MB Test 3 – Microbiology – Flashcards
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| Which technique(s) is/are used to help identify and classify bacteria? |
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| Gram Stain, size, shape, oxygen requirements, biochemical tests, other stains (capsule, endospore, acid fast) |
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| What is the correct order of taxa? |
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| Species, genus, family, order, class, phylum, kingdom, domain. (Dumb King Philip Came Over For Good Soup) |
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| Be able to identify the most inclusive and least inclusive taxa |
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| Inclusive: Domain Exclusive: species |
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| What are the 3 domains according to the new classification scheme? |
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| Bacteria, Archaea, Eukarya. |
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| Why is the 3-domain system accepted? |
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| The system is based on the work of Carl Woese and colleagues who compared the sequences of nucleotide bases in ribosomal RNA from a wide variety of organisms. They showed that prokaryotes could be divided into two major groups that differ from one another as much as they do from the eukaryotic cell. The ribosomal RNA data are consistent with other differences between the Archaea and Bacteria, including the chemical compositions of their cell walls and cytoplasmic membranes. The five kingdom system recognizes the obvious morphological differences between plants and animals, but it does not reflect the recent genetic insights of the ribosomal DNA. |
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| 10. What is the relatedness of organisms determined by counting common characteristics is called? |
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| phylogeny |
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| What is the sequencing of ribosomal RNA is useful for? |
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| Shows the relatedness of all prokaryotes, designates all organisms in one of three domains. Because of their highly constrained and essential function, the nucleotide sequence changes that can occur in the rRNAs, yet still allow the ribosome to operate, are limited. This is why they have proved so useful in microbial classification and, more recently, identification. While earlier methods relied on determining the sequence of the rRNA molecule itself, newer techniques sequence the DNA that encodes rRNA, which is called rDNA. Whichever DNA encodes the rRNA thrown at it in a pile of different DNA, is the right one because the correct choices are so rigid and limited. Instead of guessing which sequence is right, they let it "out" itself. |
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| What is the reference guide for taxonomic descriptions of bacteria called? |
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| Bergey's Manual of Systematic Bacteriology |
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| Know the father of Taxonomy |
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| Carolus Linnaeus |
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| How does sequencing RNA help classification system? |
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| Sequencing RNA is more useful than one that simply groups organisms by arbitrary characteristics, because it is less prone to the bias of human perceptions. It also makes it easier to classify newly recognized organisms and allows scientists to make predictions, such as which genes are likely to be transferred between organisms. The development and application of molecular techniques such as nucleotide sequencing, however, is finally making it possible to determine the genetic relatedness of microorganisms. Can also show the relative time lapse between evolutionary mutations, show horizontal gene transfer as well. |
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| Know the proper way of writing scientific names. |
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| The first word in the name indicates the genus, with the first letter always capitalized, the second indicates the specific epithet or species name and is NOT capitalized. Both words are usually italicized or underlined for example Escherichia coli, the genus name is commonly abbreviated, with the first letter capitalized as in E. coli. |
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| What do modern approaches to evolutionary taxonomy involve? |
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| The three domain systems: bacteria, archaea and eukarya. rRNA sequencing, serology, fatty acid analysis, metabolic capability testing, morphology, |
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| Know different methods used to identify phenotype of prokaryotes. |
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| Microscopic morphology (size and shape, stains) Metabolic Capabilities (culture characteristics, biochemical tests), Serology (characteristic structures in cell that can be found to identify) pH indicator, biochemical test, blood agar, and antigens |
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| What is serology? |
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| Proteins and polysaccharides that make up a prokaryote’s surface are sometimes characteristic enough to be identifying markers. The most useful of these are the molecules that make up surface structures including the cell wall, capsule, flagella, and pili. For example, some species of Streptococcus contain a unique carbohydrate molecule as part of their cell wall that can be used to distinguish them from other species. These carbohydrates, as well as any distinct proteins or polysaccharides, can be detected using techniques that rely on the specificity of interaction between antibodies and antigens. Methods that exploit these interactions are called serological tests. |
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| How morphology of prokaryotes determined? |
