals
12
Q
what did the analyses of ancient zircon crystals indicate about the earth
A
the presence of :
1. solid crust
2. liquid water on earth as early as 4.3 bya
13
Q
suggest biogenic origin, providing evidence for life on Earth 4.1 BYA
A
further evidence based on carbon isotope ratios of graphite materials in zircon minerals
14
Q
What do carbon isotope ratios in graphite materials suggest?
A
biogenic origin, providing evidence for life on earth 4.5 BYA
15
Q
oldest known sedimentary rocks
A
date to 3.86 BYA
16
Q
the most widely used photograph of Earth, taken by the Apollo 17 mission in 1972
A
The Blue Marble
17
Q
What do the oldest known sedimentary rocks indicate?
A
They indicate that oceans were present when the rocks were formed.
18
Q
What do the oldest known sedimentary rocks contain?
A
fossilized remains of what appear to be cells and carbon with isotopic ratios
19
Q
isotopic ratios in the carbon found in the oldest sedimentary rocks provide further evidence for what
A
ancient microbial life
20
Q
- it is a bacteria from 3.45-billion
year-old rocks of the Barberton Greenstone Belt, South Africa. - rod-shaped bacteria (arrow) attached to particles of mineral matter.
- The cells are about 0.7 μm in diameter.
A
microfossil bacteria
21
Q
three oldest facts
A
oldest known Earth minerals (4.4 BYA)
oldest known rocks on earth (4.1 BYA)
oldest known meteorites (4.6 BYA, for the age of the solar system)
22
Q
If life developed from non-living matter then 4 requirements need to be fulfilled on the conditions
of the early earth:
A
- little or no free oxygen
- abundant energy source: to build
biological molecules . - occurrence of chemical building blocks, dissolved inorganic minerals
- time: for molecules to react with one another.
23
Q
- break bonds
- oxidizes, so it is not conductive to biulding molecules
A
O2
24
Q
Where is energy derived
A
violent thunderstorms,
volcanic activity, meteorite bombardment,
intense radiation (lots of UV; no ozone layer
25
atmospheric gases in early earth can be found on meteorite
CO2,
H2O vapor, CO, H2 and N2
26
small amounts of gases in early earth
NH3, H2S, and CH4 (no O2)
27
estimated earth
4.6 bya
28
evidence that life arose on earth
~3.5 bya
29
3 Attempts to reconstruct the early Earth’s atmosphere and chemical profile have led to production of
organic molecules from simpler materials, in the presence of some form of energy
1. In the 1920s , Oparin and Haldane independently proposed that organic molecules could form spontaneously from simpler raw materials when sufficient energy is supplied in a reducing (energy-rich, electron-adding) environment
2. In the 1950s , Miller and Urey created a “reducing atmosphere” of H2O, H2, NH3, CH4 in a spark chamber; after sparking, they found that amino acids and other organic compounds had formed
3. organic polymers can form spontaneously from monomer building blocks on some sand, clay, or rock surfaces
30
designed to mimic what was thought at the time to have been Earth’s early atmosphere
reducing atmosphere
31
later experiments with different “reducing atmospheres” that were thought to be better matches to the likely
atmosphere of the early Earth produced what
all 20 amino acids used in proteins, various sugars and lipids, and components
of DNA and RNA nucleotids
32
current models of the Earth’s early atmosphere are that in general the atmosphere was not
reducing
33
local environments that were reducing
near volcanic activity
34
6 models for how and where life started
1. prebiotic broth hypothesis
2. bubble hypothesis
3. iron- sulfur world hypothesis
4. deep-hot biosphere hypothesis
5. exogenesis
6. religious/Christian belief
35
life began from an organic soup" in the oceans
prebiotic broth hypothesis
36
a variation on the prebiotic broth, with “oily bubbles” from an organic soup interacting with land surfaces at shallow seas or seashores
bubble hypothesis
37
– life began from an “organic soup” interacting with mineral surfaces
at hydrothermal vents in the ocean floor, with abundant iron and sulfur there impacting the early
metabolism that developed
iron-sulfur world hypothesis
38
hypothesized transitions from prebiotic chemistry to
cellular life depicted
model interior of a hydrothermal mound
39
mixes with cooler, more oxidized ocean water,
Hot, mineral-rich hydrothermal
fluid
40
Hot, mineral-rich hydrothermal
fluid mixes with cooler, more oxidized ocean water,
forms?
precipitates of Fe and S compounds, clays,
silicates, and carbonates.
