Principles of Microbiology- study guide for exam 1
Principles of Microbiology- study guide for exam 1 BIO 2440
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This 19 page Study Guide was uploaded by Amanda Notetaker on Saturday October 1, 2016. The Study Guide belongs to BIO 2440 at Texas State University taught by greg able in Fall 2016. Since its upload, it has received 8 views. For similar materials see principles of microbiology in Microbiology at Texas State University.
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Exam 1 – Study Guide Microbiology 2440 Fall 2016 Learning Objectives Check Your Understanding 1.1 List several ways in which microbes affect our Describe some of the destructive and beneficial lives. actions of microbes. Prevent food spoilage Destructive: Prevent disease Pathogenic microbes (disease producing) Helps us understand causes and Beneficial: transmission of disease to prevent Balance in environment epidemics Fresh water/ soil microbes important role in photosynthesis Food industry (vinegar, alcohol drinks, & cheese Clothes 1.2 Recognize the system of scientific Distinguish a genus from a specific epithet. nomenclature that uses two names: a genus and a Escherichia coli specific epithet. ↑ ↑ Genus First name (caps) Genus Specific epithet Specific epithet species name that follows (not in caps) Always underlined or italicized 1.3 Differentiate the major characteristics Which groups of microbes are prokaryotes? Which of each group of microorganisms. are eukaryotes? Bacteria Prokaryotic Bacteria and Archaea Eukaryotic Fungi, Protozoa, Algae, and Prokaryotic Unicellular Multicellular Animal Parasites (humans relate to fungi and protozoa) Peptidoglycan cell walls Divide via binary fission Protozoa Nutrients from organic and inorganic chemicals or photosynthesis Eukaryotic Archaea absorb and ingest organic chemicals Motile via pseudopods, cilia, or Prokaryotic flagella Lack peptidoglycan cell walls Free living or parasitic(nutrients from Live in extreme environments host) NOT known to cause disease in humans Unicellular Methanogens: methane= waste Algae Halophiles: salt loving Eukaryotic Thermophiles: heat loving Cellulose cell walls Fungi Found in freshwater, saltwater, and soil Eukaryotic Photosynthesis for energy Chitin cell walls (sugar chains) Produce oxygen and carbohydrates Absorb organic chemicals for energy Yeast= unicellular Viruses Mold/Mushrooms= multicellular Acellular Molds consist of mycelia, which are Has DNA or RNA (not both) composed of filaments called hyphae core is surrounded by protein coat (found on fruit and bread) core may be enclosed by lipid envelope Multicellular Animal Parasites replicated when living in host cell Eukaryotic Inert outside living hosts Not microorganism Medical importance parasitic flatworms and roundworms = helminths 1.4 List the three domains. What are the three domains? Bacteria (origin of mitochondria) Created by Carl Woese Archaea (origin of Chloroplasts pre living They divide all life bacteria) 6 Kingdoms = Bacteria, Fungi, Archaea, Eukarya Protists, Animals, & Plants 1.5 Explain the importance of What is the cell theory? observations made by Hooke and All living things are composed of cells van Leeuwenhoek. Hooke living things are composed of little boxes or “cells,” marked the beginning of cell theory. Van Leeuwenhoek observed first microbes. “Animalcules” viewed through magnifying lens. Drew organisms from rainwater, feces, scrapes off teeth, and sperm 1.6 Compare spontaneous generation and biogenesis. What evidence supported spontaneous Spontaneous Generation: Some forms of life generation? could arise spontaneously from nonliving matter. Maggots from decaying corpse “Vital force” is necessary for life. Flies emerge from manure Biogenesis: Living cells arise from preexisting cells 1.7 Identify the contributions to How was spontaneous generation disproved? microbiology made by Needham, By Pasteur, he used S shaped flask to microbes out, Spallanzani, Virchow, and Pasteur. but let in air. Broth showed no signs of life, the neck Needham: Microbes develop spontaneously from of flask trapped the microbes. Proved microbes are fluids present in air, but air doesn’t create microbes. Can be Spallanzani: Microbes from air entered fluids destroyed by heat. Virchow: Theory of Biogenesis, but had no proof no mystical force Pasteur: Proved Biogenesis 1.8 Explain how Pasteur’s work Summarize in your own words the germ theory of influenced Lister and Koch. disease. Lister applied Pasteur’s work to show that By Koch, microorganism might cause disease. microbes in air can spoil food and cause animal Realization that yeast play a crucial role in diseases. He used antiseptic (phenol) to prevent surgical wound infections. fermentation was the first link of activity of microorganism of physical and chemical changes in Koch established experimental steps for directly organic material. linking a specific microbe to a specific disease. 