Test1 Flashcards
(125 cards)
1
Q
Define Astrobiology
A
study of the origin, distribution, and evolution (past/present)
2
Q
Scientific method steps
A
observation, question, hypothesis, prediction, test
3
Q
define pseudoscience
A
any body of knowledge that claims to be scientific but doesn’t follow the scientific method
4
Q
The big bang theory supporting evidence
A
- detected radiation
2. Backwards calculation of temperature matches what the universe is made of
5
Q
what limits how much of the universe we can actually see?
A
the age of the universe
6
Q
how old do we think the universe is?
A
13.7 billion light years
7
Q
WMAP
A
Wilkinson Microwave anisotrophy probe measures fluctuation in cosmic microwave background (measured the 13.7)
8
Q
What is the structure of the universe
A
flat, membrane like
9
Q
Composition of the universe?
A
73% dark energy
23% dark matter
3.6% intergalactic gas
0.4% stars
10
Q
what does dark matter emit?
A
not enough light or radiation to detect. Likely nonbaryonic particles (atom less particles)
11
Q
what accelerates universe expansion
A
dark energy
12
Q
how many stars in milky way and observable universe
A
- 100-400 billion stars
2. > 100 billion galaxies
13
Q
speed of light?
A
2.998 x 10^8m/s
14
Q
1 AU distance
A
1.496 x 10^8 km
15
Q
ISM
A
interstellar medium: when a dead stars material is returned to where it came from
16
Q
what elements are produced by stars?
A
all elements heavier than H and He: so all organic molecules
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
18
Q
What is responsible for stellar formation?
A
gravity
19
Q
Gas composition of stellar formation
A
74% H
25% He
1% heavier elements
20
Q
Gravity condenses local clumps to form ___ then eventually stars
A
protostars
21
Q
three critical processes of protostar formation
A
- MC shrinks due to gravity and stars spinning
- spin increases, cloud flattens and becomes a circumstellar disk angular meomentum
- in the core, temp/density/pressure increase
22
Q
What temperature does the star start emitting light
A
2000-3000K
23
Q
when does a protostar start to convert H to He
A
it starts to heat up and perform thermonuclear fusion
24
Q
last steps in star formation
A
inceased temp stops gravitational collapse, gravity becomes thermal pressure
25
Main factor in determining the stars life stage:
mass
26
define main sequence
luminosity of star as a function of its surface temperature (90% of life spent here)
27
which stars uses proton-proton chain
stars <1 solar mass
28
which stars burn H via the carbon-nitrogen-oxygen chain
stars >1 solar mass, usually have a higher core temperature
29
3 dwarf planets
pluto, ceres, eris
30
solar nebula
what plants for from, a disk of gas and dust
31
times scale for gas giant formation
1-10 million years
32
time scale for rocky planet formation
100 million years
33
two methods of gas giant formation
1. core accretion
| 2. fragmentation
34
How old is the earth
4.6 billion years
35
the dynamo effect
twisting of the liquid outer core over the solid core
36
who has strong magentosphers
Earth, Jupiter, satur, Uranus, neptune
37
biggest clue as to where the water came from is the...
deurerium-hydrogen ratio
38
two theorys of where earths water came from
1. planetesimal from within1AU
| 2. planetesimals from 2-3 AU
39
first polluters
cyanobacteria
40
igneous rock
molten rock that cools and solidifes
41
metamorphic
structurally altered by high pressure or heat, but not enough to melt it
42
sedmimentary
gradual compression (75% of all earth covered)
43
alpha decay
| beta decay
1. He nucleus is ejected (2 protons/2neutons)
| 2. absorbs of emits electron
44
how old are the oldest fossils
3.85 Ga
45
Where are the oldest rocks found
Acasta Gneiss (Canada)
46
Four Eon's
Hadean, Archaen, Proterozoic, Phanerozoic
47
Hadean
covers formation of the earth up until where life forms
48
Archaean
marked by the creation of life to where the atomosphere became rish in oxygen
49
Proterozoic
ends at the rise of the animals/eukaryotes
50
Phanerozoic
rise of animals to present
51
precambrian
hedean, archean, proterzoic
52
What does life require
1. capacity for self replication
| 2. capacity to undergo Darwinian evolution
53
preference for L AA
starlight is polarized in one direction and photolysis occurs more in R AA
54
what elements did miller use to make the atmostphere
methane, amonnia, water, hydrogren
55
How do we know what we know about when life started
fossil records, isotopic dating, chirality
56
what did urey create
all amino acids
all 5 bases in DNA and RNA
complex lipids
57
what was found in life but not the murchinson meteorite
polysacchardies, proteins, nucleic acids
58
formation of the earth
4.5 Ga
59
First DNA life
3.5 Ga
60
Two competing theories on origin of life
1. metabolism first
| 2. replication first
61
Catalysts
proteins, RNA, lipids, clays
62
under the right conditions, AA could sponaneously self assemble to form
protenoids
