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27 Cards in this Set
- Front
- Back
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What is Tranformation is the ability of...
... the information encoded in the genes of that DNA |
..bacteria to take up DNA fragments from the environment and ultimately express ...
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Why does transformation has implications for antimicrobial chemotherapy?
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Because the genes that are taken up by transformation may be genes that code for antibiotic resistance.
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What is Heat shock
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both tubes by submerging the bottom 1/2 of the tube into the 42C waterbath and agitating bouth of the tubes by gently shaking them back and forth for 90 seconds
(Heat shocking allows the DNA to more readily enter the cell) |
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In this exercise we will transform a strain of E.Coli that is normally susceptible to..
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ampicillin into a resistance stain
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Bacteriophage or simply phage is...
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a virus which infects bacteria. Viruses are obligate intracellular prarsite. They can not synthesize proteins or generate ATP and consequently can only replicate insede a living host cell.
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what is the lytic cycle?
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a phage attaches to the host cell by means of tail fibers that recognize specific receptors on the surface of E.coli
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Which enzyme does the phage releases?
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lysozyme, which dissolves part of the bacterial cell wall.
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What does the phage tail do?
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the phage's tail sheath then contracts and drives the phage core, a hollow tube, through the cell wall injecting its DNA into the host cell.
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what is DNA and systhesizes happens in a phage?
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the phage "high jacks" the machinery of the host cell and the host cell begins to replicate the phage DNA and systhesizes the phage structural components. The phage components are assembled and packaged with the phage DNA and the host cell disitegrates releasin new phage that in turn can infect other host cells.
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VIRONS
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T4 this process from attachment of the phage to lyses of the host cell takes about 25 minutes and releases as many as 100-200 new virions.
Viron: is a complete assembled virus capable of infecting a cell |
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PLAQUES- while this viruses can only be seen with an electron microscope, their effect on an agar, surface coasted with E.coli...
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can be seen clearly as holes in the lawn of bacteria called Plaques.
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EPIDIMIOLOGY
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STUDY OF DISEASE
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Infectious Disease
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disease in which pathogens invade a susceptible host and carry out at least part of their life cycle in the host.
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Communicable disease-
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disease that spreads from one host to another
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Epidemic disease
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disease in a given area over a short period of time
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Pandemic disease
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-disease aquired by many people around the world in a short period of time.
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Universal Precautions
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guidelines to protect workers from exposer to disease by blood and certain bodily fluids.
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Describe three means of disease transmission:
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shaking hands, blood and bodily fluids
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What infectious diseases can be tranmitted in fecally contaminated drinking water?
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cholera, amoebic dysentery,giardiasis, traveler's diarrhea, Hepatitis A, and criptosporidiosis
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To assure that our drinking water is POTABLE (safe to drink) our drinking water is...
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constantly monitored for both toxic chemicals and microbial contamination.
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It is not practical to look for specific pathogens in our water supply, instead water is...
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...screened for Indicator Organish or Sewage Indicators. sewage indicators are consistently present inhabitants of the intestinal tract and their presence in water is a good indication that fecal material has entered the water supply.
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There are two types of sewage indicators that are currently tested for:
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Streptococcus faecalis (now referred to as Enterococcus faecalis) and coliform bacteria
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Coliform Bacteria, by definition, are gran negative.....
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non-spore-forming, facultative anaerobic rods that ferment lactose producin acid and gas.
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MPN Most probable number...
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Miltiple-tube technique is use to determine the most problable number (MPN) for coliform bacteria per 100 ml of a water sample.
This particular method involves three different test: the presumptive, the confirmed and the completed. |
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Presumptive test...
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a set of lactose broth tubes containin Durham tubes is inoculated with the water sample. The presence of a gas bubbles in the Durham tube indicates a positive reaction. A presumptive MPN is then determined by comparing the number of positive tubes to a standard table called the MPN index.
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Confirmed test:
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EMB plates are inoculated with samples from any positive lactose broth tubes from the presumptive test. This media inhibits the growth of Gram-positive bacteria while Gram-neg bacteria that ferment lactose will grow with distinctive dark purple colonies or produce a metalic green sheen on the agar surface.
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Completed test
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a nutrien agar slant and a lactose broth tube are inoculated with colonies from the EMB plates that are consistent with gram-neg lactose while fermenting bact. A gram stain is made from the nutrient agar slant to determine if the colonies on the EMB plate are in fact Gram-negative rods. The lactose broth tube contains the pH indicator phenol red and a Durham tube and if the bacteria are indeed coliforms the tube will turn yellow and Durham tube will have a gas bubble in it.
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