1.9 Identify the importance of Koch’s What is the importance of Koch’s postulates? postulates. He proved proof that certain diseases came from Demonstrate that a specific microbe causes a certain microbes, which in the long run will help us specific disease. (germ theory) see where a certain disease came from and how to prevent it with medicine. 1.10 Identify the importance of Jenner’s work. What is the significance of Jenner’s discovery? Discovered immunity. He inoculated a person with He created the first Vaccination (give body heads up) cowpox virus who was then immune to smallpox. Vacca = cow Protection= immunity 1.11 Identify the contributions to What was Ehrlich’s “magic bullet”? microbiology made by Ehrlich and Fleming. Hunt down and destroy pathogen without harming the Ehrlich: Magic bullet infected host Fleming: First antibiotic Penicillin by accident chemotherapy synthetic drugs (chemotherapeutic agents prepared from chemicals in lab) // antibiotics 1.12 Define bacteriology, mycology, Define bacteriologyHeide schulz, mycology 10% of parasitology, immunology, and hospital infections, parasitologyAsclepius, God of virology. Medicine, immunologyRebecca Lancefield, and Bacteriology: study of bacteria virologyIwanowski (electron microscope). Mycology: study of fungi Parasitology: study of parasitic worms and protozoa Immunology: Study of immunity Virology: study of viruses 1.13 Explain the importance of microbial genetics and Differentiate microbial genetics from molecular biology. molecular biology. Microbial genetics: Study of microbes inherit Microbial genetics is hoe microbes inherit traits and traits molecular biology looks at how info is carried in the molecules of DNA and how it directs protein Molecular Biology: Study of how DNA directs protein synthesis synthesis 1.14 List at least four beneficial activities Name two beneficial uses of bacteria. of microorganisms. Recycling of environment and synthesis for some Fermentation, balance in environment, role in vitamins (Bmetabolism and Kblood clotting) photosynthesis, intestine digestion 1.15 Name two examples of biotechnology that use Differentiate biotechnology from recombinant DNA recombinant DNA technology and two examples technology. that do not. Biotechnology is more practical applications related Biotechnology used for commercial use of and Recombinant DNA technology is taking microorganisms to produce some common foods something and inserting it into something else to and chemicals. create a protein or replace something such as gene clean up pollutants= bioremediation therapy. Recombinant DNA technology is inserting recombinant DNA into bacteria to make large quantities of a desired protein. Paul Berg: animal DNA into bacteria to create animal protein gene therapy enables bacteria and fungi to produce a variety of proteins, vaccines, and enzymes 1.16 Define normal microbiota and Differentiate normal microbiota and infectious resistance. disease. Normal Microbiota: “flora” microbes normally Normal microbiota prevent growth of pathogens, present in and on human body. Not harmful and produce growth factors such as vitamins B and K. protect us. Resistance ward of disease, factors include skin, Resistance: the ability of body to ward off disease stomach acid, and antimicrobial chemicals 1.17 Define biofilm. Why are biofilms important? Complex aggregation of microbes Protect your mucous membranes from harmful microbes, and in lakes are important for food in aquatic animals 1.18 Define emerging infectious disease. What factors contribute to the emergence of an infectious disease? New diseases and diseases increasing in incidence Evolutionary changes in living organisms spread of diseases by transportation to new country new human exposure to unusual infectious agents in areas undergoing ecological change (deforest and construction) Learning Objectives Check Your Understanding 31 List the metric units of measurement that If a microbe measures 10 μm in length, how long is it in are used for microorganisms. nanometers? Micrometers and nanometers 10,000 nm 32 Diagram the path of light through a Through what lenses does light pass in a compound compound microscope. microscope? Bottom to top Condenser 33 Define total magnification and resolution. What does it mean when a microscope has a resolution Total Magnification: objective lens x ocular lens of 0.2 nm? Resolution: ability of lenses to distinguish two points It can distinguish between two points at least 0.2 nm (fine detail and structure) Increases with apart decreasing wavelength 34 Identify a use for darkfield, phasecontrast, How are brightfield, darkfield, phasecontrast, and fluorescence differential interference contrast, fluorescence, confocal, twophoton, and scanning microscopy similar? acoustic microscopy, and compare each with They all have a solid color back ground and you can see brightfield illumination. distinctly the microscopic organism Each show distinct features of the microorganism, see each on solid background like brightfield. 35 Explain how electron microscopy differs from Why do electron microscopes have greater resolution light microscopy. than light microscopes? Electron microscopy uses electrons instead of light Because the shorter wavelength of electrons gives greater resolution. 