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Microbiology
Celebration 3 Material
| Question | Answer |
|---|---|
| Lytic replication steps (virus) | 1. Attachment 2. Penetration 3. Replication 4. Assembly 5. Release (via lysing of bacterial cell) |
| Lysogenic replication | After penetration, the phage's DNA is directly integrated into host chromosome, making a prophage. Now as host cell replicates it will also replicate the virus's DNA with its own. |
| Prophage | In lysogenic replication, when virus (bacteriophage) DNA is integrated into the host cell's |
| Animal virus replication | 1. Attachment 2. Penetration (endocytosis if naked virus, fusion if enveloped) 3. Uncoating (genome released from capsid) 4. Replication (genome, then proteins are made) 5. Assembly 6. Release (budding if enveloped virus, lysis if naked) |
| Because animal cells have no cell wall, they _____ have to lyse to release viruses. | Do not |
| How does a naked virus penetrate an animal cell? | Endocytosis |
| How does an enveloped virus penetrate an animal cell? | Fusion |
| How is a naked virus released in an animal cell? | Lysis |
| How is an enveloped virus released in an animal cell? | Budding |
| Virus replication in acute infections | Spike in viral replication until body/host mounts effective immune response--then viral load drops rapidly. 10-14 days |
| Virus replication in persistent, chronic infections | Low replication, viral load slowly increases over time until it overwhelms system Ex: HIV |
| Virus replication in persistent, latent infections | Outbreaks occur (looks like an acute infection at each outbreak, then nothing until the next outbreak) Ex: Herpes, chicken pox |
| Example of persistent, chronic infection | HIV |
| Example of persistent, latent infection | Herpes, chicken pox |
| Replication of HIV | 1. Attachment and penetration 2. Uncoating 3. Reverse transcription (retrovirus)- makes viral DNA from RNA 4. Viral integration- inserts DNA into host 5. Replication, assembly, and release |
| ______ percent of cancers are caused by viruses. | 10-15% |
| Oncogenic viruses | Viruses linked to cancer. Cause "transformation of cell" Ex: HPV - ovarian cancer |
| Sensing viral proteins diagnostic method | 1. Where antibodies are attached to a bead and seeing if anything happens when injected (like agglutination) |
| Sensing patient's antibodies diagnostic method | Virus is attached to bead and mixed with plasma from the patient, see if anything happens, and if it does that means the patient has antibodies and has the virus |
| Identifying viral genetic material diagnostic method | Is more sensitive and very specific for finding out if a patient is affected, but is not rapid |
| Specificity | Will only bind to virus. You don't get false positives, but as sensitivity lessens you will get more false negatives |
| Sensitivity | Being able to detect target at low concentrations (false positives possible, but false negatives less likely) |
| Difficulties in designing antiviral drugs: | 1. Viruses are obligate intracellular pathogens (uses host's machinery, so can't attack that) 2. Antivirals should be relatively toxic 3. Viruses have fewer chemically distinct targets than living cells |
| HRIG | Effective antiviral agent for rabies, blocking attachment to host cells |
| Tamaflu | Effective antiviral agent against influenza, blocking release of new viruses (so if you take it early will keep you from getting really bad). |
| When there is sufficient nutrients, a microbe will ______ and eventually _____. | Enlarge, divide |
| Binary fission steps | 1. Chromosome is replicated 2. Parent cell begins to pinch off at middle 3. Partition (septum) in center becomes complete 4. Creates 2 genetically identical daughter cells |
| Generation time | Time needed for one generation to be produced. Total time elapsed/number of generations generated. |
| Typical growth curve of bacterial population | 1. Lag phase 2. Log phase (exponential) 3. Stationary phase 4. Decline phase and cryptic growth |
| Batch culture | Bacteria grown in a controlled environment with a certain amount of nutrients. Ex: Test tube |
| Lag phase | Phase in bacterial batch growth where there is little growth, as the microbes are adjusting to their environment through GENE EXPRESSION |
| Log phase | Phase in bacterial batch growth where binary fission is occurring at optimal rate in that environment (sharp increase in population) |
