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Exam 1 Microbiology
| Question | Answer |
|---|---|
| What is microbiology? | the study of microorganisms, small life that is too small to be seen with the naked eye (in general) |
| What are the six different organisms that microbiologists study? | bacteria (pro), algae, protozoa, worms (eu), viruses (acellular) |
| What are the two main reasons we need microbes? (for the planet) | 1. Decomposition - nutrient recycling for elements (dead organic material), 2. Photosynthesis - 70% performed by microbes |
| Name some human uses for microorganisms. | 1. food/beverage production (mold - cheese, yeast - bread, alcohol)2. viruses to make vaccines, 3. genetic engineering,4. sewage treatment, 5. oil spill cleanup (bioremediation) |
| Why is there a higher instance of communicable disease death in lower income countries? | less access to healthcare (vaccines, hospitals, medications), poor diet = lower immunity, unsanitary conditions (water), education, denser population |
| What is an emerging disease? A re-emerging disease? | Emerging - new, seen for the first time Re-emerging - prevalent at one time, numbers dropped, now the numbers are rising again |
| Explain what the quote "Organisms changed and people changed," means | Microbes evolved - gained resistance to treatments (MRSA) People evolved - travel (easy to spread things worldwide, new pathogen contact to different people), mutation (move from organism to organism H1N1) |
| What are some things that may be related to microbial infection? | Obesity, gastric ulcers (bacteria), some cancers (HPV), diabetes, schizophrenia, MS, OCD, CAD |
| How is the fact that some things may be related to microbial infection medically significant? | If they are all caused by microbes, then we may eventually be able to make a vaccine for these aliments. |
| Why did the study of microbiology begin with the invention of the microscope? | "Seeing is believing" - most microoganisms are not visible to the naked eye, you cannot study something that you cannot see - Robert Hooke invented microscope |
| What is PCR? | amplifies DNA so that i can be studied |
| What is a small RNA? | Small RNAs are all RNA not used to make proteins - they are used in cellular regulation and open the door for a means to control a prokaryote |
| What is a biofilm? | a community of microbe prevalent in the human body |
| Give an example of a biofilm. | plaque on teeth |
| What is spontaneous generation? | the belief that life can arise from something that is not living (abiogenesis) - Ex: meat left out "produces" maggots |
| Who disproved spontaneous generation? How? | Louis Pasteur - developed the swan neck flask (chicken broth experiment) |
| What else did Louis Pasteur do? | determined the role of microbes in fermentation: yeast + grape juice = alcohol, bacteria + grape juice = acid |
| What is pasteurization? | the use of heat to control growth; kills primary pathogens but does not sterilize |
| What is sterilization? | the process of rendering something completely free of all life forms |
| What is an autoclave? | a machine used for sterilization (120 degree C heat + pressure from steam = sterilization) |
| Is boiling enough to sterilize something? | No |
| Aseptic techniques | steps to minimize contamination (handwashing) |
| Who was the first to observe the connection between hand-washing and disease prevention? | Joseph Lister |
| What is the Germ Theory of Disease? | The acceptance that infectious diseases are caused by microbes developed by Robert Koch in 1875 |
| What is a binomial nomenclature system? | The system of assigning something a scientific name using genus + species |
| What three principles are the basis of medical microbiology? | Sterilization, Aseptic Techniques, The Germ Theory of Disease |
| What is a pathogen? | disease causing microbes: neary 2000 different types |
| Describe the ubiquity of microbes. | Microbes can be found nearly everywhere: deep in Earth's crust, polar ice caps, oceans, bodies of plants and animals |
| How are genetically modified organisms designed? | Recombinant DNA technology |
| What is recombinant DNA technology? | makes it possible to transfer genetic material from one organism to another and to deliberately alter DNA |
| What are characteristics that solely belong to prokaryotes? | endospore, pili, nucleoid |
| What are characteristics that solely belong to eukaryotes? | mitochondria, ER, nucleus |
| Who is Anton von Leeuwenhoek? | A dutch linen merchant who is considered the father of Microbiology - began by looking at thread under the microscope then described small animals that seemed to be living on things |
| What are the essential structures that all prokaryotic cells possess? | cell membrane, cytoplasm, ribosomes, 1 or a few chromosomes (genetic material) |
| What are three ways to distinguish a prokaryote from a eukaryote? | No true nucleus (the way its DNA is packed), the sturdier makeup of its cell wall, its internal structure (no membrane bound organelles) |