63
Characterisitscs of protenoids
1. double layered outer boundry
2. electrical potential differences
3. house chemical reactions
64
Production of lipids
1. extaterrestrial (ISM)
2. photobiotically
3. volcancos/hydrothermal vents
65
non covalent amphiphillic aggregates with catalytic properies
lipozymes
66
What roles did minerals play in life
1. mineral surfaces as adsorbents
2. catalyst
3. Chiral selectivity
4. protection
67
what minerals catalyze nitrogen heterocycles (pyrimidine)
feldspar, montmorillonite, rutile
68
montomorillonite clays accerate the formation of
fluid filled sacs
69
what forms pyruvate
CO and FeS
70
Major functions of RNA
1. catalyst
2. encoding
3. regulatory
71
smallest known self-catalyzing ribozyme
hammerhead
72
Major difference between RNA and DNA
presence of a hydroxl group at position 2
73
pairs of these RNA molecules can self replicate
R3C ligase
74
Riboswatches
RNA sensors that affect gene expression
75
CRISPR
clustered regulatory interspaced palindromic repeats
| neutralizes invading viruses
76
purines are abiotically produced from
HCN, NH3, H2O
77
Pyrimadines are produced from
cyanoacetylene
78
sugars are produced from
formaldehyde through the formose reaction
79
why is DNA better than RNA
1. long term storage
2. lower replication error rate
3. more stable
80
production of dNTPs
dUMP --- thymidylate synthases --> dTMP --- ribonucelotides reductase-->dNTPs
81
the appearance of T-DNA likely had two origins
1. Thy x
| 2. Thy A
82
U-DNA to T-DNA is
cytosine deamination
83
Major elements of LUCA
C,H,N,O,P,S
84
many thought LUCA had DNA because of
ribonucleotide reductases
85
4 conserved universal components of DNA replication
DnaA, Poll-A, HolB, Rec A
86
What is the limiting factor for RNA genome
limited coding capacity
87
Temperatures for LUCA
mesophillic or moderatley thermophillic
88
The evolution of single-celled eukaryotes and muliti-cellularity brought:
- increased intracellular structural variety
| - cell differentiation and specialization
89
When was the rise in O2
2.4Ga
90
source of atmospheric free oxygen
oxygenic photosynthesis
91
When did photosynthesis start
3-2.7Ga
92
what is the biomarker from photosynthetic cyanobateria
hopanoids
93
describe high O2 atomosphere in terms of sulfur
Sulfur is oxidized to sulfuric acid and accumulates in the ocean as sulfate
94
describe low O2 atomosphere in terms of sulfur
leaves atmosphere as H2S and H2SO4 and accumulates in soils
95
When was the change in sulfur isotope ratios in rocks
2300 mya
96
Over time Eukaryotes increased in...
size, cellular diversity, and complexity
97
5 metagroups of Eukaryotes
Plantae, excavates, rhizaria, chromalveolates, unikonts
98
Oldest fossil eukaryote
1.87 Ga
| Grypania
99
What are steranes
sterols produced by eukaryotes only and date back o 2.7Ga
100
Two theories for the root of LECA
Unikonts or Plantae
101
LECA most similar to what organism
Naegleria gruberi
102
______ and _________ place Archaea and Eukarya closer together on the tree of life
rRNA genes and polymerases
103
Archaeal genes in Eukaryotes
translation, transcription, replication, splicing
104
Bacterial genes in Eukaryotes
metabolic enzymes
105
Parental archaea probably....
mesophillic and in a diverse bacterial community
106
Two scenarios for Eukaryogenesis
A. archezoan
| b. symbiogenesis
107
Advantage of having mitrochondira
more hydrogen
| 18-fold increase in ATP production
108
RNA interference system appear to come from
archaeo-bacterial chimeras
109
Circumstellar habitable zone
range of distances from a star where liquid water can exist on a planet surface
110
Requirements for a CHZ
1. temperature: balance solar radiation and temperature
| 2. luminosity: energy emitted by the star per second
111
Inner zone of CHZ
0.95AU
| determined by photolysis (breakdown of water to H and O)
112
Outer zone of CHZ
dependent on carbon dioxide thermostat
113
what keeps CO2 in the atmosphere?
carbon recycling via volcanism and plate teconics
114
planetary temperature =
temperature + greenhouse warming
115
what is earths average global surface temperature
288k
116
What explains snow ball earth
rise in O2, collapsing methane which leads to cooler temperatures
117
how long does it take for 1 compelete carbon cycle
1 Million years
118
how do green house gases contribute to ice ages
drop in CO2, methane, NO
119
how do positions of continents contribute to ice ages
block warm water flow
120
Milankovitch cycle
obliquity, precssion, eccntricity
121
when were the two snowball earth events
1. 2.45Ga Makganyene
| 2. 800-600 Mya Marinoan
122
Evidence for Snowball earth
1. global glacial deposits
2. lack of C12, increasedC13
3. BIF
4. cap carbonates
123
Cambrian explosion
all known animal body plans appeared 545-505 mya
124
oldest known fossiled animal
ediacaria
125
causes of the cambrian explosion
1. rise in O2
2. selection pressure for hardparts
3. Hox genes : genetic complexity
