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BIOL 215 > Origins of Life > Flashcards

Origins of Life Flashcards

1
Q

what are the three important principles in evolutionary biology?

A
  • inferring evolutionary history
  • independent evolution
  • direction in evolution
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2
Q

what is phylogeny and a phylogenetic tree?

A
  • phylogeny: the course of evolution from past to present
  • tree: graphical representation of phylogeny
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3
Q

what are the different nodes and branches in a phylogenetic tree?

A

nodes:
- internal: in between terminal and root
- terminal: go to the end
- root: connects all the ends

branches:
- internal:
terminal: go to the end

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4
Q

What type of data and methods can be used to build phylogenetic trees?

A

data:
- morphology (fossils)
- DNA

methods:
- parsimony
- maximum likelihood
- distance
- Bayesian methodology

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5
Q

What is the parsimony method based on?

A

the tree possessing the minimum number of evolutionary steps in the best tree

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6
Q

what is cladistics?

A

the method to count evolutionary steps that uses shared derived characters

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7
Q

what is a synapomorphy?

A

a shared derived character

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8
Q

what would we classify as being the most parsimonious?

A

the tree having the least amount of steps

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9
Q

what is a autopomorphy? Is it useful for building trees?

A

characteristics unique to species and no

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10
Q

what is a symplesiomorphy? is it useful to build trees?

A

a characteristic that is shared by all and no

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11
Q

what is cosmology?

A

the study of the universe

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12
Q

when is the origin of the universe?

A

13.73 bya

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13
Q

when did the Big Bang occur?

A

between 10-15 bya

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14
Q

what happened in the first 100 seconds of the universe?

A
  • universe starts expanding exponentially
  • quarks and gluons emerge
  • quarks bound into protons and neutrons
  • beginning of formation of the nuclei of He and others elements from H
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15
Q

How were heavier elements produced?

A

as the universe continued to expand, H and He condensates, which started forming protostars. As these protostars burn, they produce heavier elements (up to Fe)

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16
Q

How was the solar system formed? Include the approximate dates.

A
  • a large protostar exploded causing a supernova, which formed the solar system/sun (5-5.6 bya) – solar nebula
  • sun and accretion disc (4.6 bya)
  • condensation of nebular material creating 4 inner terrestrial planets, 4 outer gaseous planets, asteroids, comets, and dwarf planets (4.5 bya)
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17
Q

what are the Earth’s unique conditions that make it liveabe?

A
  • sun energy
  • stable climate
  • composition of elements
  • liquid water
  • iron core
  • ozone
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18
Q

Earth was initially composed of which elements?

A

Fe, Mg, Si, O

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19
Q

when did earth form? What are the oldest rock found? when did the Earth’s crust form?

A
  • earth: 4.6 bya
  • rocks: 4.28 bya
  • crust: 4.2-4.1 bya
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20
Q

What does the discovery of old zircon crystals mean?

A

some crystals date from 4.4 bya, and these require liquid water and low temperatures to from, which means that Earth must have cooled by then

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21
Q

what are different methods used to date the earth/rocks?

A

look at the formation/layering of rocks, look at fossils, and radioactive dating

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22
Q

What are the prerequisites for the origin of molecules?

A

-sun and the earth’s orbit
- chemicals
- water

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23
Q

What is the Miller-Urey experiment and what did he produce?

A

Used gases thought to compose of the earth’s atmosphere (along with all the conditions of that time) and produced 17 amino acids and all purines and pyrimidines in 1 week

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24
Q

What are some possible sites for the origin of the first molecules on Earth and why?

A
  • hydrothermal vents (thermo organisms)
  • volcanoes (sponge-like minerals that can retain and catalyze organic compounds)
  • clays (layered clay serve as polymerization template)
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25
Q

What is the panspermia hypothesis?

A

That organic molecules have originated from outer space

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26
Q

What are the three lines of evidence that support the panspermia hypothesis?

A
  1. Meteorite found to contain a variety of C compounds (purines, pyrimidines, polyols, and AAs)
  2. A meteorite from mars contained some evidence of microorganisms
  3. A variety of organic molecules in interstellar space have been identified using infrared spectroscopy (methane, methanol, formaldehyde, cyanoacetylene)
27
Q

Why is the terrestrial origin of molecules more likely than the special origin?

A

Since the chirality of molecules from space is different than those found here

28
Q

What is the RNA world model?

A

RNA molecules that were randomly assembled would acquire enzymatic properties (ribozymes) and replicate, and because of errors in copying, the RNA sequence would be altered in some copies and such mutates sequences may have altered the properties of the RNA

29
Q

What is the crepe model?

A

Model for the origin of molecules where some nucleotide stuck on clay and caused them to link through sugar-phosphate bonds. Then, caused them to attract the complementary nucleotides, which were then linked together

30
Q

How could have the RNA world turn into proteins and DNA?

A
  • RNA can store information and may have begun encoding proteins like reverse transcriptase
  • RT could then have made RNA into DNA
    -DNA is better suited than RNA to store data since chemically more stable
  • DNA can the code for many different proteins
31
Q

what are the 4 different hypothesizes for the origin of the first cells?

A
  1. membrane (made from phospholipids) formation lead to the formation of protocells by formation of vesicles in water
  2. coacervates/ laboratory studies showed that dehydrating solutions of molecules produced droplets that aggregated
  3. formation of microspheres by heating and cooling, where some underwent budding or fission and they could absorb chemicals selectively and increase in size
  4. presence of osmotic stress and electrochemical gradient lead to the formation of a stable entity
32
Q

What are the conditions for Darwin’s evolution theory?