| What are the two types of external structures on prokaryotic cells? | appendages and glycocalyx (capsule) |
| What is the function of the appendages? | motility, protection, attachment |
| Name the three types of appendages? | flagella, pili, fimbriae |
| Describe flagella. | may have one or more, classified based on where they are attached (chemotaxis or phototaxis) |
| What is the purpose of flagella? | motility - can move away from harmful things or towards beneficial things |
| Describe pili | usually only one "pilus" - purpose is attachment |
| What does a pilus allow bacteria to do? | allows bacterial cells to attach ot another bacterial cell for gene exchange (conjugation) |
| What is the purpose of fimbriae? | allows a cell to attach to a surface |
| Give an example of a type of bacteria that needs fimbriae. | E. Coli needs fimbriae to attach to the urethra to cause a UTI |
| Which two types of appendages are only found in bacterial cells? | fimbriae and pili |
| What are the two main purposes of the glycocalyx? | 1. Protection: from human defenses (phagocytes cannot bind to capsule), against loss of water and nutrients, 2. Attachment: to surfaces primarily (helps make biofilms - stick to other bacteria and then to a surface) |
| On what types of surfaces do biofilms form? | organic layer that is moist |
| What is the first phase of biofilm formation? | initial bacteria attach to surface using fimbriae or capsule/glycocalyx |
| What is the second phase of biofilm formation? | Once the initial bacteria attach, more cells begin to attach to those, bacterial cells communicate with one another which is important for fcn: #s begin to increase in given area and cells begin to express diff. genese |
| What is the third phase of biofilm formation? | Begin making extracellular matrix (ECM) which is made up of different types of microbes |
| What is a mature biofilm? | a diverse community of microbes surrounded by an ECM |
| Where might biofilms form in the body other than on the teeth? | ears (chronic ear infection), damaged tissue, artificial implants into body (hip replacements), lungs in cystic fibrosis, IUDs, catheters, breathing tubes (contributes to nosocomial infection) |
| Why are diseases related to biofilm formation hard to treat? | 1. altered gene expression = more antibiotic resistance, 2. diverse community of microbes make it a hard target, 3. ECM acts as a shield and can be very hard to penetrate |
| What are the three layers that make up the cell envelope? | outer membrane, cell wall, cell membrane |
| What is the prokaryotic cell wall composed of? | peptidoglycan |
| What function does the cell wall perform in bacterial cells? | structural support necessary to keep a bacterium from bursting or collapsing b/c of changes in osmotic pressure |
| Prokaryotic boundary structures are important in distinguishing between _____ and _______ bacterial cells. | gram positive and gram negative |
| How many layers of boundary structures do bacterial cells have? | 2 or 3 |
| Where does the electron transport chain reside in prokaryotic cells? | the cell membrane |
| What is the main difference between a gram positive and a gram negative cell? | gram positive = 2 layers (cell membrane and cell wall), gram negative = 3 layers (cell membrane, cell wall, and outer membrane) |
| Describe the cell wall of a gram positive cell. | composed mainly of a thick layer of peptidoglycan (2 subunits), cross-linked molecules between the layers which help make it strong, also contains techoic acid |
| What is techoic acid? | a component of gram positive cells only, attaches to cell membrane or peptidoglycan |
| Can a gram positive cell regulate what enters and exits the cell? | no - the cell wall is only for strength and protection (osmotic pressure) |
| Gram negative cells also have peptidoglycan in their cell wall. How does the cell wall differ from a gram positive cell? | very thin layer, very little cross-linking if any |
| The outer membrane of a gram negative cell is a ____________. | phospholipid bilayer |
| What is a lipopolysaccharide? | a polysaccharide tail that extends to the exterior of the cell located on the outer membrane of some gram negative cells |
| What is the significance of an LPS? | as long as it is part of an intact cell our defenses do not respond to it but when a cell dies then the LPS is released and the LPS is toxic and can result in death |
| What is on the outer membrane that anchors it to the cell wall? | lipoprotein |
| What is a porin? | a transport protein that spans the entire width of the outer membrane of gram negative cells; much like a straw with an open middle |
| Can a gram negative cell control what goes in and out? | Yes, the outer membrane is selectively permeable much like a cell membrane. |
| What are the two exceptions to the cell wall rule? | mycobacterium (TB) and mycoplasma |