41
what did the mineral precipitates formed that could have served as energy-rich
compartments
pores
42
Mineral precipitates form
pores that could have served as?
energy-rich
compartments that facilitated the evolution of
precellular forms of life
43
– life began in an “organic soup” deep within the Earth
deep-hot biosphere hypothesis
44
– earth was seeded with life from an extraterrestrial source
exogenesis
45
– life was created by a Divine Creator
religious/Christian belief
46
A model for how the first cells could have originated and functioned suggests:
1. Protobionts that resemble living cells , the evolutionary precursor of prokaryotic cells
2. Genetic reproduction was crucial in the origin of true cells
47
- a type of protobiont, that form spontaneously when liquid water is added to abiotically produced polypeptides
- can grow, divide, and maintain internal chemistry different from their surroundings
- show that some spontaneous production and maintenance of organization is possible, but
are incomplete as a model for formation of the first cells
microspheres
48
microspheres can:
grow, divide, and maintain internal chemistry different from their surroundings
49
what does microspheres show
some spontaneous production and maintenance of organization is possible, but are incomplete as a model for formation of the first cells
50
-RNA can catalyze a variety of reactions, including some self-catalytic reactions
-RNA can also store genetic information
-in vitro evolution of RNA has shown that the RNA world hypothesis is feasible – selection can act on self-replicating RNA molecules in vitro
RNA likely was first (RNA world hypothesis)
51
What can RNA catalyze
variety of reactions, including some self-catalytic reactions
52
what can RNA store?
genetic information
53
has shown that the RNA world hypothesis is feasible – selection can act on
self-replicating RNA molecules in vitro
in vitro evolution of RNA
54
what does in vitro evolution of RNA show
shows that the RNA world hypothesis is feasible – selection can act on self-replicating RNA molecules in vitro
55
likely came later and had the selective advantage of greater stability
DNA
56
- is a component of certain essential cofactors and molecules found in all cells (such as ATP,
NADH, and coenzyme A)
- can bind small molecules (such as ATP, other nucleotides, and amino acids);
- it can possess catalytic activity;
- it is known to catalyze protein synthesis through the activities of rRNA, tRNA, and mRNA
RNA
57
possible to imagine that certain RNA molecules once had the ability to
catalyze their own
synthesis
58
these earliest forms of life may have had little or no need for
DNA or protein
59
Events hypothesized to precede the origin of cellular life
prebiotic chemistry -> precellular life -> early cellular life ->LUCA -> Evolutionary diversification
60
prebiotic chemistry
Biological building blocks:
- Amino acids
- Nucleosides
-Sugars
61
Precellular life
1. RNA world:
- Catalytic RNA
- Self- replicating
2. Protein synthesis
-RNA-templated translation
3. DNA
- Replication
- Transcription
62
early cellular life
lipid bilayers:
- cellular compartments
- early cells likely had high rates of HGT
63
LUCA and Evolutionary diversification
divergence of bacteria and archaea:
- components of DNA replication, transcription, and translation all in place
64
Prebiotic -> precellular life -> early cellular life (years)
4.3-3.8 bya
65
LUCA -> Evolution diversification (year)
3.8-3.7 bya
66
earliest self-replicating biological systems may have been based on
catalytic RNA
67
At some point
RNA enzymes evolved the capability to
synthesize proteins
68
became the main catalytic
molecules.
Proteins
69
Conversion from RNA- to DNA-based genomes required what
evolution of DNA and RNA
polymerases
70
the site of electron transport
lipid bilayer
71
evolution of lipid bilayer was important for?
energy conservation, in addition to containing and protecting biomolecules.
72
- preceded the divergence of Bacteria and Archaea
- a cellular organism that had a lipid bilayer and used DNA, RNA, and protein.
last universal common ancestor (LUCA)
73
last universal common ancestor (LUCA) had and used what
had a lipid bilayer and used DNA, RNA, and protein.
74
may have allowed rapid transfer of beneficial genes among early
forms of life
Horizontal gene transfer (HGT)
75
“The earliest cellular forms of life likely possessed
elements of this three-part system of ___,___,___ in addition to a _____ ____ capable of conserving energy."