36 Identify one use for the TEM, SEM, and scanned For what is TEM used? SEM? probe microscopes. Scannedprobe microscopy? TEM: Examine viruses or internal ultrastructure in thin TEM and SEM use beam of electrons sections of cells ( usually magnified 10,000 Scannedprobe use a thin metal probe that scans 10,000,000x) specimen and produces image that reveals bumps and SEM: Study surface features of cells and viruses depressions of the atoms on surface. (usually magnified 1000500,000x) Scannedprobe: Provides very detailed views of molecules inside cells. 37 Differentiate an acidic dye from a basic dye. Why doesn’t a negative stain color a cell? Acidic: chromophore = anion Because acidic dyes are not attracted to most types of bacteria because the dyes negative ions are repelled by Basic: chromophore= cation negatively charged bacterial surface (stains background instead) 38 Explain the purpose of simple staining. Why is fixing necessary for most staining procedures? Used to highlight the entire microorganism so that A mordant is used to hold the stain or coat the specimen cellular shapes and basic structures are visible to enlarge it 39 List the steps in preparing a Gram stain, and Why is the Gram stain so useful? describe the appearance of grampositive and Provides valuable information for the treatment of gramnegative cells after each step. disease Gram Stain Gpositive= tend to be killed easily by penicillin and 1. Heat fix smear application of crystal violet cephalosporin (purple dye) primary stain G negative= more resistant because antibiotics cannot 2. Application of iodine (mordant) penetrate the lipopolysaccharide layer 3. Alcohol wash (decolorization) 4. Application of safranin (counterstain) Gram Negative: appearance= loose purple color after decolorization.. until counterstained with red dye Gram Positive: appearance= retain color after alcohol has attempted to decolorize 310 Compare and contrast the Gram stain and the acid Which stain would be used to identify fast stain. microbes in the genera Mycobacterium and Nocardia? In comparison they both have decolorization, use Acid Fast Stain of red dye, and alcohol wash, but in contrast the acid fast stain after decolorization only shows bacteria that are acid fast or not and in gram negative it has to be stained with red dye after to avoid being colorless. 311 Explain why each of the following is used: How do unstained endospores appear? Stained capsule stain, endospore stain, flagella stain. endospores? Capsule stain: Used to demonstrate the presence of Normal under unstained because they are highly capsules. Because capsules don’t accept most refractive. stains, the capsules appear as unstained halos Stained = Green around bacterial cells and stand out in contrasting background Endospore stain: Used to detect the presence of endospores, malachite green stain on endospores Flagella stain: Used to demonstrate presence of flagella a mordant is used to enlarge flagella until visible Learning Objectives Check Your Understanding 41 Compare and contrast the overall cell structure What is the main feature that distinguishes of prokaryotes and eukaryotes. prokaryotes from eukaryotes? Prokaryote One circular chromosome not in a membrane They both have nucleic acids, proteins, lipids, and carbohydrates, but differ in that they have different No histones structure of cell walls and absence of organelles. No organelles Bacteria: Peptidoglycan cell walls Archaea: Psuedomurein cell walls Divide by binary fission Eukaryotes Paired/multiple chromosomes in nuclear membrane Membrane bound organelles Histones and nonhistones Polysaccharide cell walls, when present Divide by Mitosis (growth, repair, & replace) 42 Identify the three basic shapes of How would you be able to identify bacteria. streptococci through a microscope? Range from 0.2 to 2.0 micrometers Looks like a chain of circles going in one direction Coccus circular single lateral plane Bacillus rod shape Spiral vibrio, spirillum, and spirochete Star shaped Rectangular Monomorphic one shape ( most bacteria) Pleomorphic several shapes 43 Describe the structure and function of Why are bacterial capsules medically the glycocalyx. (sugar coat) important? Substance that surround cells Because the capsules hide the bacteria and it can go unnoticed in our immune system because our blood cells Vicous ( sticky) & gelatinous polymer recognize by feeling and the capsule disguises it Made of polysaccharide & or /polypeptide or both Made inside cell and secreted to cell surface Two types are capsules: neatly organized and firmly attached to wall; Slime Layer: Unorganized and loose to wall Contributes to virulence (degree to which a pathogen can cause disease) Capsules protect phagocytosis Extracellular polymeric substance helps form biofilms (allows cells to survive) 44 Differentiate flagella, axial filaments, fimbriae, How do bacteria move? and pili. Flagella Flagella: long filamentous appendages that propel bacteria (run/tumble in one direction) Fimbriae: hair like appendages that allow for attachment Pili: Involved in motility (gliding and twitching) and