| What is unique about a mycobacterium? | it is a gram positive cell that contains mycolic acid which provides a unique characteristic for this genus |
| What is unique about mycoplasma? | 1. primarily one species that is a human pathogen (walking pneumonia), 2. the only genus of prokaryotes that has no cell wall, 3. has sterols in the cell membrane that provide protection in structure (in lieu of cell wall) |
| What does the antibiotic penicillin target? | cell walls of prokaryotes: since the cell wall of the prokaryote is different than the cell wall of eukaryotes, human cells aren't harmed |
| Is penicillin more effective against gram negative cells or gram positive cells? | Only effective against gram positive cells because it specifically targets cross-linking |
| Does penicillin actually kill gram positive cells? | No, just weakens their cell walls so that osmosis kills the bacteria b/c bacteria are hypotonic to human cells so water rushes in and causes the cell to lyse |
| How do you kill a gram negative cell? | target the outer membrane instead of the cell wall - since alcohol dissolves lipids of a cell it is more effective against gram negative |
| Why aren't antibiotics as effective in killing gram negative cells? | outer membrane blocks their entry into the cell |
| If a person with an infection caused by a gram negative bacteria is treated with an antibiotic that is successful in killing the bacteria, why might the person's symptoms get worse? | Killing the cells allowed the LPS to be released which is toxic |
| What are the prokaryotic internal structures? | cytoplasm, ribosomes, nucleoid, and possibly an endospore |
| What function do ribosomes serve in prokaryotic cells? | manufacture proteins |
| Where are ribosomes found? | in the cytoplasm |
| What is the difference between prokaryotic ribosomes and eukaryotic ribosomes? | size: pro = 70s and eu = 80s |
| How is this difference significant when treating infections caused by prokaryotic cells? | You can safely target 70s ribosomes without the fear of harming the eukaryotic organisms' 80s ribosomes. |
| Describe the nucleiod. | 1. genetic material of prokaryotes, 2. single circular molecule of DNA represented by a figure 8, 3. also have plasmids which provide nonessential genetic material |
| What is sporulation? | the process of making one endospore |
| What types of cells make endospores? | metabolically active vegetative cells (only gram positive) |
| How is an endospore made? | chromosomes are replicated and many layers are placed around a chromosome to make an endospore |
| What are the three genus that make endospores? | Bacillus, Clostridium, and Sporasarcina |
| What are three conditions caused by endospores? | Gas gangrene and tetanus vegetative cells (clostridium) and cutaneous anthrax (Bacillus |
| Why is an endospore made? | they are a survival strategy that helps bacterial cells to withstand harsh environments (extreme temperatures, too dry, harsh chemicals, lack of nutrients) |
| What is germination? | The process by which the endospore state is reversed upon a return to favorable conditions. |
| Bacteria are classified based on shapes and arrangements. Name and describe the 5 shapes. | cocci (round/spherical), bacilli (rod-shaped), vibrio (comma), spirilli (corkscrew), spirochete (slinky) |
| What are the four ways in which cocci bacteria can be arranged? | diplococci(2 cells stuck together), tetrads (4 cells stuck together), streptococci (chains), staphylococci (clusters/"grapes") |
| What are the two ways in which bacilli can be arranged? | diplobacilli (in pairs) and streptobacilli (in chains) - never as tetrads or clusters! |
| Describe vibrio shape. | rod-shaped bacterial cell that has a slight curve |
| Describe the spirilli shape. | rod-shaped cell and twisted on each end, very stiff and not flexible |
| Describe the spirochete shape. | rod-shaped cell that is twisted, but is flexible |
| Who proposed the term virus and developed the first vaccine for rabies in 1884? | Louis Pasteur |
| Do viruses always cause harm? | No, but always genetically modify (tulip) |
| What are three uses of viruses in treatment and prevention of diseases? | 1. vaccines to treat viral infections (flu, polio, measles), 2. oncolytic virotherapy, 3. bacteriophages - treat bacterial infections |
| Property of Viruses (POV) #1: obligate intracellular parasites of: | bacteria, protozoa, fungi, algae, plants and animals |
| POV#2 | are not cells |
| POV#3 | do not independently fulfill characteristics of life |
| POV#4: consists of nucleocapsid = | protein shell (outer) capsid surrounding nucleic acid (genetic material) in the core |
| POV#5 Genetic material may be: | DNA or RNA, single or double stranded, circular or linear |
| POV#6 Specificity | Molecules on the virus surface impart a high specificity for attachment to host cell |
| POV#7 | Multiply by taking control of the host cell |
| What are the components of a virus from most exterior to most interior? | 1. Envelope (optional), 2. Capsid, 3. Genetic Material, 4. Proteins, enzymes (optional) |
