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56 Cards in this Set
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Describe bacterial communities, including several properties of biofilm. |
biofilm formation begins when planktonic prokayotic cells move to a surface and adhere, where the y mulitiply and release polysaccharides, DNA, and other hydrophilic polymers to which unrelated cells may grow. The meshlike accumulation of these polymers (EPS's) gives biolfilm the slimy appearance. Forms plaque on teeth- hard to treat because because microbes with the protective EPS often resist effects of antibiotics. They can be beneficial. Many biorememdiation efforts are enhanced by biolfilms. Bacterial communities: Can help each other out or leech off each other. For example, Organisms that cannot multiply in the presence of O2 will grow in the mouth if neighboring microbial cells consume that gas; one species creates an environment in which the other can thrive. Metabolic waste of one organism can be nutrients for other. Microbes can compete: microbes can synthesize toxic compounds that can inhibit competitors. |
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Give several reasons why an understanding of prokaryotic cell structures and their functions is important. |
They are different from eukaryotes use surface parts to communicate and for identification can be targeted with drugs if we understand the composition of the cell wall. They can cause consequences, like food borne pathogens. |
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What is the main function of the cytoplasmic membrane for bacteria. Describe organizations and functions of the lipid and protein components of the cytoplasmic membrane. |
It serves as a critical permeability barrier between the cell and its external environment. The proteins have several functions. Some act as selective gates, allowing nutrients to enter the cell and wasted products to exit. Others serve as sensors of environmental conditions, providing the cell with a mechanism to monitor and adjust to its settings. |
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Osmosis |
Osmosis is when water moves down the concentration gradient from high water concentration to low concentration. The environment in which prokaryotes is very dilute (hypotonic) |
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Explain the following modes of transport across the cytoplasmic membrane: simple diffusion, facilitated diffusion, and active transport. |
Molecules that can move in and out of the lipid bilayer use simple diffusion. Molecules move from a region of high concentration to one of low concentration, until equilibrium is reached. Facilitated diffusion is a form of passive transport, so it does not require energy. It uses a transport protein to move substances from one side of the membrane to the other, but it can only eliminate a difference in concentration, not create one. Molecules are transported until there is an equilibrium reached on both sides. Active Transport moves compounds against the concentration gradient and requires energy. Use ions or ATP |
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What is the main function of the cell wall for the bacteria? Describe the composition of peptidoglycan. |
The cell wall is a structure that prevents a cell from bursting. Peptidoglycan- A material found only in bacteria N-acetylmuramic and N-acetylglucosamine: NAM and NAG form the structure of the peptidoglycan. The sub units are related to glucose, and are joined to form a glycan chain. They serve as a backbone to the peptidoglycan molecule. Tetrapeptide: Attached to the NAM molecule is a tetrapeptide chain (string of 4 amino acids) Forms a fence of tetrapeptide chains. In gram negative, joined directly In gram positive, interbridge (chain of amino acids) |
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Describe composition and function of Gram positive cell walls. List functions of the cell wall proteins |
Thick layer of peptidoglycan Peptidoglycan is permeable to sugars, amino acids, etc. Teichoic acids: Important for cell wall construction and cell division. Bind to cations (may serve as resevoir for cations) |
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.Composition and function of Gram negative cell wall. What aspect will make these bacteria relatively resisitant to lysozome, bile salts and some antibiotics? |
Thin layer of peptidoglycan. It is resisitant to the things because of its outer layer. This is because it is made up of a molecule called lipopolysaccharide (LPS) this can be deadly when injected into a human, and the human's response will actually be symptoms of infection. |
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Explain how the effects of being placed in a low solute solution would differ between penicillin treated Gram positive vs. Gram negative cells. |
Penicillin prevents peptidoglycan synthesis, weakening cell walls and inhibiting growth of gram positive bacteria. This makes them likely to burst in hypotonic surroundings. Gram negative are less likely to die because penicillin doesn't prevent their cell wall synthesis. |
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What are porins and how do they function in the outer membrane of gram negative bacteria? |
Porins are specialized channel forming proteins that span the outer membrane. Small ions and molecules can pass through the membrane. Some porins are specific for certain molecules, others allow many different molecules to pass. |
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Define and describe the lipopolysaccharide layer (LPS) as well as lipid A and O antigen in LPS. |
