Question | Answer |
What defines a microorganism? | Living things that can't be seen by the naked eye. |
What are some basic examples of microorganisms? Why are they difficult/easy to study? | Bacteria, Archae, Protozoa, Fungi, Helminths and Viruses
Easy because the reproduce so rapidly and we can quickly grow large populations in the lab:Difficult because they can't be seen by the naked eye. We rely on indirect methods for analyzing them. |
What are the 3 domains? Describe briefly. Where are microbes found? | Bacteria, Archae, Eukarya. The three domains stemed fromthe last common ancestor. All biological life falls into these three categories. Microbes are found in the earth's crust, the polar ice caps, oceans, and inside the bodies of plants and animals. |
What are some uses of microorganisms?(Food, bio-remediation, useful products)Be able to give examples | bread production, cheese production, alcohol production, treatment of wounds and lesions(recombinant dna tech), cleaning up human created contamination(bio-remediation) |
What are the past, present, and future triumphs of medical microbiology? (emerging/re-emerging diseases) Vaccinations | Aids, Hepatitis C, TB, West Nile virus(re-emerging/emerging diseases) from deforestation and industrialization, antibiotic overuse making microbes resistant to drugs, herd immunity when a large population becomes immune to an infection through the use of |
What is spontaneous generation? Who disproved it? Who tried to prove it true? What did they do in their experiments? How were the experiments set up? | Spontaneous generation is the theory that living things rose from nonliving things. leeuwenhoek,redi,spallanzani, and pasteur tried to disprove it and needhamtried to prove it. |
What is the germ theory of disease? | theory that microorganisms can cause disease |
The microbial world/cellular organiizations= 3 domains | Eukaryotic cells contains organelles encased by membranes that perform specific functions. Bacteria and Archae are prokaryotic and don't have organelles, have complex structures and can engage in every activity that eukaryotic cells can |
What are some characteristics of bacteria? | all bacteria have cell membrane, cytoplasm, cytoskeleton, ribosome, one of few chromosomes |
Archae- Conditions for survival? (Salt, high temp, low pH) | low temperature archae are psychrophilic, high temperature loving are hyperthermophilic, extremophiles can live in high salt concentrations |
Eukarya- What groups are found here/ | animals, fungi, plants |
What are viruses and how do they affect us? | non living, non cellular having microbes that can infect any living cell and cause disease. |
Nomenclature-binomial method. How does it work? | the assignment of scientific names to the various taxonimic categories and individual organisms. The scientific name is always a combination of the genus name followed by the species name. genus is capitalized, species is lowercase. both underlined |
What is the Woese- Fox system of taxonomy? what is it based upon? | system that assigned all organisms into the 3 domains. based on conserved small subunit ribosomal RNA sequences (ssu rRNA) |
What is Spontaneous Generation? | Spontaneous generation was a theory that living things came from nonliving things. |
Know the history of who did what(Hooke) | Invented the microscope making it easier to study microorganisms because they were too small for the naked eye to see. |
Know the history of who did what(Redi) | disproved spontaneous generation by putting fresh meat in 2 separate jars, one sealed off with cheese cloth and the other was left open. The open jar filled with maggots on the meat proving that maggots came from fly eggs. |
Know the history of who did what(Needham) | tried to prove spontaneous generation by putting gravy in 2 separate flasks, melted the top of one and left the other open. he heated both flasks but not enough to kill the microbes thus creating false results that life rose from nonliving things |
Know the history of who did what(Spallanzani) | disproved spontaneous generation by boiling two separate bottles of broth, sealing one and leaving the other open. The sealed bottle had no sign of life while the other had microbes floating inside. |
Know the history of who did what(Pasteur) | disproved spontaneous generation by putting broth in 2 separate flasks with long swan neck openings. The openings were free to air but curved so that dust particles could become trapped. He then heated the flasks and incubated them. The necks stopped micr |
