Chapter 16 Flashcards

1
Q

Early Earth

A

Forma5on of earth—4.5 bya

•  Microbial life—found in fossils 3.5 billion years old

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2
Q

Stromatolites

A

Microbial mats
of layers of filamentous
microbes and minerals

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3
Q

Subsurface origin of life hypothesis

A

Life originated at hydrothermal springs on
ocean floor •  Stable condi5ons
•  Steady and abundant supply of energy (e.g., H2
and H2S)

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4
Q

RNA world and lipid vesicles

A

RNA world theory
– RNA can bind small molecules (e.g., ATP, other nucleo5des)
– RNA has cataly5c ac5vity; may have catalyzed its own synthesis
•  Lipid vesicles
Last universal common ancestor (LUCA)

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5
Q

Possible scheme for energy genera5on in primi5ve cells

A

Abundant H2 and FeS

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6
Q

Endosymbio5c hypothesis

A

Mitochondria and chloroplasts of eukaryotes arose from engulfment of bacteria into other cells
•  Prokaryo5c ribosomes (70S) •  Bacterial 16S ribosomal RNA •  Ribosomes inhibited by same an5bio5cs •  Covalently closed, circular DNA

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7
Q

Endosymbio5c hypothesis #2—hydrogen hypothesis

A

Accounts for •  Bacterial lipids •  Archaeal
transcrip5on and transla5on
•  Bacterial energy genera5on
•  Favored hypothesis

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8
Q

Evolu5on

A

Descent with modifica5on

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9
Q

Fitness

A

survival capacity or reproduc5ve ability
– Harmful muta5ons—lower fitness – Beneficial muta5ons—increase fitness – Neutral muta5ons—do not affect fitness,
accumulate in genome

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10
Q

Gene duplica5on •  Gene loss

A

obligate symbionts and parasites •  Horizontal gene transfer

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11
Q

  Environments select organisms that

A

survive and successfully compete and reproduce

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12
Q

Evolution occurs rapidly in microbes because of

A

Large popula5ons – Fast reproduc5on

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13
Q

Phylogeny

A

Inferred evolu5onary history •  Assump5ons:

– All organisms descended from LUCA – Sequence of DNA is record of organism’s ancestry

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14
Q

Genes used in phylogene5c analysis

A

Small subunit rRNA (SSU rRNA)
– 16S rRNA in prokaryotes – 18S in eukaryotes
– Universally distributed – Func5onally constant – Sufficiently conserved
– Adequate length

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15
Q

Genes used in phylogene5c analysis

A

EF-‐‐Tu•  Hsp60 •  tRNA synthetases

•  gyrB •  recA

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16
Q

Molecular clocks

A

assumes that changes accumulate at a constant rate, are neutral, are random—combine data with geologic evidence

17
Q

Evolu5onary analysis

A

Obtain sequences through PCR

– Oligonucleo5de primers

18
Q

Microbial systema5cs

A

Iden5fica5on of new bacterial species:
– Genotypic—gene sequences – Phylogene5c—evolu5onary framework
– Phenotypic—morphological, metabolic, physiological, and chemical characteris5cs

19
Q

Biological species concept

A

Interbreeding popula5on of organisms that is reproduc5vely isolated from other interbreeding popula5ons
– Not valid for haploid organisms

20
Q

Phylogene5c species concept

A

Group of strains that cluster closely with each other and are dis5nct from other strains

21
Q

Ecotype

A

cells in a popula5on that

share a par5cular resource

22
Q

Prokaryo5c species

A

Defined as strains with
– 70% or greater DNA-‐‐DNA hybridiza5on – 97% or greater iden5ty in 16S rRNA sequence
•  Over 7,000 known species of Bacteria and Archaea
•  Possibly up to 100,000 species

23
Q

Binomial system of nomenclature

A

  Carl Linnaeus •  Genus names and species epithets •  La5n or La5nized Greek deriva5ons •  Italicized •  Staphylococcus aureus means “a bunch of
grapes”, “berry”, and “golden”
•  IJSEM approval required