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Microbes exam 4 pt 2

Terms in this set (37)

What is symbiosis?
organisms of two different species living in a close relationship
What is mutualism?
symbiotic relationship in which both species benefit from the relationship
What is commensalism?
symbiotic relationship in which one organism benefits and the other is neither helped nor harmed
What is parasitism?
symbiotic relationship in which one organism (the parasite) benefits and the other organism (the host) is harmed
What is endosymbiosis?
symbiosis in which one of the symbiotic organisms lives inside the other.
Describe the symbiotic relationship between European beewolf + Streptomycetes
Mutualistic bacterial symbiosis; bacteria grows on the antennae of the beewolf and inoculates the egg den for larvae protection. This protects against 9 different antimicrobials.
Describe the symbiotic relationship between leaf cutter ants and Streptomycetes
Mutualistic bacterial symbiosis; bacteria grows on the exoskeleton on the ants and forms a white, powdery substance that protects the ants from a wet fungus that grows in their habitats.
Describe the symbiotic relationship between squid and Vibrio fisheri
Mutualistic bacterial symbiosis; chemiluminescent bacteria provide camouflage to the squid
Describe the symbiotic relationship between soil nematodes and Photorhabdus luminescens
Mutualistic bacterial symbiosis; soil nematodes are a worm that lives in the ground... relationship kills and attracts insects.
Describe 4 examples of deep sea symbiotic relationships.
1. Yeti crabs that grow gardens of bacteria
2. Riftia tube worm... 1st organism identified to have a chemoautotrophic symbiont
3. Mussels and giant clams have bacteria in their gills
4. The Pompeii worm: worm secretes mucus to feed bacteria covering its body... sulfur- and methane- oxidizing bacteria act as insulation and food for worm
Describe the symbiotic relationship between fungi and cyanobacteria/algae. What is lichen?
Mutualistic fungal symbiosis; fungus benefits from the carbohydrates produced by the algae and the algae benefits from the environmental protection provided by the fungus. A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.
Describe the symbiotic relationship between plants + Glomeromycota (mycorrhizae)
Mutualistic fungal symbiosis; plants provide sugars for the fungus and fungus provides phosphorous and other minerals... they need each other to live
Describe the symbiotic relationship between scale insects + Septobasidial fungi:
Mutualistic fungal symbiosis; fungus forms elaborate structures over insect colonies feeding on bark, insect sinks proboscis into bark and remains there sucking sap the rest of its life, fungus feeds on insects without killing them parasitized insects are rendered sterile, perpetuation of insect species and fungal spread are accomplished by uninfected members of colony... protected from enemies by fungus body
Describe the symbiotic relationship between the ambrosia beetle and Ascomycetes
Mutualistic fungal relationship; adult insect carries fungi in mycangia (deep pockets in outer cuticle of body) ... eggs are deposited with fungi into holes bored into timber
What is zooxanthellae?
A photosynthetic algae (Protozoan)... dinoflagellates live within tissues of jelly fish, corals, sea slugs, and other marine invertebrates. This is a symbiotic relationship.
What role do lower termites and flagellates, as well as ruminants + ciliates play in symbiosis?
They are all Protozoan that aid in digestion in some way.
What is conditional mutualism and how does it relate to viral symbiosis?
Plants have a symbiotic relationship with many beneficial viruses. They can alleviate plant "stress" and the isolation of these types of viruses can play an important role in agriculture. Ecological forces that cause a mutualism to vary in space and in time is termed "conditional mutualism"
Describe the symbiotic relationship between Cotton Bollworms + Helicoverpa armigera densovirus.
Viral symbiosis; increases developmental rate and life span of both larvae and pupa. Also increases the resistance to a biopesticide.
Describe the symbiotic relationship between Rosy apple aphid + Densovirus:
virus causes development of winged aphids and virus remains at low levels but infection increases with overcrowding.
Describe the symbiotic relationship between Tomato and thrips + Tomato spotted wilt virus:
virus suppresses "antifeeding" compounds
Describe the symbiotic relationship between humans and Hepatitis G virus.
Viral conditional mutualism; HIV-positive patients show slower disease progression and in vitro studies suggest down-regulation of cell receptors for HIV entry, reduced HIV replication, and interaction with interleukin pathways and interferon synthesis
Describe the symbiotic relationship between mice and gamma-herpes virus.
increases resistance to Listeria monocytogenes and
Yersinia pestis
What is symbiogenesis?
The origin of new tissues, organisms, organs and even species by the establishment of long term or permanent symbiosis. This happens when endosymbionts become part of the larger organism.
What are Human Endogenous Retroviruses (HERVs)?
Retroviruses that infect egg or sperm cells are called human endogenous retroviruses (HERVs) ... viral DNA is passed down through generations
What are the steps of HERVs?
1. Fusion with cell
2. Inject RNA + Reverse Transcriptase (RT)
3. RT converts DNA to viral cDNA (copy DNA)
4. RT makes cDNA double-stranded
5. Another enzyme carries viral DNA into the nucleus
6. host genome is nicked and viral DNA is integrated
What is syncytin (SYN)?
A gene that codes for a protein and is only expressed in barrier layer of cells between maternal uterine wall and fetal placenta. This gene is an ancient HERV. Syncytin 2: viral protein suppresses mother's immune system so it won't reject or attack fetal tissues.
What role do HERVs play in early embryonic development?
In the early stages, specific groups of HERVs are transcribed before embryo has implanted. The number of HERV proteins peak at 4-cell stage.
What symbiotic relationships do biofilms have with the human body?
They are irreversibly associated with certain structures in the human body, like plaque on teeth... channels form to deliver nutrients to certain areas.
What are "model organisms" and what are the benefits of using microbes as model organisms?
A model organism is something that is studied extensively to understand a specific phenomenon while generalizing it to other organisms as well. Microbes make great model organisms because there are no ethical concerns with using them, they can reproduce and grow very rapidly, they survive in a variety of different conditions, and they can be harmless when handled correctly.
Why do we use Bacteriophage as model organisms?
We can study control of lytic and lysogenic replication, regulation of operons, DNA virus assembly, genomic library...
What is cell signaling?
communication between cells using chemical messengers; important for maintaining homeostasis
What is N. crassa and why do we use it as a model organism?
It is bread mold and we use it to study meiosis and circadian rhythms, since spores live on a 24 hr. cycle.
What is Dictyostelium discoideum and why do we study it as a model organism?
It is a slime mold that exists as separate amoebae, but they can stream together to form a multicellular organism.
What are the goals of the National Microbe Initiative (NMI)?
1. To support research to answer fundamental questions about microbiomes that exist in different ecosystems.
2. To develop platform technologies to share insight into microbiomes.
3. To expand the microbiome workforce.
What is the Microbiota-Gut-Brain Axis?
signaling between enteric nervous system in gut & brain ... starting to be better understood
What are short-chain fatty acids and what relationship do they have to different diets?
These acids influence transcription of genes. The Western diet actually suppresses the production of these acids. In a study where mice were med a Mediterranean diet, there was an increase in the production of these acids.
What happens when probiotics are introduced into the diet of a depressed person?
Symptoms of depression decreased.
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