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40 Cards in this Set
- Front
- Back
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Ecosystem
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The sum total of all organisms and abiotic factors in a particular environment interacting as a system
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Habitat
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Portion of an ecosystem where a community could reside
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Niche
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Habitat shared by a guild. Supplies nutrients as well as conditions for growths
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Guilds
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Sets of guilds from microbial communities that interact with microorganisms and abiotic factors in the ecosystem
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Community
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Consists of populations of one species living in association with populations of one or more species.
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Species richness
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Total # of different species present
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Species abundance
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Proportion of each species in an ecosystem
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Population
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- Microbial communities consist of populations of cells of different species
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Availability of resources
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- Growth of microbes depends on the available resources and growth conditions
- Differences in the type and quantity of resources and the physiological conditions of a habitat define the niche for each microbe - Resources in natural environment are highly variable, and many microbes in nature face a feast - or - famine existence |
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Microenvironment
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- The immediate environmental surrounding of a microbial cell or group of cell
- Soil particles contain many microenvironments |
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Prime niche
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One niche that organisms is most successful
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Fundamental niche
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The full range of environmental conditions under which an organism can exist
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Slower growth rates in nature than in lab. Why?
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Because:
1) Resources and growth conditions are frequently suboptimal 2) The distribution of nutrients throughout the microbial habitat is not uniform 3) Microorganism in nature grow in mixed populations rather than pure culture |
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What are some of the benefits for microbes to form biofilm?
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- Biofilms trap nutrients for microbial growth and help prevent detachment of cells in flowing systems. It serves as self defense and resist physical forces
- Allow cell to remain in niche - Allow cells to live closer to one another |
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What are surfaces beneficial for many microbes?
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- Because nutrients absorb to surfaces
- Microbial cells can attach to surfaces |
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Why is biofilm formation important to humans?
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- Medicine and Dental
- Can slow the flow of liquid though pipelines - Can accelerate decay of sluggish surfaces |
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How do microbes form and coordinate biofilm formation?
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- It is initiated by an attachment of cells to a surface, followed by the expression of biofilm-specific genes
- These genes encode proteins that synthesize intercellular signaling molecules and initiate matrix formation |
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Quorum sensing
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Critical in the development of biofilm because it gets the right amount of genes it needs to of the job.
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What makes microbial mats different from biofilm?
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- They are thick biofilms
- Built by phototrophic and cyanobacteira |
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Phototrophic and chemolitotrophic mats
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- Phototrophic contains filamentous cyanobacteria
- Chemolitotrophic contain filamentous sulfur-oxidizing bacteria |
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Availability of resources
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- Availability of water is the most important influencing microbial activity in surface soils
- Nutrient availability is the most important factor in subsurface environments |
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Principles behind phylogenetic sampling
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Molecular sampling indicates thousands o different microbial species
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What is a phylotype?
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A "species" defined by 16R rRNA sequence that differs from all other sequences by 3%
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How does soil surfaces form a soil subsurface?
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- Soil subsurface can extent for several hundred meters below the soil surface
- Microorganisms in the deep have access to nutrients because groundwater flows through their habitat - Archea and Bacteria are believed to exists in deep subsurface |
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Balance between photosynthesis and soil surface
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Controls the oxygen and carbon cyles
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Phytoplankton vs. benthic species
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- Phytoplankton: oxygenic phototrophs suspended freely in water; include algae and cyanobacteria
- Benthic species: attached to the bottom or sides of a lake or stream. |
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Why is mixing important in freshwater environment?
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- Mixing is important because the oxygen concentration in aquatic systems are dependent on the matter present and the mixing
-Due to rapid flow, rivers are mixed well. |
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Biochemical oxygen demand (BOD)
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The microbial oxygen consuming capacity of a body of water
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How are rivers similar/different from lakes?
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Lakes: -In lakes, the water column becomes stratified during the summer- High microbial diversity Rivers: - Suffer from oxygen deficiencies because of high inputs of organic matter of sewage and agricultural and industrial pollution |
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What effect can nutrient release have on aquatic environments?
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Theactivity of heterotrophic microbes in aquatic systems is highly dependent uponactivity of primary producers; oxygenic phototrophs produce organic materialand oxygen
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Nutrient levels in marine environments
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Marine environment is :
- Saline - Low nutrients, especially with respect to oxygen, phosphorus and iron.- Cooler |
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Oxygen Minimun Zones
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- Regions of Oxygen depleted waters at intermediate depths
- High oxygen demand - Nutrient rich areas - High levels of denitrification and anammox - Expanding |
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Primary Production
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Most of primary productivity in the open ocean is due to photosynthesis by prochlorophytes.
Primary producers synthesize new organic matter from CO2. |
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Why are phototrophic microbes so important in the ocean?
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Small phototrophic eukaryotes, such as Ostreococcus, inhabit coastal and marine waters and are likely important primary producers.
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What are some of the major groups of primary producers in marine environments?
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- Microorganisms - Phototrophs - Cyanobacteria - Autotrophs |
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What are the proportions of Bacteria, Arhcea and Viruses in the ocean?
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Viral concentration is believed to be as high as 10^8 iron particles per mL
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How does the abundance of Bacteria, Archea, and Viruses differ in depth?
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Abundance in the open ocean decreases with depth
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How do viral and prokaryotic populations affect each other?
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Virus infections probably help maintain prokaryotic numbers at the level that are observed.
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Which are the most abundant bacteria in the ocean and what makes them so successful?
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Viruses are the most abundant microorganisms in the ocean.
- Alpha and Gammaproteobacteria, cyanobacteria, bacetreodetes. |
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Are any microbial groups unique for the ocean?
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Theplanktonic filamentous cyanobacterium
Trichodesmium is an abundant phototroph in tropicaland subtropical oceans |