| Stationary phase | Phase in bacterial batch growth where the cells are not actively dividing nor dying, caused by the decrease in nutritional concentrations and increase in waste and cell density. |
| Stationary phase is due to: | Decrease in nutrients, increase in cell density and waste |
| Decline phase | Phase in bacterial batch growth where some cells start to die. Is interrupted for short periods by cryptic growth |
| Cryptic growth | Phase in bacterial batch growth in the decline phase where as cells die, their nutrients are cannibalized by other microbes, allowing little spurts of binary fission to occur |
| At low temperatures, microorganisms | Have membrane gelling, transport is so slow across it no growth occurs |
| At medium temperatures, microorganisms | Have enzymatic reactions occur at increasingly rapid rates as temperature increases |
| At optimum temperatures, microorganisms | Have enzymatic reactions occurring at maximum optimal rates |
| At high (max) temperatures, microorganisms | Have protein denaturation. Thermal lysis occurs as cell membrane collapses |
| Psychrophile | From below freezing (0 C) to 15 C. Middle is about 4 CProteins and plasma membrane have weaker bonds to increase fluidity |
| Mesophile | From around 10 C to 45 C, middle being 39 C. |
| Thermophile | From 42 C to 68 C, middle being 60 C. |
| Hyperthermophilic | From 65 C to 97 C, middle being 88 C. |
| Hyperthermophile | From 90 C to 115 C. |
| Molecular adaptations to life in cold temperatures | Proteins and membranes with weaker bonds to increase fluidity |
| Molecular adaptations to life in hot temperatures | Proteins with stronger bonds, and a more rigid plasma membrane to withstand heat |
| Three classifications of microbes according to pH | Acidophile, neutralophile, alkaliphile |
| What is the internal pH of an acidophile? | Neutral (6-8 pH) |
| What is the internal pH of an alkaliphile? | Neutral (6-8 pH) |
| Typically, the cytoplasm has a ____ solute concentration than the surrounding environment. | Higher |
| Water activity | Relative humidity. Pure water =1, as salt concentration increases this decreases. Gram positive can usually tolerate salt a little (0.95) |
| Osmosis | |
| Water availability | |
| Nonhalotolerant | Has no tolerance for salt concentration |
| Halotolerant | Has a little tolerant for salt, good growth still at near 0 %, but grows a little until about 10% concentration |
| Halophile | Likes salt, good growth around 5-8% concentration |
| Extreme halophile | Loves salt, will being growth at about 12% concentration and has best growth at 18% or more. |
| Osmophiles | Needs a high concentration of solute, but the solute doesn't have to be salt |
| Xerophiles | Things that can exist in a low water environment no matter the salt concentration. |
| Molecular oxygen ____ toxic. | Is |
| Three common toxic byproducts of O2 reduction | Hydrogen peroxide (H2O2), superoxide (O2-), hydroxyl radical (OH.) |
| Catalase | Enzyme for destroying H2O2 into water and O2 |
| Peroxidase | Enzyme for destroying H2O2 into water and NAD- |
| Superoxide dismutase | Enzyme that destroys superoxide (O2-) into H2O2 and O2. |
| Obligate aerobes | Requires O2, does only aerobic respiration |
| Facultative | Oxygen is not required, but grows better with it. Can do aerobic respiration, anaerobic respiration, and fermentation |
| Microaerophilic aerobes | Oxygen is required but only at levels lower than atmospheric. Does aerobic respiration |
| Aerotolerant anaerobes | Oxygen is not required and growth is not improved with its presence. Does fermentation |
| Obligate anaerobes | Oxygen is harmful/lethal. Does fermentation and/or anaerobic respiration |
| Three classifications of microbial media | Physical nature, chemical constituents they are made from, function |
| Defined media | Type of media where the exact chemical composition is known |
| Complex media | Type of media composed of digests of microbial, animal, and plant products (like extracts) |
| Selective medium | Type of media that has compounds that selectively inhibit growth of some microbes and not others |
| Differential medium | Type of media that contains an indicator dye that detects specific metabolic reactions during growth |
| Peptones | Complex media of digests of proteins (beef extract, pork extract, etc.) |
| Extracts | Where you put things into a pot and brew it to gain the nutrients from it. |
| Can media be differential and selective? | |
| What role do aseptic techniques play in health care? | Routine part of patient care with injections or collecting clinical samples for analysis. Also prevents introducing infectants |
