L1 - Introduction Flashcards
Origins of microbial life: What were the conditions on Earth when it first formed?
- Sterile, high radiation, and abundant gases
- No life present
Origins of microbial life: When did cellular life first appear, and what were the conditions?
- No oxygen, abundant CO2 and nitrogen.
- Anaerobic microbes thrived, using chemical compounds for metabolism.
Origins of microbial life: What are anoxygenic phototrophic bacteria?
Anaerobic microbes that used light for energy (phototrophic).
Precursors to photosynthesis.
Origins of microbial life: What role did cyanobacteria play in Earth’s history?
- Photosynthetic microbes that used sunlight for energy.
- Released oxygen as a byproduct, leading to Earth’s oxygenation.
- Formed symbiotic relationships (e.g., chloroplasts in plants).
Origins of microbial life: How did modern eukaryotes change the microbial world?
- Enabled aerobic metabolism and multicellular life.
- Stabilized oxygen levels in the environment.
Origins of microbial life: What evolutionary steps followed the appearance of eukaryotes?
- Diversity of photosynthetic algae.
- Evolution of shelly invertebrates → vascular plants → mammals → humans.
How were we able to determine the tree of life? What about in microorganisms?
how do we know that? - fossils, physical structures, skeletons. in microorganisms we use rRNA sequencing
What methods are used to study microorganisms and their evolution?
- DNA sequencing: Analyzing chemical structures in genetic material.
- SNPs: Single Nucleotide Polymorphisms.
- Gene changes: Studying gene loss, acquisition, and mutations.
- Genetic analysis: Identifies relationships between organisms.
What properties should genes have to study evolution?
- present in all organisms
- should be conserved
- slow-changing so not lost/gained in multiple copies, should have same function
What are the 3 domains of the tree of life and what is the intermediate
Bacteria, archaea, eukarya
- archaea is the intermediate, single cells but mechanisms for DNA replication and protein synthesis are like eukaryotes
What is LUCA? What diverged first and then what diverged?
Last universal common ancestor
- first divergence was bacteria
- archeae diversified to eukaryotes
How did the updated tree of life group the classes
bacteria & archaea (eukarya as a subset of archaea)
where are most of the microbial cells on earth?
marine subsurface (very few in soil)
Why are microbial cells key reservoirs of essential nutrients for life?
- account for a lot of the biomass
- they account for 80% of nitrogen and phosphorus in the planet (essential for DNA/RNA/proteins
List 6 resources and outline 6 conditions that govern microbial growth
resources: carbon, nitrogen, macronutrients, micronutrients, oxygen, inorganic e- donors
conditions: temp, water potential, ph, oxygen, light, osmotic
in terms of temp, list the name of microbial cells from cold -> warm -> hot
psychrophile mesophile thermophile
in terms of pH, list the name of microbial cells from 0->7->14
acidophile, neutralophile, alkaliphile
What are extremophiles and where do they live?
- an organism that is able to survive (and possibly thrive) in environments made challenging due to extreme temperature, pH, salinity, pressure, etc.
- environment way too extreme for us but normal for them (human central definiton)
What are the key conditions of the deep ocean?
Depth: 6.8 miles (Mariana Trench).
Pressure: 8 tons per square inch.
Salinity: Constant at 3.2% below 300 m.
Light: No surface light; some from hydrothermal vents.
Temperature: 1–3°C, invariant; some areas always frozen.
What are hydrothermal vents, and what are their characteristics?
Hot springs at the ocean floor (<450°C).
High temperature, high pressure, and toxic compounds.
pH: Very acidic (pH <3) or alkaline (pH ~11).
Carbon source: Organic matter, carcasses, and detritus.
What are black smokers and white smokers?
Black smokers: Rich in iron sulfites (acidic).
White smokers: Rich in calcium and silica (alkaline).
How do chemosynthetic bacteria support life?
Convert heat, methane, and sulfur into energy.
Use dissolved chemicals and heat as energy sources.
Grow in mats that support other life forms.
What are natural extremophile environments?
- Salt lakes: Cyanobacteria thrive after water evaporates.
- Soda lakes: Red due to haloarchaea.
- Desert soils.
- Hot springs with extreme conditions.
What are man-made extremophile environments?
- Mines: Surface and underground.
- Dams.
- Deserts: Caused by deforestation.
- Mining side effects: Rivers turned yellow, supporting archaea.