A
  • intrinsic increase in the number of individuals within a species
  • competition for limited resources
  • survival of the few
33
Q

what is the main arguments for evolution by natural selection?

A
  • high reproductive ability but limited resources
  • so there would be competition for the few resources and there is heritable variation
  • natural selection (persistence in adaptive variation) and environmental changes
  • leads to evolution (differences in adaptation)
34
Q

what are the transitions in individuality for the following:
1. abiotic organic molecules
2. concentrating molecules
3. protocells

A
  1. sheet/droplet membranes
  2. protocells
  3. prokaryotes
35
Q

what is the primary and the secondary atmosphere?

A

primary: He and H
secondary: water and carbon dioxide

36
Q

which type of organism was said to be the first (around 3.5 bya)? What is some evidence?

A

methanogens (similar to methanococcus)
- molecular fossils
- addition of methane to the atmosphere
- O2 absent 3.5 bya (so must have organism which can survive in other gases)

37
Q

what was the first photosynthetic organism and what was its effect?

A

cyanobacteria which produced O2 that started to accumulate in the atmosphere around 2.3 bya

38
Q

the earliest form of photosynthesis was based on which element?

A

S, meaning it was anoxygenic

39
Q

what were the consequences of O2 production?

A
  • allowed for the evolution of aerobic metabolism
  • changed ocean chemistry (largely S and N before)
  • allowed formation of ozone (protection from UV)
  • poisoned environment (anaerobic organisms had to get refuge elsewhere)
  • organism had to evolve mechanisms to detoxify the by-products of O2 (superoxide, hydrogen peroxide)
40
Q

Why is liquid water a requirement of life?

A
  • is majority of organism’s mass
  • chemical reactions necessary for life occurs in water
  • water is the universal solvent
41
Q

why is energy an important requirement of life?

A
  • is used to replicate/move/acquire other resources…
  • rate of energy use influences the rate of growth, which is a factor that affects the relative abundance of the organism in the environment
  • rate at which organisms can take in energy is limited (can be limited due to external or internal constraints)
42
Q

what is the “trade-off” that organisms must do relative to energy use?

A

because energy intake is limited, organisms cannot simultaneously maximize all the life’s functions: so like if they allocate energy to reproduce, it reduces the amount of energy available for defense

43
Q

what are autotrophs?

A

obtain C by inorganic sources (like CO2)

44
Q

what are heterotrophs?

A

obtain C from organic sources (like carbohydrates, proteins, and fats)

45
Q

what are the three main sources of energy used by organism?

A
  1. light energy
  2. organic chemical energy
  3. inorganic chemical energy
46
Q

why are elements a requirement of life?

A

they are used to construct cellular constituents and in biochemical reactions that are necessary for survival

47
Q

What is an essential element? and how many elements do organism require?

A

an element that is required by an organism to complete its life cycle
- 28 elements

48
Q

what is hypothesized to be the conditions for the earliest life? what type of organism would live in this condition?

A
  • H2, CO2, N2, and S gases, anaerobic and hot
  • a chemolithoautotroph (obtained energy and C from inorganic sources)
49
Q

What is the endosymbiotic theory?

A

mitochondria and chloroplasts were at one time free-living bacteria that were engulfed by archea and evolved an obligate symbiosis

50
Q

what are the differences between prokaryotes and eukaryotes?

A
  • prokaryotes: no nucleus/organelles/microtubules, have 70S ribosomes, have outer cell wall composed of peptidoglycans, are small, DNA in single chromosome, divide by binary fission
  • eukaryotes: have organelles/nucleus, mitosis, 80S ribosome
51
Q

what is evidence for the endosymbiotic theory?

A
  1. mito and chloro contain their own DNA that is similar to bacteria DNA (is circular with no histones)
  2. are surrounded by a double membrane (and inner looks like bacterial membrane)
  3. electron transport chain of mitochondria is located n the inner membrane and is in the outer membrane of bacteria
  4. show antibiotic sensitivity
  5. have 70S ribosomes
52
Q

what are mitochondria and chloroplasts said to originate from?

A
  • mito: proteobacterium
  • chloro: cyanobacteria
53
Q

Why is it difficult to classify microorganisms? What are some solutions?

A
  • since they are morphologically simple
  • DNA proposed to classify since is in all organisms and large enough to record useful info
54
Q

What are the three domains? What is used to classify within each domain?

A

Bacteria, archaea, eucarya
- rRNA is used

55
Q

What is horizontal gene transfer and how can this occur?

A
  • the transfer of genes not from parent to offspring
  • can occur during endosymbiosis by a virus or a small circular DNA (plasmid)
56
Q

What are lokiarchaeota?

A

A new group of archaea organisms first identified near deep-sea vents off the coast of Norway

57
Q

Did oxygen accumulate quickly in the atmosphere? Why or why not?

A

No since it reacted first with Fe in the sea and with reduced volcanic gases

58
Q

When was the great oxidation event?

A

2.45 bya

59
Q

What are the requirements of life?

A
  • liquid water
  • energy
  • elements
60
Q

What are the main differences between the three domains?

A
  • bacteria and archaea are both procaryotes but archaea are adapted for harsh environments
  • eukarya are eukaryotes
61
Q

What are the main examples of archaea?

A
  • lokiarchaeota
  • euryarchaeota
62
Q

What are the main examples of bacteria?

A
  • proteobacteria
  • Cyanobacteria
63
Q

What are the main examples of eukarya?

A
  • Plants
  • animals
  • fungi
  • protists
64
Q

What are the 5 kingdoms of eukarya?

A
  • plantae
  • excavates
  • rhizaria
  • unikonts
  • chromalveolates

BIOL 215 (6 decks)

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