| What is the goal of isolating microbes using the streak plate techniques? | IDENIFYING potential pathogen in clinical sample |
| Direct microscopic counting | Uses a counter that you put a drop of sample on a small grid. You count the microbes inside the grid and them calculate concentration per milliliter of sample |
| Limitations of direct microscopic counting | Can't tell if cells are living or dead, isn't good for dilute solutions, and is also bed for cells that clump together, and therefore make it hard to count accurately. |
| Spread-plate method | Viable count method where you sample pipet onto an agar plate and spread it evenly, then incubate and count the colonies |
| Pour-plate method | Viable count method where you put sample in empty plate and then add liquified agar and mix well, then incubate and count. |
| Colony-forming unit | The beginning cell that will form a colony with nutrients |
| Great plate count anomaly | Sometimes bacteria just won't grow, no matter if you know there are living bacteria on your plate. It occurs because some microbes require certain environments we can't replicate. |
| How to find original concentration of colony forming units in a bacterial suspension | Original concentration= # CFUs counted on plate / (volume plated times dilution factor). Units is CFUs per mL |
| How is optical density measured? | Spectrophotometer |
| Unit of optical density | OD with specified wavelength number as subscript. |
| In order to relate a direct cell count to a turbidity value, what must first be established? | Serial dilution to establish where it should be as a standard curve |
| Optical density | Turbidity measurement of microbial growth. Is fast, and you can do multiple, however you cannot tell if cells are living or dead. |
| Methods for identifying microbes: | 1. Physical analysis- staining and microscopy 2. Biochemical analysis- a collection of media used to assess metabolic properties 3. Genetic methods- quickly identifies microbes using probes, DNA "fingerprint", etc. |
| Decontamination | Removes/reduces microbial populations to render object safe for wearing. |
| Sterilization | Eliminates all bacteria, viruses, and endospores. Requires drugs, used for mainly medical instruments that are metal or glass (must be heat tolerant), is the fastest, and is harshest. |
| Disinfection | Reduces microbial numbers. Used for cosmetics, foods, surfaces, external medical equipment. Usually for things too big/wrong material for sterilization, takes longer though. |
| Antisepsis | Chemicals applied to BODY SURFACES to destroy/inhibit vegetative pathogens. Takes longer than most to work |
| Sanitization | Treatment of inanimate object to lower microbial counts on EATING/DRINKING UTENSILS |
| Gemicide | Kills germs |
| Physical agents category of microbial control | Heat (dry or moist) and radiation (ionizing or nonionizing) |
| Chemical agents category of microbial control | Gases and liquids |
| Mechanical removal category of microbial control | Filtration (of air or liquids) |
| Biological agents category of microbial control | Predator, virus, and toxins |
| Bacteriostatic | Antibacterial agent classification that inhibits growth but doesn't kill microbes. Ex: cold |
| Bactericidal | Antibacterial agent classification that kills microbes, but the total cell count doesn't go down as the dead cells are still able to be seen |
| Bacteriolytic | Antibacterial agent classification that lyses the cell to kill it. Both number of viable cells and total cell count seen decreases |
| Decimal reduction time (D) | Amount of time required at given temperature to reduce VIABILITY by 90% |
| Facts about decimal reduction time | 1. It is an exponential relationship 2. Heat kills cells faster as temperature rises 3. Moist heat penetrates better than dry (hand into water gets more hurt than hand into hot oven air) |
| Thermal death time | Shortest period of time needed at certain temperature needed to kill all microbes in a sample |
| Thermal death point | Minimum temperature needed to kill all microbes in a sample within 10 minutes |
| Autoclave | Machine that applies steam heat and pressure to sterilize (denatures proteins). Disadvantages: Not for moisture/heat sensitive materials |
| Dry heat | Incineration or hot-air used to denature proteins and sterilize things. Advantages: Super fast Disadvantages: Anything heat sensitive is destroyed |