Conjugation pili = DNA transfer 45 Compare and contrast the cell walls of gram Why are drugs that target cell wall synthesis useful? positive bacteria, gramnegative bacteria, acid fast bacteria, archaea, and mycoplasmas. Because they do not harm the host Gram Positive bacteria: Thick peptidoglycan & teichoic acid (alcohol and phosphate), 2 rings in basal body of flagella, produce exotoxins, high susceptibility to penicillin, and disrupted by lysozyme Gram negative bacteria: Thin peptidoglycan, outer membrane, & periplasmic space (region between outer membrane and plasma membrane), 4 ring, endotoxins (LPS)/exotoxins, low susceptibility to penicillin Acidfast bacteria: Like gram positive, waxy lipid (mycolic acid) bound to peptidoglycan (no gram reaction), Mycobacterium/ Nocardia stain with carbolfouchsin (red) Archaea: Atypical, wall less or walls of peudomurein (lack NAM and D amino acids/ repeating carbohydrate chains) – mimic Euk. cells Mycoplasmas: Atypical, lack cell walls, & sterols in plasma membrane 46 Compare and contrast archaea and Why are mycoplasmas resistant to antibiotics that mycoplasmas. interfere with cell wall synthesis? Both lack cell walls Because their plasma membranes contain lipids called sterols which are thought to help protect them from lysis Differ by substances in each and archaea can have unusual walls composed of polysaccharide and (rupture) proteins, but not peptidoglycan 47 Differentiate protoplast, spheroplast, How do protoplasts differ from L forms? and L form. Different shape and different capabilities Protoplast wall less gram positive cell, spherical Protoplast carrying on metabolism Spheroplast wall less gram negative cell L form live and divide repeatedly or return to Both are susceptible to osmotic lysis the walled state L form wall less cells that swell into irregular shapes 48 Describe the structure, chemistry, and functions Which agents can cause injury to the bacterial of the prokaryotic plasma membrane. plasma membrane? Structure= fluid mosaic model Alcohols, quaternary ammonium (detergents), and Function= selective permeability polymyxin antibiotics causes leakage of cell contents Chemistry= breakdown of nutrients and production of ATP 49 Define simple diffusion, facilitated How are simple diffusion and facilitated diffusion, osmosis, active transport, diffusion similar? How are they different? and group translocation. Both passive, facilitated requires help from protein to Simple: passive, movement of solute from high to low transport ions and larger molecules Facilitated: passive, combines w/ a transporter protein Osmosis: passive, movement of water high to low Active: requires energy, low to high 410 Identify the functions of the nucleoid Where is the DNA located in a prokaryotic cell? and ribosomes. Nucleoid Nucleoid: contains bacterial chromosomes ( genetic info) and plasmids ( extrachromosomal genetic elements; carry non crucial genes antibiotic resistance and production of toxins) Ribosomes: protein synthesis, made of protein and rRNA 411 Identify the functions of four inclusions. What is the general function of inclusions? Metachromiatic granules (volutin) –phosphate Reserve deposits reserves Polysaccharide granules energy reserve Lipid inclusions energy reserve Sulfur granules energy reserve 412 Describe the functions of endospores, Under what conditions do endospores form? sporulation, and endospore germination. Extreme conditions such as high heat Endospores: resting cells, resistant to desiccation, heat, chemicals, and radiation Sporulation: endospore formation (within vegetative cell) Endospore germination: endospore returns to vegetative state (triggered by high heat) 413 Differentiate prokaryotic and eukaryotic flagella. Prokaryotic: consist of 2 protein building blocks Eukaryotic: complex, consist of multiple microtubules 414 Compare and contrast prokaryotic and eukaryotic cell walls and glycocalyxes. Prokaryotic: Usually present, chemically complex (peptidoglycan) Identify at least one significant difference between eukaryotic and prokaryotic flagella and Eukaryotic: When present, chemically simple (cellulose & chitin) cilia, cell walls, plasma membranes, and cytoplasm. Movement in Prokaryotic is rotation, Eukaryotic is wave Glycocalyxes: In Eukaryotic cells such as animal cells, covers plasma membrane carbohydrates bounded like; cilia are numerous short projections; cell walls are to proteins and lipids in plasma membrane outer walls surrounding cell made of carbohydrates (found in plants, algae, and fungi); plasma membranes 415 Compare and contrast prokaryotic and eukaryotic plasma membranes. separates outside from inside; cytoplasm is substance inside the plasma and outside the nucleus. Prokaryotic: carbohydrates and generally lack sterols Eukaryotic: sterols and carbohydrates that serve as receptors (endocytosis) 416 Compare and contrast prokaryotic and eukaryotic cytoplasm. Prokaryotic: Cytoskeleton, no cytoplasmic streaming Eukaryotic: Cytoskeleton, cytoplasmic streaming 417 Compare the structure and function of The antibiotic erythromycin binds with the 50S eukaryotic and prokaryotic