DNA, RNA, and protein
membrane system
76
Formation of pyrite (FeS2) leads to production of what
H2
77
Formation of pyrite (FeS2) leads to reduction of?
S^o reduction
78
its formation leads to H2 production and S^o reduction
Formation of pyrite (FeS2)
79
fuels a primitive ATPase.
H2 production and S^o
reduction
80
plays only a catalytic role
H2s
81
net substrate of energy-conserving
scheme for primitive cells.
FeS and S^o
82
a possible energy-conserving
scheme for primitive cells required what
few different proteins
83
a possible energy-conserving
scheme for primitive cells reaction
FeS + H2S → FeS2 + H2.
84
a possible energy-conserving
scheme for primitive cells free energy
= -42kJ
85
the first evidence of life in the fossil record
isotopic carbon “fingerprints” in rocks from ~3.8 bya
86
the first evidence of cells
microfossils of prokaryotic cells in fossils of stromatolites
dated to ~3.5 bya
87
rocklike structures made up of layers of bacteria and sediment
stromatolites
88
stromatolites are made up of layers?
bacteria and sediment
89
in some areas,they are still being formed today
stromatolites
90
the first cells were most likely what
anaerobic heterotrophs
91
two reasons why the first cells were most likely anaerobic heterotrophs
1. there was likely an abundance of organic molecules available for food early on
2. later, as organic molecules became scarcer, photosynthetic organisms were favored
92
the first photosynthetic organisms
purple and green sulfur bacteria
93
what does purple and green sulfur bacteria use as hydrogen donor
H2S
94
❑the energy-generating metabolism of primitive cells would have been
EXCLUSIVELY ANAEROBIC
95
during the anerobic energy-generating metabolism of primitive cells,what may have been the major source of carbon for cells (autotrophy)
Co2
96
the process of making food from inorganic substances, using photosynthesis.
autotrophy
97
why a CO2 may have been the major source of carbon for cells
because abiotic sources of organic carbon would quickly have become limiting as life
became more and more abundant on Earth.
98
would have become limiting on the early earth
abiotic sources of fixed nitrogen
99
microbes evolved the ability to use what as source of nitrogen (nitrogen fixation), as early as 3.2 BYA
atmospheric N2
100
the biological or industrial process that converts atmospheric nitrogen (N2) into reactive forms like ammonia (NH3)
nitrogen fixation
101
indicated that microbes
evolved the ability to use atmospheric N2 as a source of nitrogen (nitrogen fixation) as early as 3.2 billion years ago
isotopic ratios of nitrogen found in ancient
sedimentary rocks
102
was a major
fuel for energy metabolism of early cells.
H2
103
hypothesis supported by the tree of life
H2 was a major
fuel for energy metabolism of early cells.
104
Tree of life support the hypothesis, in that virtually all of the
earliest branching organisms in the
___ and ____ use H2 as an
electron donor in energy metabolism and
are also autotrophs
Bacteria and archaea
105
may have been one
of the earliest electron acceptors
Elemental sulfur (S0)
106
why elemental sulfur (S0) may have been one of the earliest electron acceptors
reduction of S0 to yield H2S is exergonic and would likely have required relatively few enzymes
107
because of their abundance on early earth, this scheme would
have provided cells with a nearly limitless supply of energy
H2 and sulfur compounds
108
what did the other early micrrorganism may have used to produce acetate or methane
H2 and CO2
109
Other early microorganisms may have used H2 and CO2 to produce
acetate and methane
110
driven by H2 and would likely have
supported the production of large amounts of organic compounds from autotrophic CO2
fixation.
chemolithotrophic metabolism
111
chemolithotrophic metabolism driven by H2 and would likely have
supported the production of large amounts of organic compounds from
autotrophic CO2
fixation.
112
a heavy sounding term for non
photosynthetic cells/organisms that do not use oxygen as terminal electron acceptor in respiration
anaerobic heterotrophs
113
H2 is used by purple and green sulfur bacteria as electron donor for what
CO2 fixation and generating elemental sulfur (S0) as a waste product
114
The oldest known stromatolite, found in a rock about
3.5 billion years old from the
Warrawoona Group in
Western Australia.
