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BIOL 240 Microbiology > Topic 1 - Microbial World > Flashcards

Topic 1 - Microbial World Flashcards

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Biology 101 flashcards
1
Q

What features make SSU rRNA gene sequences ideal for phylogenetic studies?

A

rRNA - universal presence in all cells, same function in all cells
SSU = small subunit
SSU rRNA - referred to as a “molecular chronometer”; sequence changes very slowly due to functional constraints on the molecule

Random mutations on the small SSU rRNA often have serious negative results, so relatively few changes are passed on
rRNA genes’ overall mutation rates also seem similar between species
- Therefore sequence differences can be quantified between SSU rRNA in diff species to infer relationships

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2
Q

Microbiology

A

study of microbes, examines microbial interaction, disciplinary basis for molecular biology and biotechnology

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3
Q

microbe vs microorganism

A

microorganism = archaea, eukaryotes, bacteria

microbes = viruses, archaea, eukaryotes, bacteria

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4
Q

microorganisms for eukarya include:

A

algae
fungi
protozoa

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5
Q

Robert Hooke

A

early microscopes!
first description of microbes (fruiting structures of “moulds”)

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6
Q

Robert’s Hooke’s early microscope structure

A

compound microscope with two lenses:
one bottom one top

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7
Q

Antonie van Leeuwenhoek

A
  • improvements in lens construction allowed first description of bacteria
  • “Father of Microbiology”
  • first to observe moving bacteria “little animalcules”
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8
Q

____ were first life on earth

A

microorganisms

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9
Q

microorganisms established ___ conditions (___) –> led to ____ organisms

A

biosphere
(O2)
multicellularm

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10
Q

microorganisms = >___% earth biomass

A

> 50%

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11
Q

How can microbes help in biogeochemical cycling?

A

interact with environment (cycle inorganic molecules to organic molecules and back, e.g., nitrogen-fixing)

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12
Q

Core features of life!

A
  • metabolism
  • growth
  • reproduction
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13
Q

core features of life achieved by (3)

A

genetic variation/evolution
response/adaptation
homeostasis

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14
Q

how do microbes get energy?

A

heterotroph - ingests preformed organic molecules
autotroph - produces organic molecules
fermentation (less ATP)
aerobic respiration (more ATP)

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15
Q

macromolecules in microbial cells

A

mostly polypeptides (~50%)
then RNA (~15%)
lipids (10%)
sugars (~6%)
DNA (~2-5%)

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16
Q

phylogenetic tree divided into:

A

bacteria
archaea
eukarya

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17
Q

phylogenetic tree is based on ________

A

ribosomal RNA (rRNA)

18
Q

viruses characteristics

A
  • don’t replicate outside of host cell
  • little to no biochemical activity outside of host cell
  • inert and nonreactive outside of host cell
19
Q

Origin of life - early conditions

A
  • little O2 in atmosphere
  • high temp
  • high CO2
  • planet surface was chemical soup with reducing atmosphere (a lot of electrons available to give, e.g., CH4, NH3, H2)
  • initial synthesis of first macromolecules
20
Q

origin of life early conditions - planet surface

A

chemical soup with reducing atmosphere (a lot of electrons available to give, e.g., CH4, NH3, H2)

21
Q

Stanley Miller with Harold Urey

A

simulated “spark” that may have started forming organic molecules from primordial soup
- primitive ocean mixture, cloud formation, primitive atmosphere, electrical sparks (lightning)
- a lot of reducing gases

22
Q

requirements of early life

A
  • genetic information storage
  • ability to catalyze biochemical rxns
  • a way of separating cell interior from external environment
23
Q

ribozymes

A
  • RNA behaving like enzymes (excises portion of rRNA)
  • rxn catalyst
  • genetic information storage
  • self-replicating
24
Q

micelles

A
  • may have been early form of plasma membrane
  • instead of bilayer, just non-polar tails together in globule with polar heads outside
25
Q

RNA world

A

prior to last universal common ancestor (LUCA) which uses DNA
- conceived by Carl Woese (came up with archaea, proposed RNA world)

26
Q

Double-stranded DNA

A
  • provides a “backup” copy of genetic info
  • more stable than RNA
27
Q

LUCA’s likely features

A
  • membrane-bound
  • ATP as chemical energy
  • DNA -> RNA -> protein
  • eats CO2 (autotroph)
  • fixes N2 into NH3
  • anaerobe
  • thermophile
  • burns H2 for electrons/metabolism (found in hydrothermal vents)
  • most likely: autotroph and H2 oxidizer
28
Q

how to circumvent the scarcity of readily oxidized electron donors away from hydrothermal vents?

A

ancestors of cyanobacteria solved this by producing O2 as a toxic byproduct (oxidize water with light energy, reduce CO2 (electron acceptor in photosynthesis))

29
Q

electron acceptor in photosynthesis

A

CO2

30
Q

microbial fossil records exist in ___

A

stromatolites (carbonate pedestals with photosynthetic microbial mat on top)

31
Q

modern DNA processes

A
  • DNA is transcribed into mRNA (transcription)
  • mRNA is translated into proteins (translation)
32
Q

RNA’s other forms (not mRNA)

A

transfer RNA - tRNA
ribosomal RNA - rRNA

33
Q

examine microbial genomes from 2 diff perspectives

A
  1. examine effects of single mutations in DNA individually
  2. study and compare pieces of genome to each other across domains (phylogeny)
34
Q

origin of eukaryotes

A
  • endosymbiotic theory
  • primitive prokaryotic microbes ingested other microbes, starting a symbiotic relationship, forming the first basic eukaryotes
35
Q

microbes and disease

A

microbes not always associated with disease
- historically believed to be bad air, angry gods
- when microbes were discovered, people thought they could spontaneously form from matter

36
Q

Louis Pasteur

A
  • discovered that living organisms discriminate between optical isomers
  • explained biological nature of alcoholic fermentation
  • developed vaccines for anthrax, fowl cholera, rabies
  • developed pasteurization
  • introduced sanitization in hospitals
  • DISPROVED spontaneous generation (think sterile broth)! and developed methods for controlling growth
37
Q

Robert Koch

A
  • determined Bacillus anthracis was cause of anthrax and Mycobacterium was cause of tuberculosis
  • established basic rules for determining which microbes caused which diseases (Koch postulates)
38
Q

Koch’s postulates

A

can be used to show a specific microbe causes a specific disease!
- suspected microbe is identified in every host with disease and not those without disease
- a pure culture of suspected microbe is obtained
- experimental inoculation of suspected microbe into a healthy test host causes same disease
- suspected microbe is recovered from experimentally inoculated host organism

39
Q

gastric ulcers

A
  • sores on stomach lining, thought to be caused by excess acid
  • Helicobacter pylori were isolated from ulcerated tissue
  • by applying Koch’s postulates, this microbe found to cause stomach ulcers
40
Q

microbe-linked disease (just 3)

A

bubonic plague “black death”
smallpox
spanish flu

41
Q

preventions of infection

A
  • antiseptics
  • sanitation improvements
  • food/water safety
  • personal hygiene
  • vaccination
  • antibiotics

BIOL 240 Microbiology (10 decks)

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