ribosomes. portion of a ribosome. What effect Both used for protein synthesis does this have on a prokaryotic cell? On a eukaryotic cell? It will effect prokaryotes more because they are Prokaryotic: smaller size 70s smaller Eukaryotic: Larger size 80s; smaller size in organelles 70s 418 Define organelle. Compare the structure of the nucleus of a Structures with a specific shape/ function and are eukaryote and the nucleoid of a prokaryote. characteristics of eukaryotic cells Prokaryote: Pre nucleus/ no nucleus, bunch of bacterial chromosomes Eukaryote: true nucleus, nuclear membrane and nucleoi 419 Describe the functions of the nucleus, How do rough and smooth ER compare endoplasmic reticulum, Golgi complex, structurally and functionally? lysosomes, vacuoles, mitochondria, chloroplasts, Both synthesize phospholipids, both are flattened sacs peroxisomes, and and extensive networks centrosomes. Nucleus: DNA ER: Rough= site of protein synthesis, smooth= no ribosomes, synthesizes cell membrane, fats, and hormones detoxify drugs (alcohol, lots of liver cells) Golgi: Package and transport Lysosomes: digestive enzymes Vacuoles: provide shape and storage, bring food into cells ( storage= proteins, sugars, inorganic ion/organic acids) 420 Discuss evidence that supports the Which three organelles are not associated with the endosymbiotic theory of eukaryotic Golgi complex? What does this evolution. suggest about their origin? It is Larger bacterial cells engulfed smaller bacterial celMitochondria and Chloroplast, origin in prokaryotes. developing the first eukaryotes Lynn Margulis Studies comparing pro/eukaryotic cells Both mitochondria and chloroplasts resemble bacteria in size and shape These organelles Contain circular DNA and reproduce independently like prokaryotes Their ribosomes resemble prokaryotes and mechanism found of protein synthesis Same antibiotics inhibit protein synthesis on ribosomes in bacteria and these organelles Learning Objectives Check Your Understanding 61 Classify microbes into five groups on the basis of Why are hyperthermophiles that grow at preferred temperature range. temperatures above 100°C seemingly limited to Psychrophiles oceanic depths? Because it’s way too cold in the ocean, they love extreme heat Psychrotrophs Mesophiles Thermophiles Hyperthermophiles 62 Identify how and why the pH of culture media is Other than controlling acidity, what is an controlled. advantage of using phosphate salts as buffers in growth media? Chemical buffers (peptones, amino acids, and phosphate salts) They have the advantage of exhibiting their buffering effect in pH growth range of most bacteria, also non toxic, provide phosphorus as essential nutrient 63 Explain the importance of osmotic Why might primitive civilizations have used food pressure to microbial growth. preservation techniques that rely on It effects the removal or addition of water to the cell, it osmotic pressure? could, shrink or burst. Water is very important to Increased osmotic pressure/ addition of salts or other the cell’s nutrients. solutes help preserve foods. The OP effects are related to the number of dissolved molecules and ions in volume of the solution. 64 Name a use for each of the four If bacterial cells were given a sulfur source elements (carbon, nitrogen, sulfur, and containing radioactive sulfur ( S) in their 35 phosphorus) needed in large amounts culture media, in what molecules would the S be for microbial growth. found in the cells? Carbon: structural backbone of living matter, needed to Proteins make up living cell Nitrogen: component of proteins, DNA, RNA, and ATP Sulfur: Used in amino acids, thiamine, and biotin Phosphorus: Used in DNA, RNA, and ATP (essential for nucleic acids, and phospholipids) 65 Explain how microbes are classified on the basis How would one determine whether a microbe is a of oxygen requirements? strict anaerobe? Growth either requires it, tolerates it, or is fine without Grows via fermentation, without oxygen 66 Identify ways in which aerobes avoid damage by Oxygen is so pervasive in the environment that it toxic forms of oxygen. would be very difficult for a microbe to Important to body’s defense against pathogens always avoid physical contact with it. What, therefore, is the most obvious way for a Singlet oxygen microbe to avoid damage? Superoxide radicals Avoid oxygen Peroxide anion Hydroxyl radical 67 Describe the formation of biofilms and their Identify a way in which pathogens find it potential for causing infection. advantageous to form biofilms. Bacteria communicate to each other in creating a biofilm Shelters them from harmful environmental cell to cell communication (quorum sensing) hazards facilitating transfer of genetic info by conjugation Share nutrients 68 Distinguish chemically defined and complex Could humans exist on chemically defined media, at media. least under laboratory conditions? Defined: exact chemical composition is known Possibly due to organic factors needed Complex: exact chemical composition is unknown 69 Justify the use of each of the following: Could Louis Pasteur, in the 1800s, have grown anaerobic techniques, living host cells, candle rabies viruses in cell culture instead of in jars, selective and differential media, and living animals? enrichment medium. Anaerobic techniques: Reducing media used deplete oxygen Living Host cells/candle jars: Special Culture technique Selective/ Differential media: inhibit unwanted organisms; selective= growth of only desired microbe, Differential= distinguishes different organisms Enrichment: encourage growth in mixed culture 610 Differentiate biosafety levels 1, 2, 3, What BSL is your laboratory? and 4. 