115
How are Stromatolites, or “layered rocks,” are formed
when certain kinds of microbial
mats cause the deposition of carbonate or silicate minerals that promote fossilization
116
Modern stromatolites composed of
thermophilic
cyanobacteria growing in a thermal pool in
Yellowstone National Park, USA.
117
largely gone from Earth today,
but modern examples of this ancient microbial
ecosystem can still be found in certain shallow
marine basins or in hot springs
stromatolites
118
where are stromatolites found in earth today
certain shallow
marine basins or in hot springs
119
The ability to use solar radiation as an energy source allowed waht
phototrophs to diversify extensively.
120
evolved a photosystem capable of oxygenic photosynthesis
cyanobacterial lineage by 2.5–3.3 bya
121
oxygenic photosynthesis
H2O supplanted H2S as the reductant for CO2, thereby generating O2 as a waste product.
122
caused the greatest
change ever in the history of our biosphere and set the stage for the evolution of even newer forms of
life that evolved to exploit the energy available from O2 respiration.
The origin of oxygenic photosynthesis and the rise of O2 in Earth’s atmosphere
123
were likely the first photosynthetic organisms
cyanobacteria
124
containing what appear to be fossil cyanobacteria
stromatolites from as old as 3.5 by
125
many stromatolites with what appear to be fossil cyanobacteria date to about
2.5 bya
126
contain microfossils
that appear remarkably similar to modern species of
phototrophic bacteri
ancient stromatolites
127
what do one-billion-year-old microfossils from central
Australia resemble
filamentous
cyanobacteria.
128
cellular structure is similar
to that of certain modern green algae, such as
Chlorella species.
Microfossils of eukaryotic cells from the same
rock formation
129
In the absence of O2, most of Earth’s what is the state of iron
- iron would have been
present in reduced forms (Fe0 and Fe2+)
- large amounts of
iron would have been dissolved in Earth’s anoxic oceans
130
indicates that oxygenic
photosynthesis first appeared on Earth several hundred million
years before significant levels of O2 appeared
Molecular and chemical evidence
131
could not accumulate in
the atmosphere
the O2 that cyanobacteria produced
132
the O2 that cyanobacteria produced could not accumulate in
the atmosphere. why?
because it reacted spontaneously with the
reduced iron minerals in the oceans to make iron oxides
133
O2 levels had risen to one part per million, a tiny amount by
present-day standards, but enough to initiate the Great Oxidation Event
2.4 bya
134
rise of O2 to one part per million is enough to initiate what
Great Oxidation Event
135
yielded O2
metabolism of cyanobacteria
136
what does the O2 yielded by the metabolism of cyanobacteria oxidize
oxidized
reduced minerals containing Fe2+ to iron oxides containing Fe3+.
137
oxidation of
reduced minerals containing Fe2+ to iron oxides containing Fe3 + led to what fromation
banded iron formations, laminated sedimentary rocks
formed in deposits of iron- and silica-rich materials and an
indication of the release of O2 into the oceans
138
As O2 accumulated on Earth, the atmosphere gradually changed from
anoxic to oxic
139
what happened to bacteria and archaea wehrn the atmosphere gradually changed from anoxic to oxic
- unable to adapt to this change were increasingly restricted to anoxic habitats because of the toxicity of O2 and because it chemically oxidized the reduced substances upon which
their metabolisms depend
140
Other schemes of metabolism
sulfide oxidation, nitrification, and the various other
aerobic chemolithotrophic processes
141
Microbes that evolved the capacity to respire O2
gained a tremendous energetic advantage because of what
high reduction potential of the O2/H2O couple
(aerobic respiration)
142
reproduce far more rapidly than
anaerobes
aerobes
143
provided protection from
UV radiation and allowed life to expand to regions at and near the Earth’s surface .
formation of the ozone layer (O3)
144
The oldest date for the origin of life is fixed by
the time of Earth’s origin
145
minimum time for the
origin of oxygenic photosynthesis is fixed by
Great Oxidation Event
146
Major landmarks in biological evolution,
Earth´s changing geochemistry, and
microbial metabolic diversification
1. phanerozoic
2. proterozoic
3. archaean
4. hadean
147
phanerozoic
- 0.5 bya
-extinction of dinosaurs
- orginis of first animals
148
proterozoic
- start of cambrian explosion
- evidence for multicellular eukaryotes
- ozone shield forming (2.0 bya)
- start of the great oxidation event
- 0.5-2.5 bya
149
archaean
- origins of cyanobacteria and oxygenic photsnth.