LPS is crucial in identifying if a gram negative bacteria has entered the blood stream through a wound. When it enters the bloodstream, it will cause symptoms characteristic of infection. If there were only small amounts, it could be treated. If there were large amounts, then it could be deadly, which is why LPS is called an endotoxin. (ASK AND SEE IF YOU ARE CORRECT) Lipid A- anchors the LPS molecule in the lipid bilayer. This is the portion of the LPS molecule that the body recognizes as the sign of invading Gram negative bacteria. O antigen- the portion of LPS directed away from the membrane, opposite from Lipid A. It is made up of a chain of sugar molecules, which is different among many species- these help identify certain species or strains. |
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What is Endotoxin? How can it be released and cause symptoms in a human host? |
It is the lipid A portion of LPS When cells are dying, they release outer membrane components, so endotoxins can be released. Endotoxins can over ride selectivity of immune system, makes it react |
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Describe the types of cell walls in the following bacteria: Mycobacteria, archaea, and Mycoplasma. |
Mycobacteria: thick peptidoglycan wall in wall is waxes that are part of wall. Mycoplasma: Variable shape because they lack a rigid cell wall. Neither penicillin nor lysozome affects these organism. Can survive without a cell wall because cytoplasmic membrane has sterols in it, making it stronger than most other bacteria. Archaea: Have a variety of cell walls. No peptidoglycan in the cell walls. |
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Describe the structure and composition of bacterial capsules and slime layers. How variable are these structures among different species and strains of bacteria? |
Capsule: Distinct and gelatinous Some allow bacteria to avoid host defense systems that otherwise protect against infection. Slime Layer: Diffuse and irregular Both: Most composed of polysaccharides Commonly refered to as glycocalyx Allow bacterial cells to adhere to specific surfaces. Once attached, cells can grow as biofilm. |
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Describe the structure, arrangements and movement of bacterial flagella. Describe the main function of flagella for bacteria, including definition of chemotaxis. |
Three basic parts: A filament, a hook and a basal body. Filament: extends into external environment. Subunits of protein called flagellen. Forms a helical structure with hollow core Hook: Connects filament to cell surface Basal Body Anchors the structure to the cell wall and cytoplasmic membrane Main function: Act as propellars that push the cell through liquid. Chemotaxis: Most bacteria sense the presence of of chemicals, will then move in a certain direction. |
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Describe the structure of bacterial pili. Explain the function of fimbriae and how fimbriae help bacteria to colonize a host's body. Function of pili. |
Structure is to flagella, string of protein subunits with hollow core. Pili are shorter than flagella. Many types allow cells to attach to certain surfaces, these are called fimbriae. Without ability to attach, they could just run through the intestinal tract (E. coli for example) Some types help bacterial cells move on solid surfaces |
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.Explain the function of sex pili, including the process of of bacterial conjugation between an F plus and an F minus bacteria |
Sex pili is used to join one bacterium to another for a specific type of DNA transfer. F plus and F minus are types of horizontal gene transfer. F+ plasmid enables to make sex pili. Receptor then copies F+ plasmid to the F- F- becomes F+ because it got a copy of the plasmid |
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Describe structure and composition of a typical prokaryotic chromosome. |
Chromosome- contains DNA Plasmids- double stranded DNA molecules. Smaller than chromosome. Ribosomes- involved in protein synthesis. Cytoskeleton-interior protein framework. Storage Granules- Stores molecules that are not used rather than it be wasted and stored to be used later. Gas Vesicles- provide buoyancy to the cell for aquatic bacteria Endospores- dormant cell |
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.Explain how genetic diversity contributes to evolution by natural selection. Give several reasons why prokaryotes can evolve so quickly. |
As a consequence of bacterial genetic diversity, there are likely to be some bacteria that can survive a change in their surroundings. Survival and growth of certain variants in a particular environment is the natural selection force of evolution. Prokaryotes can reproduce quickly, go undergo frequent genetic changes and can evolve quickly. |
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Describe the structure and properties of plasmids. Explain how antibiotic can be conferred by genes on plasmids. |
Plasmids are circular, supercoiled, double stranded DNA molecules. A single cell can have more than one type of plasmid. Many plasmids code for production of enzymes that destroy certain antibiotics, allowing the organism to resist them. Sometimes bacterium can transfer a copy of the plasmid to another cell, so this information can spread. |
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.Describe the structure of prokaryotic ribosomes and explain their function. |
Prokaryotic ribosomes are 70S, Eukaryotic are 80S. They are involved in protein synthesis, and they facilitate the joining of amino acids. |
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Describe the prokaryotic cytoskeleton |
It was once thought that bacteria lacked a cytoskeleton. Appear to be involved in cell division and controlling cell shape. |
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List some of the substances in bacterial storage granules. |
Store nutrients that a cell has excess of. It can store carbon, and produce glycogen |