1 and 2 1. No special precautionsteaching labs 2. Lab coat, gloves, eye protections 3. Biosafety cabinets to prevent airborne transmission 4. Sealed, negative pressure, “hot zone” 611 Define colony. Can you think of any reason why a colony does not grow to an infinite size, or at least fill the confines of Population of cells arising from a single cell or spore or from a group of attached cells the Petri plate? 612 Describe how pure cultures can be Could a pure culture of bacteria be obtained by the isolated by using the streak plate streak plate method if there were only one desired method. microbe in a bacterial suspension of By streaking them in to separate areas of the plate ( 1, 2, billions? 3) 613 Explain how microorganisms are If the Space Station in Earth orbit suddenly preserved by deepfreezing and ruptured, the humans on board would die lyophilization (freezedrying). instantly from cold and the vacuum of space. Would Water is removed and very low temperatures are used all the bacteria in the capsule also be killed? no 614 Define bacterial growth, including Can a complex organism, such as a beetle, binary fission. divide by binary fission? Bacterial Growth: Grow by binary fission No, they are not bacteria they’re sexual Binary Fission: Cell division into 2 daughter cells asexual 615 Compare the phases of microbial growth, and describe their relation to generation time. 1. Lag phase intense activity preparing for growth, but no increase in population 2. Log phase increase in population 3. Stationary Phase equilibrium, microbial death balances production of new cells 4. Death Phase: population is decreasing at logarithmic rate 616 Explain four direct methods of measuring cell growth. Plate counts Filtration Most probable number method (MPN) Direct Microscopic count 617 Differentiate direct and indirect methods of measuring cell growth. Direct is statistical, indirect is estimation 618 Explain three indirect methods of measuring cell growth. Turbidity Metabolic activity Dry weight Learning Objectives Check Your Understanding 71 Define the following key terms related to microbial control: sterilization, disinfection, antisepsis, degerming, sanitization, biocide, germicide, bacteriostasis, and asepsis. Sterilization: Removing & destroying all microbial life Disinfection: destroying harmful microorganisms Antisepsis: destroying harmful microorganisms from living tissue Degerming: the mechanical removal of microbes from a limited area (skin) Sanitization: lowering microbial counts on eating utensils to safe levels Biocide/Germicide: treatments that kill microbes Bacteriostasis: inhibiting, not killing microbes Asepsis: absence of significant contamination 72 Describe the patterns of microbial death How is it possible that a solution containing a million caused by treatments with microbial bacteria would take longer to control agents. sterilize than one containing a halfmillion bacteria? Effectiveness of treatment depends on: They could be more resistant Number of microbes Environment Time of exposure Microbial characteristics More time that goes by the less death occurs because a lot died minutes before leaving few survivors Ex: 1 min, 900,000 deaths, 100,000 survivors 6 min, 9 deaths, 1 survivor 73 Describe the effects of microbial control agents Would a chemical microbial control agent that affected on cellular structures. plasma membranes affect Alteration of membrane permeability ( damage to humans? yes lipids/proteins causes contents to leak into surrounding medium & interferes with growth Damage to proteins (denaturation) Damage to nucleic acids (no longer replicate/ or carry metabolic activity) 74 Compare the effectiveness of moist heat How is microbial growth in canned foods prevented? (boiling, autoclaving, pasteurization) and dry Heat heat. Thermal Death Point: the lowest temperature at which They eliminate pathogenic microbes and kill most all the microorganism in a particular liquid suspension organisms protein denaturing will be killed in 10 minutes EX: Thermal Death Time: minimal length to be killed at a moist heat = boiling given temperature autoclave= high temperatures achieved by steam under Decimal Reduction Time: time in minutes in which 90% pressure of population of bacteria will be killed at a given pasteurization= refrigeration temperature dry heat= flaming and hot air sterilization (oven) 75 Describe how filtration, low temperatures, high Why would a can of pork take longer to pressure, desiccation, and osmotic pressure sterilize at a given temperature than a can of soup that suppress