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Astrobiology > Test1 > Flashcards

Test1 Flashcards

1
Q

Define Astrobiology

A

study of the origin, distribution, and evolution (past/present)

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2
Q

Scientific method steps

A

observation, question, hypothesis, prediction, test

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3
Q

define pseudoscience

A

any body of knowledge that claims to be scientific but doesn’t follow the scientific method

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4
Q

The big bang theory supporting evidence

A
  1. detected radiation

2. Backwards calculation of temperature matches what the universe is made of

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5
Q

what limits how much of the universe we can actually see?

A

the age of the universe

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6
Q

how old do we think the universe is?

A

13.7 billion light years

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7
Q

WMAP

A

Wilkinson Microwave anisotrophy probe measures fluctuation in cosmic microwave background (measured the 13.7)

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8
Q

What is the structure of the universe

A

flat, membrane like

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9
Q

Composition of the universe?

A

73% dark energy
23% dark matter
3.6% intergalactic gas
0.4% stars

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10
Q

what does dark matter emit?

A

not enough light or radiation to detect. Likely nonbaryonic particles (atom less particles)

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11
Q

what accelerates universe expansion

A

dark energy

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12
Q

how many stars in milky way and observable universe

A
  1. 100-400 billion stars

2. > 100 billion galaxies

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13
Q

speed of light?

A

2.998 x 10^8m/s

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14
Q

1 AU distance

A

1.496 x 10^8 km

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15
Q

ISM

A

interstellar medium: when a dead stars material is returned to where it came from

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16
Q

what elements are produced by stars?

A

all elements heavier than H and He: so all organic molecules

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17
Q

material the stars are made up of is ___ and ___ altered within the stars throughout the course of their lifetime and at their deaths

A

physically and chemically

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18
Q

What is responsible for stellar formation?

A

gravity

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19
Q

Gas composition of stellar formation

A

74% H
25% He
1% heavier elements

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20
Q

Gravity condenses local clumps to form ___ then eventually stars

A

protostars

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21
Q

three critical processes of protostar formation

A
  1. MC shrinks due to gravity and stars spinning
  2. spin increases, cloud flattens and becomes a circumstellar disk angular meomentum
  3. in the core, temp/density/pressure increase
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22
Q

What temperature does the star start emitting light

A

2000-3000K

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23
Q

when does a protostar start to convert H to He

A

it starts to heat up and perform thermonuclear fusion

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24
Q

last steps in star formation

A

inceased temp stops gravitational collapse, gravity becomes thermal pressure

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25
Q

Main factor in determining the stars life stage:

A

mass

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26
Q

define main sequence

A

luminosity of star as a function of its surface temperature (90% of life spent here)

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27
Q

which stars uses proton-proton chain

A

stars <1 solar mass

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28
Q

which stars burn H via the carbon-nitrogen-oxygen chain

A

stars >1 solar mass, usually have a higher core temperature

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29
Q

3 dwarf planets

A

pluto, ceres, eris

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30
Q

solar nebula

A

what plants for from, a disk of gas and dust

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31
Q

times scale for gas giant formation

A

1-10 million years

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32
Q

time scale for rocky planet formation

A

100 million years

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33
Q

two methods of gas giant formation

A
  1. core accretion

2. fragmentation

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34
Q

How old is the earth

A

4.6 billion years

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35
Q

the dynamo effect

A

twisting of the liquid outer core over the solid core

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36
Q

who has strong magentosphers

A

Earth, Jupiter, satur, Uranus, neptune

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37
Q

biggest clue as to where the water came from is the…

A

deurerium-hydrogen ratio

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38
Q

two theorys of where earths water came from

A
  1. planetesimal from within1AU

2. planetesimals from 2-3 AU

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39
Q

first polluters

A

cyanobacteria

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40
Q

igneous rock

A

molten rock that cools and solidifes

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41
Q

metamorphic

A

structurally altered by high pressure or heat, but not enough to melt it

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42
Q

sedmimentary

A

gradual compression (75% of all earth covered)

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43
Q

alpha decay

beta decay

A
  1. He nucleus is ejected (2 protons/2neutons)

2. absorbs of emits electron

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44
Q

how old are the oldest fossils

A

3.85 Ga

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45
Q

Where are the oldest rocks found

A

Acasta Gneiss (Canada)

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46
Q

Four Eon’s

A

Hadean, Archaen, Proterozoic, Phanerozoic

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47
Q

Hadean

A

covers formation of the earth up until where life forms

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48
Q

Archaean

A

marked by the creation of life to where the atomosphere became rish in oxygen

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49
Q

Proterozoic

A

ends at the rise of the animals/eukaryotes

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50
Q

Phanerozoic

A

rise of animals to present

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51
Q

precambrian

A

hedean, archean, proterzoic

52
Q

What does life require

A
  1. capacity for self replication

2. capacity to undergo Darwinian evolution

53
Q

preference for L AA

A

starlight is polarized in one direction and photolysis occurs more in R AA

54
Q

what elements did miller use to make the atmostphere

A

methane, amonnia, water, hydrogren

55
Q

How do we know what we know about when life started

A

fossil records, isotopic dating, chirality

56
Q

what did urey create

A

all amino acids
all 5 bases in DNA and RNA
complex lipids

57
Q

what was found in life but not the murchinson meteorite

A

polysacchardies, proteins, nucleic acids

58
Q

formation of the earth

59
Q

First DNA life

60
Q

Two competing theories on origin of life

A
  1. metabolism first

2. replication first

61
Q

Catalysts

A

proteins, RNA, lipids, clays

62
Q

under the right conditions, AA could sponaneously self assemble to form

A

protenoids

63
Q

Characterisitscs of protenoids

A
  1. double layered outer boundry
  2. electrical potential differences
  3. house chemical reactions
64
Q

