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LSCI 230 - Final
| Question | Answer |
|---|---|
| What are the two names assigned to organisms in their nomenclature? | genus and species / generic and specific |
| What are the two methods of classification used in taxonomy of bacteria/archea? What are these methods based on? | Phenetic (similarities in characteristics) and Phylogenetic (evolutionary relationships/ancestry) |
| What defines a species? | Two organisms within the species can interbreed to produce fertile offspring that can also interbreed |
| Describe the oldest microorganisms known to man | stromatolites ~3.5 byo ancient ones were anoxygenic, phototrophic modern ones are oxygenic phototrophic lived in communities that produced biofilm, mineral deposition |
| Describe the surface origin hypothesis and why it was rejected | first form of life originated from "primordial soup" of organic and inorganic material - improbable because of the plethora of perpetual extreme natural disasters |
| BRIEFLY describe the subsurface origin hypothesis | Life originated in hydrothermal springs on ocean floor more probable than surface origin theory because more stable conditions with lots of energy substrates available |
| Describe how life would have come about if following the subsurface origin theory | water from ocean penetrated ocean crust and was heated then expelled into chambers within hydrothermal mounds on ocean floor. eventually, conjugation of organic compounds formed RNA molecules |
| Provide 2 reasons why RNA was an optimal origin of cellular life | it can store genetic information that can be copied it has a catalytic function it can bind small molecules |
| What kind of energy metabolism characterized primitive cells? | anaerobic, chemoautotrophic |
| Carbon source of primitive cells? Energy and electron sources? | CO2; H2 (from H2S and FeS in hydrothermal mounds) |
| 1-4 list in order of their appearance on Earth types of bacteria based on their metabolism | 1. chemolithotrophic 2. anoxygenic photosynthetic 3. oxygenic photosynthetic 4. chemoorganotrophic |
| Why did anoxygenic photosythesis predate oxygenic photosynthesis? | Because it was simpler in mechanism |
| Describe the principle of numerical taxonomy; what type of classification is it? | characteristic data is gathered on species and assembled. Domains/classifications are then organized based on number of similarities; it is phenetic type of classification |
| Why is numerical taxonomy not conducive to bacterial taxonomy/microorganism taxonomy in general? What is the unit used to express degree of similarity? | Too complex, not feasible to define microorganisms to the extent of animals without use of computerized systems; Jaccard coefficient = coefficient of similarity |
| Briefly describe evolutionary process | accumulation of mutations that are favourably selected by the inhabited environment and eventually leads to speciation |
| What is the method used to phylogenetically classify bacteria/archaea/eukaryotes? | Sequencing of ribosomal RNA: comparing sequencing of SSU conserved and variable regions |
| Describe the 2 theories of endosymbiotic origin of eukaryotes | 1. symbiotic relationship between archaea and bacteria occurs triggering development of a nucleus 2. archaea develop nucleus and then form a symbiotic relationship with ancestors of chloroplast/mitochondria to form eukaryote |
| Why is phylogenetic classification preferred to phenetic classification? | because metabolic properties won't match between classifications: these properties were acquired through HGT, not VGT |
| What makes caulobacter bacteria unique? | ability to differentiate + ability to secrete stickiest substance known to man |
| describe the cell cycle of chlamydia bacteria | Elementary bodies are metabolically inactive, highly resistant; phagocytozed by host cell; conversion to reticulate body that is active in host cell to infect and deplete nutrients; explosion of host cell and release of elementary bodies once again |
| Why is it especially difficult to identify species of microorganisms? | Because they reproduce asexually |
| What is MLST? Briefly describe why it is used | Multilocus sequence typing; genes that code for essential functions and which don't evolve rapidly are useful in classifying species of a genus |
| How are unknown microorganism identified? | By comparison of its properties with those of organisms that have already been classified |
| What is serotyping? | the use of antigen identification as a way to classify or identify microorganisms |
| Secondary endosymbiosis? | product of primary endosymbiosis undergoes another round of it, engulfing the cell to acquire its function. |
| Why is SSU sequencing insufficient in taxonomy of eukaryotes? Solution? | -period of rapid evolution blurring genes -younger than archaea and bacteria = messier sequencing solution: sequence genes of other cell units MLST |
| What gives red algae their pigment? | they produce phycoerythrin |
| What is another name for green algae? | Chlorophytes |
| where do endolithic algae grow? | Inside pores of rocks/layers of sediment |
| What are the two adaptations that amitochondriate eukaryotes have developed? Describe | mitosomes: reduced form of mitchondrion, lack enzymes for TCA cycle hydrogenosomes: present in fermentation and produces substrates for methanogens |
| What are cysts? Function? | differentiated version of the eukaryote that that is metabolically inactive "survival vessel" |