microbial growth. also contained pieces of pork? They all inactivate growth of microbes in various ways.. Because cans are sterilized through high temperatures killing most microbes and pork at a given temperature Filtration: sterilize heat sensitive materials Low temperatures: reduce rate of microbes (fridge) could take longer depending on the temp. High temperatures: kill most organisms Desiccation: absence of water, microbes cannot grow or reproduce, but can be viable for years Osmotic Pressure: high concentrations of salt and sugars to preserve food (desiccation) creating hypertonic environment 76 Explain how radiation kills cells. What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen? Ionizing: creates reactive hydroxyl radicals & damages DNA by causing mutations (gamma, Ionizing radiation effect ionizes water, which forms high xrays, & high energy electron beams) reactive hydroxyl radicals which kill organisms by Nonionizing: damages DNA by creating reacting with organic cellular components thymine dimers that inhibit correct replication (UV) Microwave: kill by heat 77 List the factors related to effective If you wanted to disinfect a surface disinfection. contaminated by vomit and a surface contaminated by a sneeze, why would your choice of Organic matter pH disinfectant make a difference? So you know what will actually be effective Time Concentration of disinfectant 78 Interpret the results of usedilution tests and Which is more likely to be used in a medical clinic the diskdiffusion method. laboratory, a usedilution test or a Use dilution: testing the effectiveness of antimicrobial diskdiffusion test? agents against endospores, viruses, fungi, and Disk Diffusion mycobacteria that cause tuberculosis/ also special purposes ( dairy utensil disinfection) Disk diffusion: Used in teaching labs to evaluate the efficacy of a chemical agent (clear zone around disk representing inhibit of growth) 79 Identify the methods of action and Why is alcohol effective against some preferred uses of chemical disinfectants. viruses and not others? Phenol: control surgical infections in operating Depends if they have a lipid envelope or not room, control odor sewage (now rarely used as disinfectant because of irritation of skin and bad odor) Concentration above 1%= antibacterial effect (Cresols surface disinfectant) Bisphenols: derivative of phenoldisrupt plasma membrane Biguanides: Best one = chlorhexidine Halogens: Iodine and chlorine// effective against antimicrobial agents Alcohols: effectively kill bacteria and fungi, but not endospores and nonenveloped viruses (ethanol and isopropanol) 710 Differentiate halogens used as antiseptics from Is Betadine an antiseptic or a disinfectant when it is halogens used as disinfectants. used on skin? Disinfectant Iodine= antiseptic Chlorine= disinfectant 711 Identify the appropriate uses for What characteristics make surfaceactive agents surfaceactive agents. attractive to the dairy industry? Soap degerming, emulsification Acid anionic sanitizers; very good sanitizing ability Acidanionic sanitizersanions react with plasma membrane Quaternary ammonium compounds (quats) cations are bactericidal, denature proteins, disrupt plasma membrane 712 List the advantages of glutaraldehyde What chemical disinfectants can be over other chemical disinfectants. considered sporicides? Less irritating glutaraldehyde More effective Used to disinfect hospital instruments Sterilizing agent Used in embalming along with formaldehyde 713 Identify chemical sterilizers. What chemicals are used to sterilize? Ethylene oxide Chlorine dioxide Peracetic acid 714 Explain how the type of microbe affects the The presence or absence of endospores control of microbial growth. has an obvious effect on microbial control, but why are gramnegative bacteria more If they are more resistant or not resistant to chemical biocides than grampositive bacteria? Because of their lipopolysaccharide layer Learning Objectives Check Your Understanding 81 Define genetics, genome, chromosome, gene, genetic Give a clinical application of genomics. code, genotype, phenotype, and genomics. West Nile Virus Genetics: study of genes Chromosomes: structures containing DNA that physically carry genetic information, contain genes Genes: segments of DNA that encode functional products, usually proteins Genome: All the genetic information in a cell Genetic code: set of rules that determines how a nucleotide sequence is converted into an amino acid sequence of protein Genotype: genetic makeup Phenotype: expression of genes Genomics: the sequencing and molecular characterizing of genomes 82 Describe how DNA serves as genetic information. Why is the base pairing in DNA important? Gives instructions on how to make things and where they go Important for replication AT GC 83 Describe the process of DNA Describe DNA replication, including the functions replication. of DNA gyrase, DNA ligase, and DNA polymerase. 