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| Size, shape, colony structure and staining characteristics give suggestion, but further testing is needed. |
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| In many biochemical tests, media changes color as a result of the biochemical activity of growing bacteria. Why? |
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| Color change can come about as the result of fermentation, pH indication, motility, or hemolysis. It is the telling sign in a differential media. |
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| What are Serological methods and what is the use for them? Be able to explain examples. |
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| Are used to identify specific bacteria. The most useful of these are the molecules that make up surface structures o cell wall, capsule, flagella, Pilli. For examples: some Streptococcus contain a unique carbohydrate in cell wall, and this distinguishes them form other species. |
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| What is PCR? How can it be used to identify prokaryotes? |
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| Polymerase Chain Reaction is a Nucleic acid amplification tests (NAATs) used to increase number of copies of specific DNA sequences. To use PCR to detect a microbe of interest, a sample is treated to release and denature the DNA. Specific primers and other ingredients are then added. After 30 cycles of PCR, the target DNA will have amplified approx. a billion fold. By selecting primers that amplify a nucleotide sequence unique to a microbe of interest, researchers can apply PCR to determine if a particular agent is present. |
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| What is phage typing? |
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| A bacteriophage, or phage, is a virus that infects and multiplies within bacteria, often lysing them. Each type of phage has a limited host range. Lysis of the infected cell releases more phage particles, which in turn infect neighboring bacterial cells. The susceptibility of an organism to a particular type of phage can be readily demonstrated in the laboratory. First, a culture of the test organism is inoculated into melted, cooled nutrient agar and poured onto the surface of an agar plate, thus creating a uniform layer of cells. Then drops of different types of bacteriophage are carefully placed on the surface of the agar. During incubation, the bacteria multiply, forming a visible haze of cells. If the bacterial strain is susceptible to a specific type of phage, a clear area will form at the spot where bacteriophage was added. |
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| What is an antibiogram? What is a diffusion zone or zone of inhibition? |
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| Antibiotic susceptibility patterns can distinguish different strains. A culture is uniformly inoculated onto the surface of nutrient agar. Paper discs containing different antibiotics are then placed on the agar, after incubation, clear areas will be visible around discs of antibiotics that inhibit or kill the organism. |
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| 25. What is a bacteriophage? |
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| A virus that infects bacteria, often shortened to phage. |
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| What are viruses made up of? |
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| Either DNA or RNA (never both) and protein. Optional additional layers |
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| What is a virion? |
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| A complete virus in its inert non-replicating form also referred to as a viral particle. |
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| 1. Be able to list characteristics of eukaryotes |
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| a. Eukaryotes will be a Fungus, Protist, Plant, or Protozoa; will have a defined, membrane bound nucleus; will have many organelles, will generally be bigger; will have a different size of ribosomes than prokaryotes (80s). |
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| 2. Know general characteristics of fungi |
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| a. Fungi have chitin in the cell wall instead of cellulose. They are multicellular. They are saprophytic (meaning they grow on dead material). They are decomposers. All fungi are heterotrophs (do not photosynthesize, must get nutrients from environment). Some will be associated in symbiotic relationships |
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| 3. What are hyphae? Mycelia? Mushroom? |
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| a. Hyphae are a long, branching filamentous structure of a fungus. b. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. c. A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. It is composed of the myecelium |
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| 4. How are fungi classified? |
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| a. Fungi are classified as the Fungi kingdom in the Eucarya domain. They are differentiated from other Eukaryotes by the chitin in their cell walls and by their reproductive structures: the hyphae, spores, conidia, mushrooms |
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| 5. Know 4 divisions of fungi and basis for fungal classification and examples |
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| a. Remember there are four divisions, and examples, bread mold, penicillin, b. Chytrids: live in water, only fungi with motile forces, some parasitic c. Zygomycetes: black bread mold (Rhizophus), reproductive structures called sporangia d. Ascomycetes: lichens, truffles, penicillium, pathogens e. Basidiomycetes: mushrooms, plant parasites |
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| 6. Where would you find fungi growing? |
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| a. Fungi grow in mostly terrestrial habitats (Chytrid fungi are usually found in water). It can be found in nearly every habitat on earth, including thermal pools, volcanic craters, high salt environments. Some are widespread, and some are specific to their environments. They are most successful in moist places. |