| What are spikes? | some viruses have spikes on their envelope which are important to the virus if they're present b/c that is how the virus attaches to its host cell (similar to how receptors work) |
| What is the capsid made of? | protein |
| Can a virus bind to its host cell if it does not have spikes or an envelope? | yes |
| What are the 6 stages of active replication in animal viruses? | adsorption, penetration, uncoating, synthesis, assembly, release |
| What is adsorption? | the virus encounters a susceptible host cell and adsorbs specifically to receptor sites on the cell membrane |
| How does adsorption differ between enveloped viruses and noneveloped viruses? | Enveloped - glycoprotein spikes bind to the cell membrane, Nonenveloped - uses molecules on their capsids to bind to cell membrane receptors |
| What happens during penetration? | entrance into the host cell by the whole virus or its nucleic acid |
| Penetration enveloped vs nonenvelopled? | Env = endocytosis or membrane fusion, Non = endocytosis only |
| What happens during uncoating? | all layers of material enclosing viral genetic material must be degraded/broken down - once this step is complete, the genetic material is free in the cytoplasm of the host cell and the host cell is virally infected at this point |
| What happens during synthesis? | creation of individual parts of the virus, genetic material is copied |
| What happens during Assembly? | individual parts of the virus are put back together, genetic material is put into capsids |
| What happens during release? | Nonenveloped cell - released by lysis, Enveloped cell - released by budding (host cell dies either immediately or slowly) |
| Define host range. | viruses can only invade host cells that are an exact fit for the virus (specificity) (host cell species) (attachment site) |
| Where do RNA viruses multiply? DNA viruses? | RNA - cytoplasm, DNA - cell nucleus |
| Latency | dormant phase of virus where it is not actively replicating Ex: herpes - not always inflamed |
| What are two ways that damage is done to host cells? | cytopathic effects and mutation |
| What are cytopathic effects? | virus-induced damage to the cell that alters its microscopic appearance |
| What can happen to a cell as a result of cytopathic effects? | disorientation of cell, gross changes in shape or size, develop intracellular changes, presence of inclusion bodies |
| Why is it important to observe the cytopathic effects of certain viruses? | diagnoses in a medical situation |
| What is a mutation? | when viral genetic material permanently alters host cell genetic material which may lead to cancer (oncogenic virus = oncovirus) |
| What are some examples of oncogenic viruses and the conditions they cause? | Herpesvirus - Burkitt's lymphoma, HPV - cervical cancer, Hep B - liver cancer, FeLV - leukemia in cats |
| What is oncolytic virotherapy? | virus cells that target and kill tumor cells without harming normal cells |
| Are antibiotics effective in treating viruses? | No b/c they are not prokaryotic cells |
| What is a bacteriophage? | A virus that attacks bacteria |
| The lytic cycle of bacterophage is similar to the active phase of an animal cell. What are some key differences? | 1. penetration happens when nucleic acid is directly injected into the host cell through a rigid tube, 2. there is no uncoating step because of this 3. duplication, assembly, maturation, lysis and release |
| What is the lysogenic phase? | similar to the latent phase of animal viruses, virus does adsorption and penetration but then integrates the chromosome with the viral genetic material and becomes a prophage |
| What happens to the prophage? | bacterial cell carries on all of its normal functions but is virally infected, gets duplicated during normal cell division of bacteria, can exit lysogenic state by means of induction back to lytic state |
| What is a temperate phage? | one that can exist in both the lytic and lysogenic phase |
| Why can't a bacteriophage form in the lysogenic cycle? | bacteriophage can only be replicated but to be reassembled and continue to release, it must be in the lytic phase. Lysogenic phase = complete dormancy |
| What is lysogenic conversion? | when a bacterium acquires a new trait from its temperate phage |
| Why is this medically significant? | host cells are converted to a new genetic strain; some bacteria can only cause infection when the bacterial cell has been virally infected |
| What are some examples of diseases caused by lysogenic conversion? | 1. Diptheria (viral genetic material makes the toxin that causes the illness), 2. Scarlet fever (Streptococcus pyogenes) - can always cause strep throat but when it is virally infected = Scarlet fever, 3. Cholera |
| What do prions cause? | spongiform encephalopathies - brain becomes a sponge; damages the tissue to create holes |