| Pasteurizaiton | Disinfection of pathogens and spoilage microbes. Heats liquid for a time to denature their proteins. Disadvantages: Changes flavor, fat content, and texture of products |
| Ultra violet (UV) radiation | Nonionizing radiation of UV rays to cause mutations in genetic material to render it unable to grow. Disadvantage: Has low penetration of material Advantage: More easy to come by than ionizing, leaves no residue |
| Ionizing radiation | Gamma or X-rays to cause mutations in genetic material. Advantage: Leaves no residue, has high penetration, and can treat heat/moisture sensitive materials Disadvantage: Living things harmed more severely than with UV |
| Why might filtration be advantageous to heat or chemical sterilants? | Physically removes microbes from material, good for large areas. for liquids and gases, and can be used with heat sensitive materials |
| Depth filter | Thick filters of many layers of webbed sheets to trap particles. Doesn't trap most viruses. |
| Membrane filter | Most common for liquid sterilization, high-strength polymers with many tiny pores that the material is forced through via pump/syringe |
| What are the limitations of filtration? | Can let viruses through, as they are so small |
| Low-level agents | Germicide that kills gram +/- and growing bacteria and enveloped viruses |
| Intermediate-level agents | Germicide that kills acid-fast bacteria and naked viruses |
| High-level agents | Germicide that kills endospores |
| Critical equipment | Decontamination of medical equipment that will touch sterile areas of the body. Must be sterilized |
| Semi critical equipment | Decontamination of medical equipment using high level disinfection agents. Touches mucous membranes or non-intact skin. Ex: Nasal swab and tongue depressor |
| Noncritical equipment | Decontamination of medical equipment using low/intermediate level disinfection. They will come in contact with human skin Ex: stethoscope, blood pressure cuff |
| Alcohols | Dissolve plasma membrane. Doesn't dehydrate skin much and leaves no residue as it evaporates quickly. Good for enveloped viruses and bacteria but not naked viruses. |
| Aldehydes | Pretty toxic, can be chemical sterilant. Combines and inactivates nucleic acids and proteins. Leaves a residue |
| Phenol/phenolics | Denatures proteins and disrupts cell membranes. Skin/respiratory irritant that leaves a residue that must be washed off. Disinfects and needs time to effectively kill. Household cleaners, can cause endocrine disruption (BPA) |
| Halogens | Great oxidizer of cellular components. Used for water purification. Better than alcohol because leaves a residue to keep killing, but can irritate because of it. |
| Heavy metals | Percipitates proteins and replaced enzymes to render them ineffective. Bacteriostatic, usually in manufactured materials to limit bacteria growth |
| Peroxygens | High level germicide with strong oxidizing properties. Kills most microbes, good for solids and not for liquids. |
| Sterilizing gases | Can be used with heat/moisture sensitive materials and is pretty toxic. Good with solids, not with liquids (must bubble into it) |
| Detergents and Quaternary Ammonium Compounds | Denatures proteins, used as sanitizing agent (dish washing and hands). Doesn't work well with a lot of organic material around (like dirt) |
| Factors to consider when selecting germicide | 1. Item uses 2. Germicide reactivity (with it destroy item?) 3. Germicide concentration/treatment times 4. Types of infectious agents to control (viruses, bacteria, etc.) 5. Presence of organic material 6. Impact of residue 7. Toxicity |
| Difficulty to kill microbe: | Most to least 1. Endospores 2. Nakes viruses 3. Enveloped viruses 4. Mycobacteria (acid fast) 5. Stationary cells 6. Vegetative cells (gram negative, then gram positive) |
| Mycobacterium control is ______ hard. | Very |
| Endospore control is _____ hard. | Very |
| Viral control is _____ hard. | Somewhat, can be deactivated |
| Protozoan control is _____ hard. | Not |
| MIC (Minimum inhibitory concentration) | Lowest concentration that will inhibit bacterial growth |
| Minimum lethal concentration (MLC) | Lowest concentration that will kill the microbial environment |
| Disk diffusion assay on solid media | Grow bacteria on plate, place discs infused with different concentrations of antimicrobial agents and view zones of growth inhibition. |
| Units of original concentration of colony forming units in bacterial suspension. | CFUs/mL |
Created by:
RunningMads
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