Lecture 20: Microbial Systematics and Diversity Flashcards Preview

BIO 425: Microbiology > Lecture 20: Microbial Systematics and Diversity > Flashcards

Flashcards in Lecture 20: Microbial Systematics and Diversity Deck (35)
Loading flashcards...

What is the era of heavy bombardment?

First 500 Million Years of Earth

No Evidence of Life
-­Temperatures Too High
-­Intense UV Radiation
-­Collisions With Asteroids/Rocks

Water On Earth
-­Collisions With Icy Comets


How did the formation of a hospitable earth occur?

End of era of heavy bombardment cause temp decrease

Geological and Ocean Development


What is the subsurface hypothesis for the origin of life?

First life evolved in hydrothermal vents
-warm water w/ lots of nutrients
-No UV radiation
-stable temperature


What is the early evidence of cellular life?

-­Layered Mixtures of Microbes – “Microbial Mats”
-­Trap Mineral Materials – Fossilize

Microbial Fossils

Microbial Forms Preserved In Ancient Rock


How long ago did microbial life first appear? What conditions were compatible w/ life?

At least 3.5 Billion years ago

-Liquid water
-Temp (0-100 degrees)
-Anoxic atmosphere


What were the early types of microbial metabolism?

Anaerobic and Autotrophic b/c
-anoxic ocean and atmosphere
-mostly inorganic chemicals present


What were the early metabolism types that used light energy?

Phototrophy (Anoxygenic)
-­Energy Source = Sun
-­Electron Donor = Hydrogen Sulfide (H2S)
-­Carbon Source = CO2

Phototrophy (Oxygenic)
-­Energy Source = Sun
-­Electron Donor = Water (H2O)
-­Carbon Source = CO2


What is the chemical reactions for oxygenic and anoxygenic phototrophy?

Phototrophy (Anoxygenic)
Inorganic Carbon + H2S + Light -> Organic Carbon +
Elemental Sulfur

Phototrophy (Oxygenic)
Inorganic Carbon + H2O + Light -> Organic Carbon +
Oxygen (O2)


What is the great oxidation event?

2.5 billion years ago where atmosphere gets O2

Aerobic Respiration Possible
-Major Pathway of Most Life On Earth Today

Formation of the Ozone (O3) Layer
-Barrier to Ultraviolet Radiation from the Sun


What took so long for the great oxidation event to occur?

Cyanobacteria Produced Oxygen For 500 Million Years Before Change In Atmosphere
-­Oxygen Consumed By Iron Minerals in the Ocean
-­Iron Oxidation: Ferrous (Fe2+) -> Ferric (Fe3+)


How is endosymbiosis significant to eukaryotes and plants?

Free living bacteria made their way into eukaryotes/plants

Chloroplast = cyanobacteria
Mitochondria = proteobacteria


What are the characteristics of mitochondria and chloroplasts?

-­Contain Their Own DNA
-­Have Circular DNA (like prokaryotes)
-­Have Small Ribosomes (70S) (like prokaryotes)


How do mitochondria and chloroplasts produce energy?

Mitochondria -> Consume O2 -> Energy

Chloroplast -> Produce O2 -> Energy from Sun


What are the unifying features of domain archaea?

Traits Shared by All Archaea
-Ether-­‐Linked Lipids
-Lack of Peptidoglycan
-Complex RNA Polymerases


What traits are only found in domain archea?

-Conserving energy from the production of methane

Life in Extreme Heat
-­Only organisms in environments >100˚C


What kinds of habitats are archaea found in?

Extreme cold or heat
-antarctic sea ice, volcanic hot springs, hydrothermal vents

Extreme salinity
-Salt lakes and salterns


What are the only gram-positive bacteria?

Actinobacteria, Firmicutes, and Mollicutes


How many culture strains and uncultured strains of bacteria?

Culture Strains ~18 phyla
Uncultured Strains >80 phyla


What are the ancient bacterial phyla that are hyperthermophiles?

-Most Heat Tolerant (95°C)
-Aerobic Hyperthermophile

-Anaerobic Hyperthermophile
-20% of Genes from Archaea

-Ether-­‐Linkage Lipids


What is Deinococcus-Thermus?

Genus Thermus
-­T. aquaticus -> Taq Enzyme

Genus Deinococcus
-­D. radiodurans
-Soil and Dust Particles
-Survives Intense Radiation (15,000 grays; 10 kills humans)
-Resistant to Mutagenic Compounds


What are Deinococcus radiodurans used for?

DNA Repair Enzymes
-Single or Double-­‐Stranded Breaks
-­Repair Misincorporated Bases

DNA Arrangement
-­Cells Always in Pairs
-­DNA Stored in Nucleoids
-­Repair By Nucleoid Fusion


What are spirochetes?

Motile, Tightly-­‐Coiled Bacteria
-Rare Example of Morphology Predicting Phylogeny
-Common in Aquatic Habitats and Animal Hosts

Contain Endoflagella
-Remain in Periplasm of the Cell
-­Rotation Provides Torque Motility


What kinds of spirochetes are pathogens?

Treponema allidum = Syphilis

Borrelia burgdorferi = Lyme Disease


What is the Genus Bacteriodetes?

Common in Intestinal Tract of Animals
-Most Common Species in Human Gut
-­Break Down Polysaccharides (plant matter)


What are some familiar proteobacteria?

Genus Escherichia
-Intestinal Tract of Animals, Some Pathogenic

Genus Salmonella
-Closely Related to Esherichia,
-Most Pathogenic

Genus Vibrio
-V. chloerae ·∙

Genus Aliivibrio
-A. fisherii ·∙


What are some unique proteobacteria?

Magnetic Bacteria
-Magnetosprillum magnetotacticum
-Contains Iron Minerals in Magnetosomes
-Detect and Respond to Magnetic Fields

Predatory Bacteria
-Bdellovibrio spp.
-“Bdello” = Leech
-Prey on Other Bacteria


What are some non-endospore forming genera of firmicutes?

Genus Staphylococcus

Genus Streptococcus
-­Dental caries

Genus Listeria
-­Food infection

Genus Lactobacillus
-­Lactic Acid Bacteria


What are some endospore forming genera of firmicutes?

Genus Bacillus
-B. anthracis = Biological Weapon
-­B. thuringiensis = Bt Toxin
-­B. subtilis = Host Cell

Genus Clostridium
-­C. botulinum = Botulism
-­C. tetani = Tetanus


What are some general features of actinobacteria?

Rod shaped or filamentous
Primarily aerobic and found in soil

Notable Pathogens = mycobacteria
Antibiotic producers = streptomyces


What is microbial taxonomy?

Identifying, classifying and naming Microorganisms
-historically based on phenotypes
-now based on metabolism, physiology, chemical characteristics