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| 7. What are conidia? |
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| a. Conidia are asexual spores of fungi. |
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| 8. What are asexual spores of fungi called? |
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| conidia |
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| 9. What is Mycosis? |
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| a. Fungal diseases that affect animals, primarily humans. |
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| 10. What is the term for fungus growing on your body and causing a disease |
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| mycoses |
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| 11. Do many fungi cause diseases in humans? |
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| a. Few do directly: athlete’s foot, candidiases. Some fungi produce toxins, that when eaten by animals do not affect them but store up the toxin, then when they are eaten by humans, the humans are affected. |
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| 12. What are lichens? |
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| a. Symbiotic relation between algae and fungi. The fungus provides the shelter and growing platform, also draws in water and minerals. The algae provides photosynthetic nutrients. |
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| 13. Importance of fungi: |
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| a. Fungi are decomposers (break down dead material), vital to antibiotic production (penicillium), and important to the food industry (yeast, truffles, mushrooms). b. Also detrimental: spoils food, crop diseases c. medical |
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| 14. What is a trophozite? |
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| a. Polymorphic protozoa can exist as vegetative or feeding form of protozoa (active form) |
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| 15. What is a cyst? |
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| a. Polymorphic protozoa can respond to environmental stimuli to form cysts, which are the resting form of the trophozite, such as lack of nutrients, moisture, oxygen, chemicals. Some cysts have cell walls to protect the cyst during host transfer, or from stomach acid. |
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| 16. Know major characteristics and examples of Apicomplexa, Flagellates, Parabasalids |
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| a. Apicomplexa: Protozoan parasites with apical complex at one end to help penetrate membrane of host cells, many complex life cycles, alternate between sexual and asexual forms (examples: plasmodium which causes malaria) b. Flagellates: Flagellates are organisms with one or more whip-like organelles called flagella (sperm, red tide) c. Parabasalids: flagellated protists lacking mitochondira, reproduce asexually, live within host (digest cellulose), some cause disease (trichomonas vagibakus) |
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| 17. Know general characteristics of algae |
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| a. Algae are simple eukaryotic protists. They are photosynthetic with no organized vascular system (how they differ from plants), can be small or large. Most are aquatic, cellulose cell walls, can be unicellular or muticellular. |
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| 18. Where do algae grow? |
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| a. Algae tend to grow in aquatic environment, free floating or in long chains or filaments. |
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| 19. What are following structures: stalk, holdfast, blades |
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| a. Blades: site of photosynthesis b. Holdfast: for anchoring the algae c. Stalk (stipe): has blades attached to it |
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| 20. How do algae reproduce? |
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| a. Sexual: alternate between haploid and diploid generation b. asexual (by fragmentation; pieces of the algae break off, then continue to gorw) |
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| 21. What is fragmentation? |
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| a. Asexual reproduction; the algae breaks into parts to form new algae |
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| 22. What is the asexual reproduction of algae called? |
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| a. Fragmentation |
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| 23. What are dinoflagellates? What do they cause? |
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| a. DInoflagellates are a large group of flagellate protists. Most are marine plankton, but are common in fresh water as well. Many are photosynthetic, but can combine this with ingesting prey. Largest group of marine eukaryotes besides diatoms. b. Can cause red tide (Gonyaulax, which produces toxins that shellfish feed on withoui harm, but can cause paralysis to humans that eat those shellfish because cookng does not destroy) |
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| 24. What do you mean by vectors? |
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| a. Vectors are disease-carrying animals that can transmit diseases to humans by mechanical (trasnsfer pathogen from one surface to another) or biological transmission (essential part of life cycle) |
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| 25. What are arthropods? |
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| a. Insects and arachnids (lice, mites, ticks, mosquitoes, fleas) |
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| 26. What is asciriasis? |
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| a. Ascariasis is the most common roundworm disease, caused by the Helminth nematode (roundworm) |
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| 27. What causes Lyme disease? |
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| a. Lyme disease is caused by the wood tick Ixodes scapularis, which transmits the bacterium Borrelia burgdorferi |
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