1. One strand is template for second strand 2. Topoisomerase and gyrase relax strands DNA gyrase: relaxes supercoiling ahead of the replication fork 3. Helicase separates the strands DNA ligase: makes covalent bonds join DNA strands; 4. Replication fork is created Okazaki fragments, & new segments in excision repair 5. DNA polymerase adds nucleotides to growing DNA DNA polymerase: Synthesizes DNA, proof reads, and strand ( 5 to 3 direction) repairs DNA 6. Initiated by RNA primer 7. Leading strand is synthesized continuously and Lagging strand is synthesized discontinuously, creating okazaki fragments 8. DNA polymerase removes RNA primers, fragments are joined by DNA polymerase & DNA ligase 84 Describe protein synthesis, including transcription, What is the role of the promoter, terminator, and RNA processing, and mRNA in transcription? translation. Promoter: where transcription begins when RNA Protein Synthesis: Synthesizing proteins through polymerase binds to DNA in this site translation Terminator: RNA polymerase reaches this site and Transcription: synthesis of complementary mRNA strand gene ends from DNA template mRNA: messenger, carries coded info to synthesize Translation: mRNA translated into “language” of proteins proteins from DNA to ribosomes (codons) RNA processing: genetic info copied and transcribed into complementary RNA sequence 85 Compare protein synthesis in How does mRNA production in eukaryotes prokaryotes and eukaryotes. differ from the process in prokaryotes? Eukaryotes: happens in nucleus Prokaryotes: Uses rRNA (integral part of ribosomes) 86 Define operon. Use the following metabolic pathway to answer the Set of operator and promoter sites and the structural genes questions that follow it. they control enzyme a enzyme b Substrate A Intermediate B Endproduct C a. If enzyme a is inducible and is not being synthesized at present, a (1) _____ protein must be bound tightly to the (2) _____ site. When the inducer is present, it will bind to the (3) _____ so that (4) _____ can occur. b. If enzyme a is repressible, endproduct C, called a (1) _____, causes the (2) _____ to bind to the (3) _____. What causes derepression? 87 Explain pretranscriptional regulation of gene What is the role of cAMP in regulating gene expression in bacteria. expression? Repression and induction Builds up in a cell when glucose is unavailable Binds to lac promoter, initiating transcription 88 Explain posttranscriptional regulation of gene How does miRNA stop protein synthesis? expression. Degrades mRNA microRNAs base pair with mRNA to make it double stranded double stranded RNA is enzymatically destroyed, preventing production f a protein 89 Classify mutations by type. How can a mutation be beneficial? Base (point mutation): change in one base Can be beneficial to antibiotic resistance, helps protect Missense: substitution results in change in amino acid the bacteria Nonsense: sub results in STOP codon Frameshift: Insertion or deletion of one or more pairs 810 Describe two ways mutations can be repaired. How can mutations be repaired? Photolyases enzymes that use visible light energy to separate the dimer back to 2 original thymine Nucleotide excision repair cut out incorrect base & fill in the gap 811 Describe the effect of mutagens on the mutation How do mutagens affect the mutation rate? rate. Enhance it Mutagens usually increases the spontaneous rate of mutation, 10 to 1000 times. 812 Outline the methods of direct and How would you isolate an antibioticresistant indirect selection of mutants. bacterium? An antibioticsensitive bacterium? Positive direct selection: involves the detection of mutant cells by rejection of the unmutated parent cells Negative indirect selection: selects a cell that cannot perform a certain function using a technique called replica plating 813 Identify the purpose of and outline the procedure What is the principle behind the Ames test? for the Ames test. Based on observation that exposure of mutant bacteria Uses bacteria as carcinogen indicators to mutagenic substances may cause new mutations that reverse the effect of the original mutation 814 Differentiate horizontal and vertical gene transfer. Differentiate horizontal and vertical gene transfer. Vertical: genes passed from an organism to its offspring Horizontal: can pass to offspring, but also to other microbes of same generation 815 Compare the mechanisms of genetic recombination Compare conjugation between the following pairs: in bacteria. F F , Hfr F . Genetic Recombination: exchange of genes between 2 DNA molecules to form new combinations of genes on a chromosome 816 Describe the functions of plasmids and What types of genes do plasmids carry? transposons. Genes for sex pili Plasmids: often code for proteins that enhance the pathogenicity of a bacterium Transposons: contain insertion sequences that code for transposase that cut and reseals DNA 817 Discuss how genetic mutation and Natural selection means that the environment recombination provide material for natural favors survival of some genotypes. From where does selection to act upon. diversity in genotypes come? They create cell diversity which is raw for evolution and natural selections acts upon populations of organisms to ensure survival
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