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BIO 357 - Microbiology > Microbial Evolution and Taxonomy > Flashcards

Microbial Evolution and Taxonomy Flashcards

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Biology 101 flashcards
1
Q

How old is the Earth?

A

~4.5 billion years old

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2
Q

When did water appear in liquid form?

A

~4.3 bilion years ago

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3
Q

When did microbial life begin?

A

~4.2 billion years ago

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4
Q

What are Stomatolites?

A

fossilized microbial mats - really thick layers of bacteria

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5
Q

How old are Stomatolites?

A

3.5 billion years old

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6
Q

Of what were ancient stromatolites made?

A

anoxygenic phototrophic filamentous bacteria

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7
Q

What is the Surface Origin Hypothesis?

A
  • first membrane, self-replicating cells arose out of primordial soup rich in organic and inorganic compounds in ponds
  • Against this hypothesis:
    • dramatic temp flunctuations
    • mixing from meteor impacts
    • dust clouds
    • storms
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8
Q

What is the Subsurface Origin Hypothesis?

A
  • Life originated at hydrothermal springs on ocean floor
    • conditions would have been more stable
    • steady and abundant supply of energy (H2 and H2S) may have been available
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9
Q

What is the order in which biological entities formed?

A
  1. simple molecules
    • hydrocarbons, sugars, fatty acids, amino acids, peptides, nitrogen bases
  2. RNA life
  3. RNA and proteins
  4. DNA
  5. LUCA - last universal common ancestor
  6. Diversification of molecular biology, lipids and cell wall structure
    • early bacteria and early archaea
  7. Dispersal to other habitats
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10
Q

What is the RNA World Theory?

A
  • proposes that RNA was first nucleic acid
    • RNA can bind small molecules
    • RNA has catalytic activity, may have catalyzed own synthesis
  • DNA eventually became the genetic norm
    • b/c its more stable
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11
Q

Metabolism of Primitive Cells

A
  • chemolithoautotrophic
    • Carbon from CO2
    • energy from H2
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12
Q

When did the LUCA btwn Bacteria and Archaea diverge?

A

~3.8 billion years ago

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13
Q

When did cyanobacteria begin to generate O2?

A

~2.7 billion years ago

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14
Q

What is the Great Oxidation Event?

A

accumulation of O2 concentration to 1 part per million

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15
Q

When did the Great Oxidation Event occur?

A

2.4 billion years ago

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16
Q

Why did the O2 take so long to accumulate?

A

O2 had to react w/ FeS and FeS2 first

also O2 was gobbled up as soon as made at first

17
Q

When did Eukaryotes first appear?

A

~2 billion years ago

18
Q

What is the “Other Hypothesis” regarding the origin of eukaryotes?

A
  • eukaryotes began as nucleas-bearing lineage that late aquired mitochondria and chloroplasts by endosymbiosis
19
Q

What is the Hydrogen Hypothesis?

A
  • eukaryotic cell arose from engulfment of a H2-producing cell of Bacteria by a H2-consuming cell of Archaea
    • made mitochondria
  • later formed nucleus
  • formed chloroplast by endosymbiosis
20
Q

Why is the Hydrogen Hypothesis more likely than the “Other Hypothesis?”

A
  • eukaryotes have similar lipids and energy metabolisms to bacteria
  • eukaryotes have transcription and translational machinery most similar to archaea
21
Q

Phylogeny

A
  • evolutionary history of a group of organisms
  • inferred from nucleotide sequence data
  • Assumptions:
    • all organisms evolved from the LUCA
    • DNA sequences represent a record of the organism’s ancestry
22
Q

Molecular Clocks (chronometers)

A
  • certain genes and proteins that are measures of evolutionary change
    • need to be…
      • functionally constant
      • sufficiently conserved
      • suffient length
      • found in all domains of life
  • most widely used ones are small subunit rRNA (SSU rRNA)
    • 16S rRNA or 18S rRNA
  • Assumptions…
    • mutations occur at constant rate
    • mutations are neutral
    • mutations are random
23
Q

BLAST (Basic Local Alignment Search Tool)

A
  • alignment algorithm to compare sequence of interest to known sequences in database
24
Q

What is the bacterial origin of mitochondria and chloroplasts?

A

Mitochondria arose from Proteobactreia

Chloroplasts arose from Cyanobacteria

25
Q

What are the 2 major group of the Domain Archaea?

A

Crenarchaeota

and

Euryarchaeota

26
Q

Taxonomy

A

the science of identification, classification, and nomenclature

27
Q

Systematics

A

the study of the diversity of organisms and their relationships

links phylogeny w/ taxonomy

28
Q

What is the definition of a prokaryotic species?

A

>70% DNA-DNA hybridization

>97% 16S rRNA gene sequence

share multiple phenotypes

29
Q

FAME (Fatty Acid Methyl Ester)

A

analysis of fatty acids as phenotype analysis

variation in type and proportion of fatty acids present in membrane lipids

30
Q

Multilocus Sequence Typing (MLST)

A
  • method in which many diff “housekeeping genes” from an organism are sequenced
    • recA and gyrB included
  • very good specificity; very sensitive
31
Q

Isolate

A

single clonal population w/ little genetic info known

32
Q

Strain

A

single isolate or group of isolates w/ similar genetic/phenotypic traits that have been cultivated in the lab

33
Q

Ecotype (Evocar)

A

population of cells that share a particular resource

34
Q

Serotype (Serovar)

A

group of closely related microorganisms distinguished by characteristic set of outer membrane proteins

BIO 357 - Microbiology (8 decks)

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