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Sporulation |
Has to do with endospores. It is endospore formation. It is a complex sequence of changes that begin when spore forming bacteria experience limited amounts of nitrogen or carbon. |
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Process of germination. What are vegetative cells? |
Germination can be triggered by exposure to heat or certain chemicals. The endospore then takes on water and swells. The spore coat can then crack open, and a vegetative cell grows out. Vegetative cells are the multiplying cell. |
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Describe the structure and function of the eukaryotic plasma membrane. List some functions of the plasma membrane proteins. |
It is a typical phospholipid bilayer embedded with proteins. It is a permeability barrier, does trasnport and cell to cell communication. Some proteins are involved in transport, others are attached to internal structures helping to maintain cell integrity. Those that face the outside often serve as receptors. A receptor can bind to a specific molecule (a ligland) These allow cells to communicate with each other. |
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Explain how a macrophage destroys bacteria by phagocytosis. How does a macrophage "recognize" a bacteria, and roles of the phagosome and lysosomes. |
Type of phagosytic cell has receptors that bind to bacteria. Once bacteria gets bound, cell gets brought into phagosome Phagosome contains cell |
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Describe the following eukaryotic cell structures and functions: ribosomes, cytoskeleton, flagella and cilia, nucleus, chromosomes, mitochondria, and chloroplasts. |
Ribosomes Involved in protein synthesis. Cytoskeleton Forms a framework of three componenets: Actin filaments, allow cell to move microtubules, help cells reproduce Intermediate filaments, allow cells to resist physical stress Flagella and cilia Allow cell to move by using ATP Nucleus Contains the genetic information Mitochondria Function as ATP powerhouses Chloroplasts Found in plants and algae Site of photosynthesis |
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Explain the endosymbiotic theory of the evolutionary orgin of mitochondria and chloroplasts. |
The theory states that the ancestors of mitochondria and chloroplasts were bacteria residing in other cells in a mutually beneficial partnership. (an endosymbiont) As time went on, each partner became necessary to the other, and the endosymbiont eventually lost key features such as a cell wall and ability to replicate independantly. |
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Explain the process of binary fission. |
It is a process where a cell increases in size and then divides. Once cell divides into two, then 4, 8 and so on. The time it takes for a population to double in number is generation time. Generation time will vary between species. |
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Be able to answer growth rate problems: If the generation time of a bacteria is 20 mins, how long will it take for 6*10^3 cells to become 4.8*10^4 cells? |
Nt=No*2^n Nt=number of cells in population at time t No=original number of cells in population N=number of divisions |
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Identify and explain what is occurring during each of the stages of the growth curve. |
Lag phase: no increase in cell number; cells begin synthesizing enzymes for required growth. Lag phase will be longer depending on environment (fewer nutrients, lag phase is longer) Exponential or log phase: cells divide at constant rate. Generation time is measured during this phase. Bacteria are most sensitive to antimicrobial medications when cells are actively multiplying. Stationary phase: nutrient levels are too low to sustain growth. The total number of viable cells in the population remains relatively constant, but some are dying while others are multiplying. Death phase: the period when the total number of viable cells in the population decreases as cells die off at constant rate. Phase of prolonged decline: Usually, a fraction of the cells have survived death phase. They can multiply for a short time using the dead cell's nutrients. Most of the survivors then die. The ones that do survive become slightly modified and are better equipped for survival. |
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What are the temperature conditions for the following types of organisms |
Psychrophiles: optimum between -5*C and 15*C Psychrotrophs: optimum between 15*C and 30*C but grow better at lower Mesophiles: optimum between 25*C and 45*C. E coli are in this group, pathogens. Thermophiles: optimum between 45* and 70*C. Hot springs Hyperthermophiles: optimum 70*C or greater. Usually archaea. |
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For each of the following classes of microbes, what are the O2 conditions for growth and the metabolic process for obtaining energy to make ATP? |
Obligate aerobes- absolute requirement for oxygen. Use aerobic respiration M.luteus Obligate anaerobes- Cannot multiply if O2 is present, can be killed. Do not use aerobic respiration. C.botulinum Facultative Anaerobes Grow better is O2 is present, but can grow without Can use aerobic respiration, but also others if it is not present. E.coli Microaerophiles Require small amounts of O2 Use aerobic respiration H.pylori Aerotolerant anaerobes Are indifferent to O2 Can grow in presence, but do not use it to harvest energy. They use fermentation for energy. S.pyogenes |
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What are the two main toxic deriatives of oxygen produced in cells? Name and explain the activities of the two enzymes that destroy them. |
Superoxide and catalase |