| What is a diplomonad? | eukaryote two nuclei, contain mitosome |
| What is a parabasalid? | eukaryote contain parabasal body, contain hydrogenosome |
| What are the commonalities between parabasalids and diplomonads? | -Lack chloroplast -Unicellular -Flagellated -Anoxygenic habitats |
| What are kinetoplastids? | Euglenozoans that have a kinetoplast |
| what is a kinetoplast? | Mass of DNA present in a single, large mitochondrion |
| Euglena: unique property that allows them to live in a wide variety of conditions? | simultaneously chemoautotrophic and heterotrophic |
| Characteristic property of alveolates? | alveoli that act as water pumps to maintain osmotic balance in cell or as contractile vacuoles |
| which microorganisms are most often involved in food fermentation? | Yeasts (CO2 and EtOH) and lactic acid (reduce pH) |
| Describe lactic acid bacteria | they are gram negative they are aerotolerant reduce food spoilage |
| Difference between homo- and heterofermentative? | homo: use only lactic acid bacteria, goal is to reduce pH hetero: use lactic acid bacteria and flavour compounds |
| which organisms are used to make yogurt? | L. bulgaris and S. thermophilus |
| which organism is responsible for curdling in cheese production? | lactic acid bacteria |
| Name the ripening agents: cheddar Oka blue/Roquefort | cheddar: LA bacteria Oka: geotrichum blue: Peniciliium roquefortii |
| Which organisms are used in the fermentation of wine as to allow for the high alcohol content? | S. cervisiae and S. ellipsoideus |
| Describe the two main steps in production of beer | 1. grains germinate to produce amylase and then dried and crushed (MALTING) 2. Malt is soaked in warm water allowing amylase to break down starch (MASHING) |
| food spoilage? | any deformity or change in appearance or smell that would deter consumer |
| hot foods should be kept above _____ degrees Celsius. cold foods should be kept below ____ degrees Celsius. | 60; 4.5 |
| Main culprit in spoilage of acidic foods? | molds, yeasts |
| what determines the targets of different microorganisms in food contamination? | their enzymatic abilities |
| Food poisoning/intoxication vs. infection? | food poisoning: caused by microbial toxins ingested from the food food infection: caused by the ingestion of pathogen. |
| Which organism causes botulism? | Clostridium botulinum |
| how are C. botulinum bacteria inhibited? | by nitrates/nitrites |
| Most common source of food poisoning? | staphylococcus aureus on epidermis of people handling food & subsequently not following food safety guidelines |
| E. coli infection? | AB-type exotoxin produced and secreted in gut; causes bloody diarrhea and destroys kidney cells (causes HUS) |
| what is the 12D process in canning? | temperature and time of exposure to kill C. botulinum spores |
| disease vs. infection | disease: refers to the damage or injury to host infection: establishment of microorganism in host |
| what are the 2 basic features characterizing virulence? | invasiveness: ability to become established in host toxigenicity: capacity to produce toxins |
| two types of toxins? | endo: part of the bacterial pathogen exo: secreted into the surrounding |
| 5 virulence factors that contribute to invasiveness? | 1. adhesins: surface proteins to attach to host 2. capsule: protective outer shell 3. enzymes: penetration of mucosa/epidermis 4. invasins: surface proteins that trick cell into phagocytozing it 5. T3SS and T4SS: injection of proteins into host cell |
| difference in function between two types of toxins? | exo: proteins destroyed by heat, immunogenic (incl AB toxins: 2 subunits) endo: lipid A of LPS, heat stable, overwhelms immune system |
| toxoid? | inactivated toxin |
| innate vs. adaptive defenses? | innate: normal, non-specific host defenses adaptive: induced by infection, specific to pathogen |
| how is our gut microbiome immunoprotective? | secretion of bacteriocin :antibiotic |
| second line of defenses? | complement system: AMPs induce lysis, MAC (G-) phagocytes: eat pathogens; bring Ag to T-cells |
| general description of B and T cells | B: produce Abs for short term (plasma cells) and long term (memory) immune response T: cytotoxic-kill host cells with foreign Ag; helper cells-activate B-cells |
| Il-1 purpose? | pyrogenic cytokine (fever) that signals inflammation, causing blood vessels to leak WBCs into tissues |
| Il-2? | produced by cytotoxic T cells to induce differentiation, replication of T cells |
| MHC I vs. MHC II: expressed by? recognized by? | MHC I: expressed by all cells; recognized by Tc MHC II: expressed by B cells and APCs; recognized by Th |
| how do helper T cells activate macrophages? | TNF-alpha: heightened response/hyperactivation of adaptive immune system |
| two functions of Abs? | 1. flags macrophages, activates complement system to induce phagocytosis of pathogen 2. binds toxins to sequester them, binds to adhesins to prevent functioning |
| What is the evolutionary adaptation that rabbits have developed to complement their diet insufficiency? | coprophagy: eating their faecal pellets |
| which organism is known to contribute to dental plaque? | Streptococcus mutans: produces polysaccharides that form an ECM |
| How do microorganisms contribute to tooth decay? | The anoxic environment under plaque near the tooth allows for fermentation of incoming sugars which produced lactic acid. This demineralizes the tooth enamel. |
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