Know the history of who did what(Koch) | four criteria to help identify the causative agent of a disease. |
Know the history of who did what(Leeuwenhoek) | contributed to microbiology by discovering protozoa and improving the microscope through lens grinding |
What dimensions do we use when looking at microorganisms? | 4x(scanning resolution), 10x(low power), 40x(high power), 100x (oil immersion) |
How do we get good resolution when looking at a specimen in the microscope? | by adjusting the magnification and regulating the light |
Who is christian gram and what is his contribution to microbiology? | Danish bacteriologist who contributed to microbiology through the development of the gram stain for bacteria classification and identification. |
What is a stain? | A reagent or dye that is used for staining( any procedure that applies colored dyes to a specimen) |
what are the 2 types of dyes that we use? | basic(cationic) which have a positive charge or acidic(anionic) which have a negative charge. cells with negative charge attract basic dyes. Acidics are good for staining the backgrounds. basic dye stains cell |
Simple vs differential | Simple uses one due while differential uses 2. Differential are more complex. Simple stains all appear the same color |
Why is differential so important to the field of microbiology? | Because it is used to help identify bacterial species and guide treatment. |
How do we perform a gram stain? What is the purpose of each step? | 1.Crystal violet is added to cells staining them all the same color. 2.mordant grams iodine is added which is a stabilizer 3.alcohol is added dissolving away the outer membrane of the gram -4applying safranin demonstrates the presence of gram- |
Different microscopes (darkfield) | Visualize living cells. The background is dark but the specimen is bright |
Fluorescent | UV source. Diagnosing infections and pinpointing cellular structures |
Brightfield/compound | For every day use to look at cells. Light is transmitted thru the specimen, live unstained materiail, preserved stained material |
Scanning electron | Electromagnetic source detailed 3 dimensional view of all kinds of objects |
Transmission electron | For cells and viruses. Specimen have to be sectioned into extremely thin slices |
Acid fast stain | Distinguish acid fast (pink) bacteria from non acid fast (blue) detect mycobacterium TB using the carbol fuchsin dye |
Endospore | Distinguish between endospores and the cells that they came from (vegetative) detecting anthrax, botulism, and tetanus. Malachite green dye |
Capsular | Known as a special stain, used to observe the microbial capsule . Repels most stains, often negatively stained with India ink or special positive stains. Cryptococcus -fungal meningitis in aids patients |
How are bacteria and archae different from eukaryotes | The way their DNA is packaged, their internal structure, their cell wall |
What do all bacteria cells have? | Cell membrane, cytoplasm, cytoskeleton, ribosome, one of few chromosomes |
Morphology (cocci) | Spherical or round shape |
Morphology(bacilli) | Rod shape, cylyndrical, spindle shape, blocky, round ended |
Morphology(spiral) | Slightly curled spiral shape |
Cell arrangements(diplococcus) | Two cells |
Cell arrangements (stretocococcus) | Variable # of cocci in chain |
Cell arrangements(tetrads) | Packets of 4 |
Cell arrangements(sarcina) | Packets of 8-64 |
Cell arrangements(staphylococcus) | Cluster (grapes) |
External structure (flagellum) | Motility |
Pillus | Long rigid tubular structure made of special protein. Motility, transfer of DNA , attachment |
Fimbriae | Attachment-small bristlelike, lead to biofilms |
Nanotubes | Thin long tubular extensions of the cytoplasmic membrane used to transfer amino acids or electrons |
Glycocalyx capsule or slime layer | (composed of sugar)Slime layer is loose shield. Capsule fits more tight denser and thicker |
What is the cell envelope? | External covering that lies outside the cytoplasm composed of 2-3 layers: cell wall, cytoplasmic membrane, outer membrane(gram-) |
Gram+ cell wall | Thick sheath of peptidoglycan, contains acidic polysaccharides including teichoic acid and lipoteichoic acid which functions I'm cell maintenance, enlargement and acidic charge. |
Gram- cell wall | Thin sheath of peptidoglycan containing lipoprotein, lipopolysacchirides, phospholipids , porin proteins |
Targeting peptidoglycan | Penicillin and cephalosporins are effective bc they target peptide crosslinks in the peptidoglycan causing it to disintegrate |