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For each of the microbe classes in question 7, describe a) where the microorganisms grows in a shake tube and b) which enzymes the microorganism produces to neutralize the toxic derivatives of oxygen. |
Obligate aerobe: Grow at top of tube. Produces superoxide dismutase and catalase Facultative anaerobe: More concentrated at top, but found all over. Produces superoxide dismutase and catalase Obligate Anaerobe: Microorganisms found at bottom of tube Does not use SD or C, what does it use???? Microaerophile: Grows towards the top Produces some SD and C Aerotolerant anaerobe: Grows equally throughout the tube Produces SD, but not C |
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What are the pH conditions for growth of most bacteria? What are acidophiles and alkaliphiles? |
Most microbes are neutrophiles, and they they live and multiply within a range of pH 5 to pH 8. Optimum pH is 7. Acidophiles grow optimally below 5.5 Alkaliphiles grow optimally above 8.5 |
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What is meant by water availability? Describe the growth conditions of halotolerant microbes, halophiles, and extreme halophiles. |
All microorganisms require water for growth. Even if water is present, it may not be available in certain environments. NaCl and sugar will interact with water molecules, making them unavailable. If solute concentration is higher than water, water diffuses out of cell due to osmosis. The cytoplasm with shrink and dehhydrate, this is called plasmolysis. Halotolerant: microbes that can tolerate high concentrations of salt, up to 10% NaCl. Staphylococcus is an example of these. Halophiles: require high levels of NaCl. Many marine bacteria are mildly halophilic. Extreme Halophiles: require 9% NaCl or more. Found in Dead Sea. |
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List several of the most important major elements needed for bacterial growth. Why are these elements necessary?
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Carbon, hydrogen, nitrogen, sulfur, phosphorus, potassium, magnesium, calcium and iron. Nitrogen is needed to make amino acids. Heterotrophs use organic carbon, which plays a critical role in cylcing carbon in the environment, essential for life. Phosphorus and iron are important because they are available at lowest concentration relative to need. Other elements are required for some enzyme functions. |
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What do heterotrophs use for their carbon source? What do autotrophs use? |
Heterotrophs use organic carbon Autotrophs use inorganic carbon. |
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What do chemotrophs use for their source of energy (to make ATP)? What do phototrophs use? |
Chemotrophs use energy from chemical compounds. Phototrophs obtain energy from sunlight |
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Explain the energy and carbon sources of the following groups of prokaryotes: photoautotrophs, photoheterotrophs, chemolithoautotrophs, and chemoorganoheterotrophs. |
Photoautotrophs: use energy of sunlight to make organic compounds from CO2 in the atmosphere. Photoheterotrophs: use energy of sunlight and obtain carbon from organic compounds. Chemolithoautotrophs: use inorganic compounds for energy and obtain carbon from CO2 Chemoorganoheterotrophs: use organic compounds for energy and carbon |
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.Define each type of media, and give reasons for its use: complex, chemically defined, selective, and differential. Give at least one example of each type of media. |
Complex Media: contains a variety of ingredients such as meat juices and digestive proteins. Specific amounts are in medium, but composition can highly vary Examples: Blood agar (contains red blood cells) chocolate agar (contains lysed red blood cells) Chemically defined media: composed of exact amounts of pure chemicals.Used for specific experiments where elements must be highly controlled. Can support growth of E. coli. Examples: ? Selective Media: inhibit growth of certain species in a mixed sample, while allowing growth of other species. Example: Thayer-Martin agar (can isolate Neisseria Gonorrhoeae), MacConkey agar (can isolate gram negative rods) Differential media: contains substances that certain microbes change in a recognizable way. Example: Blood agar |
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Describe how obligate anaerobes can be grown in the lab. |
Those that can tolerate brief exposures are incubated in a anaerobe container. More stringent way is to use an anaerobic chamber, which is an enclosed compartment maintained as an anaerobic environment. A special port that can be filled with inert gas is used to add or remove items. |
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Explain the purpose and procedure of an enrichment culture. |
It is used to isolate an organism present as only a very small fraction of a mixed population. It does this by providing conditions that will preferentially enhance the growth of a particular species in a broth. A sample is added to a broth medium designed to favor the growth of a desired organism over others. |
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Describe the contributions Robert Hooke and Leeuwenhoek made to Microbiology |
Hooke coined the term "cells" Leeuwenhoek scraped lenses together and created the first microscope with 200x magnification. He was also the first to see bacteria |
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Explain the theory of spontaneous generation and how Louis Pasteur disproved this theory |
The theory was that microogranisms could just start growing without any sort of stimulation or source to grow on/in Pasteur proved this was not true by doing the goose neck flask experiment. He filled the body of the flask with sterile broth, and air could escape from the open end of the flask. Years passed, and the broth stayed sterile while there was bacteria in the neck. Once the bottle was tipped to the side and came in contact with microorganisms from the air, the broth became infected and the bacteria multiplied. |