Production of lipids

A
  1. extaterrestrial (ISM)
  2. photobiotically
  3. volcancos/hydrothermal vents
65
Q

non covalent amphiphillic aggregates with catalytic properies

66
Q

What roles did minerals play in life

A
  1. mineral surfaces as adsorbents
  2. catalyst
  3. Chiral selectivity
  4. protection
67
Q

what minerals catalyze nitrogen heterocycles (pyrimidine)

A

feldspar, montmorillonite, rutile

68
Q

montomorillonite clays accerate the formation of

A

fluid filled sacs

69
Q

what forms pyruvate

A

CO and FeS

70
Q

Major functions of RNA

A
  1. catalyst
  2. encoding
  3. regulatory
71
Q

smallest known self-catalyzing ribozyme

A

hammerhead

72
Q

Major difference between RNA and DNA

A

presence of a hydroxl group at position 2

73
Q

pairs of these RNA molecules can self replicate

A

R3C ligase

74
Q

Riboswatches

A

RNA sensors that affect gene expression

75
Q

CRISPR

A

clustered regulatory interspaced palindromic repeats

neutralizes invading viruses

76
Q

purines are abiotically produced from

A

HCN, NH3, H2O

77
Q

Pyrimadines are produced from

A

cyanoacetylene

78
Q

sugars are produced from

A

formaldehyde through the formose reaction

79
Q

why is DNA better than RNA

A
  1. long term storage
  2. lower replication error rate
  3. more stable
80
Q

production of dNTPs

A

dUMP — thymidylate synthases –> dTMP — ribonucelotides reductase–>dNTPs

81
Q

the appearance of T-DNA likely had two origins

A
  1. Thy x

2. Thy A

82
Q

U-DNA to T-DNA is

A

cytosine deamination

83
Q

Major elements of LUCA

A

C,H,N,O,P,S

84
Q

many thought LUCA had DNA because of

A

ribonucleotide reductases

85
Q

4 conserved universal components of DNA replication

A

DnaA, Poll-A, HolB, Rec A

86
Q

What is the limiting factor for RNA genome

A

limited coding capacity

87
Q

Temperatures for LUCA

A

mesophillic or moderatley thermophillic

88
Q

The evolution of single-celled eukaryotes and muliti-cellularity brought:

A
  • increased intracellular structural variety

- cell differentiation and specialization

89
Q

When was the rise in O2

90
Q

source of atmospheric free oxygen

A

oxygenic photosynthesis

91
Q

When did photosynthesis start

92
Q

what is the biomarker from photosynthetic cyanobateria

93
Q

describe high O2 atomosphere in terms of sulfur

A

Sulfur is oxidized to sulfuric acid and accumulates in the ocean as sulfate

94
Q

describe low O2 atomosphere in terms of sulfur

A

leaves atmosphere as H2S and H2SO4 and accumulates in soils

95
Q

When was the change in sulfur isotope ratios in rocks

96
Q

Over time Eukaryotes increased in…

A

size, cellular diversity, and complexity

97
Q

5 metagroups of Eukaryotes

A

Plantae, excavates, rhizaria, chromalveolates, unikonts

98
Q

Oldest fossil eukaryote

A

1.87 Ga

Grypania

99
Q

What are steranes

A

sterols produced by eukaryotes only and date back o 2.7Ga

100
Q

Two theories for the root of LECA

A

Unikonts or Plantae

101
Q

LECA most similar to what organism

A

Naegleria gruberi

102
Q

______ and _________ place Archaea and Eukarya closer together on the tree of life

A

rRNA genes and polymerases

103
Q

Archaeal genes in Eukaryotes

A

translation, transcription, replication, splicing

104
Q

Bacterial genes in Eukaryotes

A

metabolic enzymes

105
Q

Parental archaea probably….

A

mesophillic and in a diverse bacterial community

106
Q

Two scenarios for Eukaryogenesis

A

A. archezoan

b. symbiogenesis

107
Q

Advantage of having mitrochondira

A

more hydrogen

18-fold increase in ATP production

108
Q

RNA interference system appear to come from

A

archaeo-bacterial chimeras

109
Q

Circumstellar habitable zone

A

range of distances from a star where liquid water can exist on a planet surface

110
Q

Requirements for a CHZ

A
  1. temperature: balance solar radiation and temperature

2. luminosity: energy emitted by the star per second

111
Q

Inner zone of CHZ

A

0.95AU

determined by photolysis (breakdown of water to H and O)

112
Q

Outer zone of CHZ

A

dependent on carbon dioxide thermostat

113
Q

what keeps CO2 in the atmosphere?

A

carbon recycling via volcanism and plate teconics

114
Q

planetary temperature =

A

temperature + greenhouse warming

115
Q

what is earths average global surface temperature

116
Q

What explains snow ball earth

A

rise in O2, collapsing methane which leads to cooler temperatures

117
Q

how long does it take for 1 compelete carbon cycle

A

1 Million years

118
Q

how do green house gases contribute to ice ages

A

drop in CO2, methane, NO

119
Q

how do positions of continents contribute to ice ages

A

block warm water flow

120
Q

Milankovitch cycle

A

obliquity, precssion, eccntricity

121
Q

when were the two snowball earth events

A
  1. 2.45Ga Makganyene

2. 800-600 Mya Marinoan

122
Q

Evidence for Snowball earth

A
  1. global glacial deposits
  2. lack of C12, increasedC13
  3. BIF
  4. cap carbonates
123
Q

Cambrian explosion

A

all known animal body plans appeared 545-505 mya

124
Q

oldest known fossiled animal

125
Q

causes of the cambrian explosion

A
  1. rise in O2
  2. selection pressure for hardparts
  3. Hox genes : genetic complexity

Astrobiology (2 decks)

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