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Microbiology > test 3 lecture 16 > Flashcards

test 3 lecture 16 Flashcards

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Biology 101 flashcards
1
Q

what does abiogenesis or biopoiesis or Ool mean

A

the natural process of life arising from non-living matter, such as simple organic compounds

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2
Q

before the first cells could evolve , what fundamental conditions were needed

A

essentail elements
continual source of energy
temperature range permitting liquid water

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3
Q

why were essential elements needed for origins of life

A

to compose organic molecules

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4
Q

why was a continual source of energy needed for origins of life

A

life requires continual input of energy, which ultimately is dissipated as heat

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5
Q

why was temperature range permitting liquid water needed for origins of life

A

metabolic reactions cease at temps that are either too high or too low

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6
Q

when was the solar system formed

A

4.6 billion years ago

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7
Q

what made up the early atmosphere

A

primarily of CO2

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8
Q

what makes up the atmosphere now

A

CO2, N2, and O2

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9
Q

how do we have the compounds in the atmosphere now

A

contributions from living organisms

heavy metals created from bursting stars

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10
Q

how did temp affect the atmosphere

A

atmospheric gases absorb light and convert the energy to heat, raising the temp of the surface and atmosphere

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11
Q

what could have caused the green house effect

A

early atmosphere had high CO2 making it very hot

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12
Q

what kept the atmosphere temp down in the beginning of time

A

CO2 rose temp but with microbial consumption of CO2 and produce N2 and O2 kept temp down
possibly causing ice age

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13
Q

when was the hadean eaon

A

4.5 to 3.8 billion years ago

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14
Q

what happened during the hadean eon

A

repeated bombardment of meteorite

cycles of vaporizing ocean, cooling and condensation

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15
Q

when was the archean eon

A

3.8 to 2.5 billion years ago

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16
Q

what is significant during the archean eon

A

earths crust become solid
marked first period of stable oceans
earliest geological evidence for life from rock strata

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17
Q

what is the key ingredient of life during early earth’s existence

A

liquid over range of temps and dissolves inorganic and organic material

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18
Q

what is stromatolites

A

the earliest forms of life (bacterial communities) for which we have clear fossil evidence

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19
Q

how are stromatolites formed

A

layers of phototrophic microbial communities grew and died

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20
Q

what are the different layers of stromatolites

A

outside: oxygenic phototrophs (diatoms, cyanobacteria)
inside: sulfate reducing bacteria

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21
Q

what do stromatolites not reveal

A

they are deformed and dont reveal cell structures

22
Q

what are the 4 geological evidences for early life

A

stromatolites
microfossils
biosignatures/ biological signatures
oxidation state

23
Q

what is the most convincing evidence of early microbial life

A

microfossils

24
Q

what is in a microfossil

A

minerals precipitated and filled in the form of ancient microbial cells

25
Q

how can you tell how old a microfossil is

A

radioisotope decay

26
Q

how far back do microfossils go back

A

2.0 to 3.2 billion years ago

27
Q

what do they say about microfossils that are older than 2.0 billion years

A

metamorphic rock

microfossil interpretation controversial

28
Q

what are biosignatures

A

chemical indicators of life

29
Q

what are isotope ratios

A

ratios between certain isotopes of a given element can be altered by biological activity

30
Q

what is cyanobacterial hopanoids

A

steroid like membrane molecules that are particularly durable and may last within rock formations for hundred of millions of years

31
Q

how are elements are defined

A

number of protons in their nucleus

protons+neutrons= atomic weight

32
Q

what are isotopes

A

elements with different numbers of neutrons

33
Q

what type of elements have at least two stable isotopes with lightest being the most abundant

A

most environmentally relevant

H C N O S Cl

34
Q

what is special about 2-methylhopanoids

A

both oxygenic and anoxygenic phototrophs have them
may be able to identify biological material but may not be good biomarker for differentiating among different types of cyanobacteria

35
Q

what was the oxidation state like in early life

A

entry of O2 into earth’s biosphere arose gradually in the oceans
fluctuated with cycles of aerobic and anaerobic metabolism

36
Q

what does molecular phylogeny mean

A

genetic relatedness

37
Q

what are clades

A

branching groups of related organisms

38
Q

what is a monophyletic group

A

a group of species that share a common ancestor

39
Q

what is a phylogeny

A

the full description of branching divergence of a species

40
Q

populations of organisms diverge from each other through several fundamental mechanisms such as

A

random mutations
natural selection
reductive evolution

41
Q

what are random mutations

A

dna changes through rare mistakes as the chromosome replicates

42
Q

what is natural selection

A

in a given environment, natural selection favors organisms that produce more offspring

43
Q

what is reductive evolution

A

in the absence of selection for a trait, the genes encoding the trait accumulate mutations without affecting the organisms reproductive success
leads to loss or mutation of DNA encoding unselected traits

44
Q

what is a molecular clock

A

the temporal info contained in a macromolecular sequence

45
Q

what is maximum parsimony

A

the best fit tree is defined as the one requiring the fewest mutations to fit the data

46
Q

what is maximum likelihood

A

the probability that such a tree would have produced the observed DNA sequences

47
Q

what is horizontal gene transfer

A

acquisition of a piece of DNA from another cell

48
Q

what is vertical gene transfer

A

the transmission of an entire genome from parent to offspring

49
Q

what are informational genes

A

encode products essential for transcription and translation

50
Q

what are operational genes

A

encode products that govern metabolism, stress response, and pathogenicty

Microbiology (16 decks)

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