| What are some examples of spongiform encephalopathies? | Kuru, scrapie(sheep), Mad Cow Disease (BSE), vCJD, chronic wasting disease |
| How are prions transmitted? | ingestion of contaminated brain or spinal tissue |
| What are the symptoms of spongiform encephalopathies? | mental derangement and loss of muscle control - progressive and always fatal |
| What are prions composed of? | protein only |
| How do prions accumulate? | proteins normally found in the brain have a gene for the normal protein which is similar to prion sequence so it combines and then replicates the new combined sequence |
| Prion initiates the conversion of __________ and ____________ increases. | normal proteins, exponentially |
| Can a person get prions without ingesting contaminated materials? | Yes, genetic mutation also causes spongiform encephalopathies |
| What is the main component of microbial cytoplasm? | water |
| What are essential nutrients? | a substance that a cell cannot make on its own and must be provided |
| 96% of a cell are made of up 6 elements: (also examples of essential nutrients) | Carbon(organic or inorganic), Nitrogen, Oxygen, Hydrogen,Phosphorus, Sulfur |
| Nutritional types are based on: | energy source and carbon source |
| Most bacteria that cause infection in humans are ___________. | chemoautotrophs (inorganic chemicals = energy source) (CO2 = carbon source) |
| chemotroph | inorganic chemicals or organic chemicals = energy sourch |
| autotroph | carbon source = CO2 |
| phototroph | energy source = light |
| heterotroph | carbon source = organic chemicals |
| What are the steps of binary fission? | 1. a young cell, 2. chromosome is duplicated and old and new chromosome move to separate sides of cell, 3. protein band forms in center, 4. Septum formation begins, 5. division or stick together |
| What is generation time? | how long it takes for one binary fission event to occur, varies from bacterial organism to bacterial organism |
| The bacterial growth curve is based on what kind of scale? | log scale |
| In a fixed environment, what are the four stages of progression of a bacterial population? | 1. lag phase, 2. exponential growth phase (log phase), 3.Stationary phase, 4. Death phase |
| What are three environmental factors affecting growth? | Temperature, oxygen, pH |
| What is cardinal range? | the minimal, optimal, and maximal temperature for survival |
| What is plasmolysis? | the shrinking of cytoplasm away from the cell wall due to water loss (immersion into hypertonic solution) which creates gaps between the cell wall and cell membrane |
| Psychrophile | A microorganism that thrives at low temperature (0°C–20°C), with a temperature optimum of 0°C–15°C. |
| Mesophile | Microorganisms that grow at intermediate temperatures. |
| Thermophile | A microorganism that thrives at a temperature of 50°C or higher. |
| Aerobe | A microorganism that lives and grows in the presence of free gaseous oxygen (O 2 ). |
| Facultative anaerobe | Pertaining to the capacity of microbes to adapt or adjust to variations; not obligate. Example: the presence of oxygen is not obligatory for a facultative anaerobe to grow. |
| Anaerobe (obligate) | an obligate aerobe must have oxygen to grow; an obligate anaerobe is destroyed by oxygen. |
| Anaerobe (aerotolerant) | The state of not utilizing oxygen but not being harmed by it. |
| microaerophile | An aerobic bacterium that requires oxygen at a concentration less than that in the atmosphere. |
| Capnophile | microorganisms that thrive in environments with high concentrations of carbon dioxide |
| Superoxide | A toxic derivative of oxygen; (O 2 − ). |
| Superoxide dismutase | first step in converting superoxide to harmless oxygen makes superoxide into hydrogen peroxide and normal oxygen since hydrogen peroxide is toxic to cells it must then be degraded |
| Catalase | converts hydrogen peroxide into water and oxygen |
| What is the preferred pH of bacteria? | 6-8 |
| Symbiotic | organisms live in close nutritional relationships; required by one or both members |
| What are the three subsets of symbiotic relationships? | mutualism, parasitism, and commensalism |
| Mutualism | obligatory dependent (+,+) |
| Parasitism | parasite is dependent, host harmed (+,-) |
| Commensalism | The commensal benefits, other not harmed (+,0) |
| Nonsymbiotic | organisms are free-living and relationships are not required for survival |
| Synergism | Members cooperate and share nutrients |
| Antagonism | some members are inhibited or destroyed by others |
| What is phage therapy? | using bacteriophage as treatment of bacterial infections |
| What are the advantages? | antibiotics are not selective and there are side effects; bacteriophage are host cell specific and targets only cells causing infection |
| What are the disadvantages? | harder to culture in the lab, not sure whether its sterile or not, not sure if its the correct bacteriophage for the given infection |
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