- ori. of anoxygenic photsnths.
- divergence of bacteria and archaea
- 2.5 - 3.6(?)
150
hadean
-origin of cellular life
- form. of crust and oceans
-form. of earth
- 3.6 - 4.6(?)
151
first appear in the fossil record
about 2BYA, long after prokaryotic cells
eukaryotes
152
provides evidence of
common ancestry of life on Earth, with
eukaryotes splitting from Archaea about 2
BYA
DNA sequencing
153
model for
how at least some of the eukaryotic cell
organelles came to exist
endosymbiotic theory
154
endosymbiotic theory ex.
the
mitochondrion of modern-day eukaryotes
arose from the stable incorporation of a
bacterium capable of aerobic respiration into
the cytoplasm of early eukaryotic cells.
155
Evolutionary origins of microorganisms remained
a mystery until it was discovered that
molecular sequences are a record of evolutionary
history.
156
occur at random and
accumulate over time, causing heritable changes
in the sequence of DNA ; this ultimately results in
evolution
Mutations
157
have similar DNA sequences
Organisms that share a recent ancestor
158
have more dissimilar
DNA sequences.
organisms that
are more distantly related
159
reconstructed by analyzing similarities in
their nucleotide sequences
the
evolutionary history, or phylogeny,
160
beneficial to the early eukaryotic cells because they increased the cell’s
respiratory capacity.
Endosymbiotic mitochondria
161
became the ancestors of all living Eukarya.
early mitochondria-containing cells
162
all eukaryotic cells have ?
mtchndria
163
mitchndra were subsequently lost in certain
lineages of
anaerbc mcrbal eukaryotes
164
had a major impact on the evolution of life.
second endosymbiotic event
165
arose from the
incorporation of a cyanobacterium-like cell into the cytoplasm of a eukaryotic lineage
chloroplast
166
incorporation of a cyanobacterium-like cell into the cytoplasm of a eukaryotic lineage, triggered the
origin of photosynthesis within Eukarya, the 3rd Domain of life
167
have descended from the lineage of cells that
acquired endosymbiotic chloroplasts
All phototrophic eukaryotes, including plants and algae
168
intimately associated with the endosymbiotic
origins of organelles,
Atmospheric oxygen
169
how atmospheric oxygen is intimately associated with the endosymbiotic
origins of organelles
being consumed by the ancestor of the mitochondrion and being produced by the
ancestor of the chloroplast.
170
These endosymbiotic events diversified the
metabolism of early eukaryotic cells,
171
providing aerobic respiration
mitochondria
172
providing the ability to exploit sunlight for energy.
chloroplast
173
set the stage for the diversification of Eukarya into the forms we know
today.
endosymbiotic origin of organelles
174
Basis for the divisions of geologic time
1. major changes in types of organisms found in the fossil record (each division has its own characteristic set of
commonly found fossils and unique fossil forms)
2. many of the transitions between the divisions are marked by major extinction events, where many
organisms apparently died out over a short period of time because they disappear form the fossil record from
that point on
3. although there are many major extinction events in the fossil record, by most measures five stand out
above the rest; you need to know these “big five” mass extinction events during the Paleozoic Era
175
“big five” mass extinction events during the Paleozoic Era:
- Ordovician period (488-444 MYA)
- Devonian period (416-359 MYA)
- Permian period ended with the 3rd mass extinction event (251 MYA)
- Triassic period (ended with the 4th MEE, 00MYA)
- Cretaceous period (ended with the 5th MEE, 65 MYA)
176
has been marked by many ice ages, the rise of humans, and mass
extinctions
Neogene
177
The Neogene has been marked by many ice ages, the rise of humans, and mass
extinctions; most of these mass extinctions may have been caused by the ice
age climate, humans, or both; the current mass extinction event (we are in one
now, the sixth extinction) is mostly caused by humans
Cenozoic Era (65MYA to present)
178
The Neogene has been marked by what
many ice ages, the rise of humans, and mass
extinctions
179
most of these mass extinctions may have been caused by the
ice
age climate, humans, or both
180
