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28 Cards in this Set
- Front
- Back
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Parasitism
Commensalism Mutualism |
1) One member in the relationship isharmed, and the other benefits
2) One species benefits, and the otheris neither harmed nor helped 3) Both benefit |
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Chlorochromatium aggregatum
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Consist of green sulfur bacteria (called epibionts) and a flagellated rod-shaped bacterium
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How has molecular methods influenced our understanding of this consortia?
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- Electronmicrographs of consortium reveal intimate contact between epibiont and centralbacterium
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Legume - Root Nodule
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- Savefertilizer expenses and minimizes polluting effects of fertilizers
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Taxonomic groups of Rhizobia
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- Alphaproteobacteria
- Betaproteobacteria
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Leghrmoglobin
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- Leghemoglobin function as an O2-buffer by cycling between oxidized(Fe3+) and oxidized (Fe2+) to minimize unbound O2 withinthe nodules
- Leghemoglobin alsotransport O2 |
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Infection of Rhizobia and formation of root nodules
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Infection:
•Rhizobia produce a cellulosic tube (i.e. infectionthread) to infect the root hair •Rhizobia divide into swollen cells (i.e. bacteroids) •Microcolonies of rhizobiaget surrounded by plant cytoplasmic and form a symbiosome |
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Azolla-cyanobacteria symbiosis
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- Usedfor centuries to enrich rice paddies
- Thewater fern Azolla contains a species of heterocystousnitrogen-fixing cyanobacteria (Anabaena) |
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Alnus-Frankia Symbiosis
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- Thealder tree (genus Alnus) has nitrogen-fixing bacteria and allowsit to colonize nutrient-poor soil
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What are two common plant diseases caused by genes carried on bacterial plasmids?
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- Agrobacteriumtumefaciens -> crown gall disease - Rhizobiumradiobacter -> hairy root disease |
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How are these genes transferred from bacteria to plant?
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Transferred DNA (T-DNA) carries the genes for tumorformation
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How can we use this plasmid for genetic engineering of plants?
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TheTi plasmid has been used in the genetic engineering of plants to introduce DNA into plants and create transgenic plants
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Mycorrhizae
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- Mycorrhizalfungi assist plants
- Improve nutrient absorption |
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Ectomycorrhizae vs Endomycorrhizae
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Ectomycorrhizae
•Fungal cells form an extensivesheath around the outside of the root with only a little penetration into theroot tissue •Found primarily in forest trees,particularly boreal and temperate forests •Trees can form multiple mycorrhizal associations •Endomycorrhizae •Fungal mycelium becomes deeplyembedded within the root tissue •Most are arbuscularmycorrhizae (AM) and penetrates the cortical cellsof the plant roots •Are more common thanectomycorrhizae•Found in >80% of terrestrialplant species•Many are obligate plant mutualists |
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Differentfeeding strategies
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•Herbivores – animals that consume plants
•Carnivores – animals that consume meat •Omnivores – animals that consume both |
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Ruminants and what makes the rumen such a good bioreactor
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•Successful group of foregut fermenters
•Herbivorous mammals (e.g., cows,sheep, goats) •Possess a special digestive organ(the rumen) |
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Biochemical reactions in the rumen
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- Fermentationin the rumen is mediated by cellulolytic microbes that hydrolyze cellulose tofree glucose
- Glucoseis thenfermented, producing volatile fatty acids and CH4 and CO2 - H2consumed by methanogens for the reduction of CO2 -> CH4 - Fatty acidspass through rumen wall into bloodstream and are oxidized by theanimal as its main energy source |
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What is happening in the digestive system of the livestock that causes grain poisoning and why does a gradual shift in diet avoid this problem?
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If it is an abrupt change in diet, it can cause illness. Streptococcus bacteria grows rapidly in the rumen and it can dominate the rumen microbial community. This occurs because cellulose does not support growth of S. , while grains contains high levels of starch, on which S. growths rapidly. Since S. is a lactic acid bacterium, it acidifies the rumen below its lower functional limits (pH 5.5) therefore, disrupting normal rumen activity
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Human micro biome in the GI tract / Benefits
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•Allsites on a human that contains microorganisms are part of microbiome
•Largeintestine most heavily colonized part of the GI Humangut microorganisms produce: •Enzymes (digesting/processing ofcomplex carbohydrates) •Amino acids synthesis |
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Correlation between obesity and microbial community
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- Obesityresults in many metabolic diseases
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Ecto- VS endo- symbionts
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- Ectosymbionts (onsurface or in digestive tracts)
- Endosymbionts (intracellular) |
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Vertical vs horizontal transmission
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•Environmental reservoir (horizontaltransmission)
•Parent (vertical or heritabletransmission) |
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Primary vs secondary symbionts
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- Primarysymbionts are required for host reproduction
- Secondarysymbionts •Not required for reproduction •Not always present in everyindividual •Can invade different cells and liveextracellularly •Must provide a benefit: •Nutritional •Protection from environment Protection from pathogens (e.g.toxin production |
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Termites
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- Termitesdecompose cellulose and hemicellulose using symbiotic protistsand bacteria
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Variation of gut in termites
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Termitegut consists of foregut, midgut, and hindgut
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Bobtail squid
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•Amutualistic symbiosis between the marine bacterium Aliivibrio fischeri and the Hawaiian bobtail squid is a modelfor how animal–bacterial symbioses are established
•Cultivable bacteria (non-obligatesymbiosis)•Single species with sequencedgenome |
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Leeches
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Areparasitic annelids (segmented worms)
•Feed on vertebrate blood andsecrete anticoagulants and vasodilators (used in medical practice in surgery) |
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Coral Bleaching
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- Loss of color caused by lysis ofsymbiont
- High temperature and high lightimpair the photosynthetic apparatus of dinoflagellate |