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Describe some of the special and fascinating properties of microorganisms, with respect to each of the following: size, diversity, abundance, genetics and reproduction, evolutionary origin, and vital activities |
Size: MO's can be anywhere to 1-10 micro meters in size. Bacteria are the smallest cells (prokaryotic) Bacteria are te smallest living organism that can produce on its own. (unicellular) Abundance and diversity: Humans: 10,000 more bacterial cells on humans than human cells in/on the skin Over 100 trillion bacteria, 10,000 species Different types of bacteria in different locations, different types in different individuals. 1,000 different types per person. Most concentrated in the large intestine. Then the mouth, nose, throat, skin, urogenital area. Environmental: Soil has a lot- 5,000 different species. Reproduction and Genetics: Bacteria can reproduce as fast as every 20 minutes. (binary fission) Is this same for eukaryotes and archaea? Human cell division takes about 24 hours. Genetic material has to replicate before cell divides. Genes: sequence of bases (A,G,C,T) codes for a protein. Genome refers to all DNA of humans 3 million bacterial genes contributed by the human microbiome (150x more genes than human genes) Bacterial Genetic change: Horizontal gene transfer- bacteria requires new DNA from another possibly dead bacteria Mutation- spontaneous during DNA replication Evolutionary origin Ancestors live 3.5 billion years ago. Vital Activities: Environmental: Decompose organic material Convert N2 into usable organic compounds Produce O2 by photosynthesis Importance for Human Health: Digestion of materials Development and normal function of immune system Prevent pathogens from colonizing in body |
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Give a few reasons why it is important to study the human microbiome. |
It is important for maintaining human health. If we are not aware of the different types of infectious agents and how to deal with them, then the human race would not survive. |
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.Give some more examples how microbiology research can benefit humans and the environment. |
Scientists help to diagnose diseases such as meningitis and tuberculosis, and help to prevent the spread of diseases by identifying, containing, and treating disease in the human body. The work of medical microbiologists is constantly evolving as new bacteria and infections are identified and categorized. It is important that we keep up with finding new strains of certain viruses and pathogens and how to prevent them from spreading. Environmental microbiologists may also study the ways in which certain microorganisms can work as effective agents to degrade various types of human and industrial waste products. We would be living in waste if we did not study how we can break down materials and live in a clean environment. |
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List several infectious diseases that have had an impact on humans throughout history. |
Tuberculosis E bola H1N1 Measles Plague Polio Spanish Influenza Lyme C.Diff |
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Define emerging and re-emerging disease and give examples of them |
Emerging- new infectious agents that infect humans, a new virus or bacteria that has come about. Examples: HIV/AIDS H1N1 Lyme C.diff SARS MERS E bola Re-emerging- Not new, a microbe that was able to create a new strain Examples: Whooping cough Measles Meningococcal Polio |
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Summarize at least five factors that can contribute to increasing rates of emerging and re-emerging diseases. |
Agent Factors- Microbe changes to infect humans Able to escape human response Resistance to antibiotic (develops new protein) Host factors- Decrease in vaccinated people Increase in immunocompromised people Environmental factors- Lack of sanitization Change in climate Social Upheaval |
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Explain how antibiotic resistant strains of bacteria can develop. |
When a bacterial population is exposed to an antibiotic, any bacteria that are resistant to it can survive and continue to grow, while abx sensitive bacteria are inhibited or killed. The surviving bacteria can reproduce and their descendants spread to environment and other hosts. |
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What are the three Domains of Life? Is each prokaryotic or eukaryotic and what are the main differences between these cell types? |
Bacteria Prokaryotes, no enclosed nucleus, unicellular Archaea Prokaryotes, found in extreme environments (high salt, high sulfur) Eucarya Eukaryotes Algae: uni or multicellular, Protozoa: unicellular (protists) Fungi: uni or multicellular, Helminths: multicellular parasites |
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Describe the major characteristics of each of the following types of microorganisms: Bacteria, Archaea, Protozoa, Fungi, Algae, and Viruses |
Bacteria: No enclosed nucleus Prokaryotic (unicellular) Archaea: Found in extreme environments- High salt, high sulfur Protozoa: "Ingest" organic substances Unicellular Fungi: Use organic compounds for energy They are mold, yeast, which can cause infection Algae: Environmental, photosynthesize Convert CO2 into sugar Produce oxygen Can be multicellular Viruses They have own genes THey are not cells, they are acellular which means they are made up of infectious particles. Genetic material with protein coat Have to get into host to infect. Can only multiply in a living host cell. |