Mycobacterium | Does not contain cell wall thus making it resistant to drugs and dyes so the use of an acid fast dye bc it is composed of mycolic acid |
Internal structures (chromosomes) | Bacteria DNA found here |
Plasmid (nonessential DNA) | Protective traits such as resisting drusgs |
Ribosome | Sites of protein synthesis |
Inclusions | Storage for environmental conditions like food |
Cytoskeleton | Cell shape and stability |
Endospores | Dormant bodies produced by bacteria when environmental conditions become challenging |
What are the members of the eukaryotic world | Protozoa, fungi, heminths |
What is a glycocalyx and why is it important | An outermost layer that comes in contact with the environment. Contributes to protection, adherence and reception of signals from other cells |
Which eukaryotes have a cell wall and which do not | Protozoa and helminths do not have cell walls but fungi do |
What is a cell wall made of? | The inner layer of polysaccharides is composed of chitin or cellulose, the outer layer is mixed glycans |
How does it differ from bacteria? | They are different I'm chemical composition. Rigid, provide structural support and shape. |
How does cell wall vary in eukaryotes? | They have 2 layers, an inner layer of polysaccharides that can be composed of cellulose or chitin and an outer layer of mixed glycans |
What is the nucleus? Why important? | It is a compact sphere and the most prominent organelle. It contains the genetic material, the DNA, which is responsible controlling and directing all activities of the cell. |
What groups are found within the fungi and what forms do they take | Yeasts, molds, puffballs, and mushrooms with the cell types of hyphae and yeasts |
What are some important characteristics of fungi | Isomorphic- can take either form of a mold to yeast in response to growth conditions such as temperature. |
What is a fungus made of? | Hyphae that that make up a tangled web of mycelium |
Where are fungi found? | In any habitat from sea water to fresh water, in soil, in plants and animals and human skin |
What are hyphae | Long threadlike cells found in the bodies of fungi of the filamentous type |
What are mycelia | Mass or group of hyphae that make up the body or colony of mold |
Reproduction -production of spore | Spores are dispersed widely throughout the environment by air, water and living things. Asexual spores are the products of mitotic division and sexual spores are product of meiosis the fusing of 2 parental nuclei. |
Reproduction -propagating | Simple outward growth of an existing hyphae |
Reproduction -fragmentation | Separate piece of mycelium can generate a whole new colony |
How do fungi affect us economically (negative) | Damages field plants such as corn and grain. Reduce crop production and cause disease in domestic animals |
How do fungi affect us economically (positive) | The aid in production of antibiotics, alcohol, organic acids and vitamins. Decomposing organic matter and and returning essential minerals to the soil |
How do fungi affect humans | They cause mycoses in humans through hospital acquired, opportunisticly from immunocompromised individual, and via the environment |
What is a lichen? What are mycorrhizae? | Lichens are the first sign of life after a natural disaster occurs. Mycorrhizae are structures that help increase the ability of roots to absorb water and nutrients |
What defines protozoa | Single celled microscopic animal, reproduce by asexual methods of mitotic cell division |
How do we characterize them? | Cytoplasm is divided into 2 layers. Ectoplasm responsible for locomotion,feeding, and protection. Cytoplasm responsible for housing the nucleus, mitochondria, food and contractile vacuoles. |
What are some characteristics | Unicellular, no cell wall, freeliving inhabitants of water and soil |
What are helminths? How do they affect us? | Tapeworms and flukes are flatworms. Nematodes are round worms. They affect humans through infection by ingestion of through penetration of tissue by the worm. Contaminated good soil or water or other infected animals |
How do they reproduce? | A complete cycle includes the fertilized egg, larval, and adult cycle. Reproduce sexually. I'm trematodes the sexes are hermaphoditic. Nematodes the sexes are separate. |
What is the goal? | Completing the entire life cycle. |
Intermediate host? | Host in which the larval develops |
Definitive host? | Host in which adult mating occurs |