Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Lab Test 03
| Question | Answer |
|---|---|
| What is an antigen? | Anything which causes an immune response, including the production of antibodies. A specific antigen will react with the specific antibody produced in response to it. |
| What is an antibody? | Y-shaped protein made by an immune system in response to an antigen. Can only attach to the antigen that caused it's production. |
| Bacterial flagella are composed of ___ antigens; cell surface antigens are called ___. | H ; O |
| Agglutination results from a reaction between: | An appropriate non-soluble antigen and an antibody. |
| The letters of the ELISA test stand for: | E= Enzyme L= Linked I= Immuno S= Sorbant A= Assay |
| What are some steps in identifying a bacterium? | Isolate the unknown into pure culture. Determine Gram reaction Determine cell morphology -- rods, cocci or other? Once you have the above, you can determine what other biochemical tests to run. |
| Explain how biochemical tests are, indirectly, testing a microbe's genetic makeup? | The biochemical tests are testing for the presence of certain enzymes - the presence of these enzymes is determined by the genetic makeup of the unknown bacterium. So the test result will reflect the bacterium's genetic make up. |
| What types of substances are placed into many of the biochemical media to detect whether or not the test bacterium is causing the expected biochemical reaction? | pH indicators |
| How do the sizes of Staphylococus colonies compare to the sizes of Streptococcus/Enterococcus colonies? | Staphylococcus colonies are medium to large in size, whereas Streptococcus/Enterococcus colonies are tiny, pin-point colonies. |
| What is the difference between the catalase test and the coagulase test? | Catalase test uses hydrogen peroxide& tests for the presence of the enzyme catalase (which breaks down the hydrogen peroxide into h20& o2). Coagulase test uses rabbit plasma and tests for the presence of the enzyme coagulase, which causes plasma to jell. |
| What characteristics are being tested for when inoculating bacteria on mannitol salt? | Ability of the bacterium to grow in the presence of 7.5% salt. Ability of bacterium, if it grows in salt, to ferment mannitol with the production of acid. |
| Some of the most serious nosocomial wound infections are caused by vancomycin-resistant Enterococcus species. How might these Enterococcus cells enter a wound? | The only way these species can enter a wound is if carried there by bad hygiene - on part of the patient or on the part of a health care worker. Someone is not washing their hands! |
| What is the significance of identifying a methicillin-resistant Staphylococcus aureus (MRSA) as the cause of a patient's infection? How might this type of infection be treated? | MRSA is more difficult to treat. Infecs must be treated w/powerful antibiotics. As this necessary treatment continues, we will select strains of S. aureus that are more resistant to antibiotics. There may come a time when it will not be possible to treat. |
| If you were to prepare a culture using a sample from a child's very red sore throat, what medium would you use and what results would you look for? | You are looking for the cause of strep throat, Streptococcus pyogenes. Use blood agar, streak for isolation and look for tiny, pinpoint colonies with b-hemolysis. |
| What is the catalase test? | It tests for the presence of catalase. It catalase is present, it causes the hydrogen peroxide to be broken down to water and oxygen -- bubbles. |
| Which biochemical tests require 24-hr incubation? | O/F Medium (glucose, sucrose, lactose) TSI Slant Citrate Urea Lysine decarboxylase |
| Which biochemical tests require 48-hr incubation? | MR (methyl red) VP (Voges-Proskauer) Nitrate reduction Motility |
| If an O/F sucrose medium is inoculated with a bacterial species and is yellow in both the top and bottom after 24hr, is it possible this species could produce the same result in an O/F glucose medium? | Yes. If the bacterial species can ferment other sugars, it can always ferment glucose. |
| If a species produces green top & green bottom after 24hrs in O/F glucose medium, is that bacterial species capable of respiration or fermentation or both? | Respiration (assuming the bacteria grew and there is cloudiness in the medium) Yellow reactions in O/F media indicate fermentation. |
| What is the indole test and what does it tell us? | The indole test tests whether a microbe can degrade the amino acid, tryptophan. Indole positive bacteria break down the tryptophan in the broth to produce indole. Bacteria incapable of performing this reaction do not produce indole. |
| What does the methyl red test tell us about the bacterium being tested? What color does the medium have when the bacterium is methyl red positive? | Methyl red tests tell us whether the bacterium is fermenting by a specific pathway(the mixed acid way). After addition of the methyl red reagent, the medium is red if the bacterium is MR+ |
| What does the VP test tell us about the bacterium being tested? | The VP test tells us whether the bacterium is able to ferment by a particular pathway(the butanediol pathway). |
| What causes the blackness in the butt of the TSI medium with some bacteria? | The blackness is caused by the production of H2S by the bacterium. The H2s reacts with the iron salts in the medium, producing the black colored ferrous sulfide. |
| If a bacterium causes the butt of a TSI tube to turn black, is it capable of fermenting glucose? | Yes. All bacteria capable of producing H2s can ferment glucose. |
| When a Simmon's Citrate agar slant turns blue, what is indicated? | The bacterium can use citrate (which is the sole carbon source in the medium.) |
| A bacterium is inoculated into some broth medium. After incubation, the reagents are added, and the medium turns red. Is the bacterium positive or negative for nitrate reduction? | Positive. The nitrate was reduced by the bacterium to nitrite. |
| A bacterium is inoculated into some nitrate broth medium. After incubation, the reagents are added, and the medium does not change. Zinc is added, and the medium turns red. Is the bacterium positive or negative for nitrate reduction? | Negative. None of the nitrate was reduced by the bacterium. |
| What are the IMViC tests, and why are they important? | The IMViC tests are: indole, methyl red, VP, and citrate. They are used to distinguish certain Gram negative rods with similar traits, especially those in the coliform group. |
| Name all the contents in the soft agar overlay at the moment it is poured into the petri dish? | Soft agar, phage, E. coli cells |
| What is a plaque? | A clear spot in a bacterial lawn where host bacterial cells have been killed (lysed) by bacteriophage. Each plaque represents thousands of killed host cells. |
| What is phage titer? | The number of bacteriophage per ml in a solution. |
| What would happen if you prepared the soft agar overlay with phage, but forgot to include the E. coli host cells? | No plaques would be present at all. Viruses cannot reproduce without host cells. |
| Plates 4 and 7 were prepared from the same 10^-4 dilution, yet they look different. Why is there a difference? | The plate w/Ecoli B host had plaques. The plate w/ reg. E coli host had no plaques. Reg did no have proper receptors for this bacteriphage to attach, so the virus is unable to establish an infec& kill host cells. Ecoli B=proper recept. for bacteriophage |
| We assume each plaque arose from _____ (how many) virus particles? | We assume that each plaque is a result of progeny from one virus: that a single virus landed in that spot & infected a host cell, and that virus' progeny infected that surrounding host cell. |
| What purpose is served by the regular agar layer in the lower portion of each petri dish and what purpose is served by the use of the soft agar upper layer in each petri dish in this experiment? | The regular agar layer provided nutrients to the host cells. The soft agar layer allowed for the virus to move readily to other host cells. |
| Can bacteriophage used in this lab effect human cells? | No. Human cells do not have the right kinds of receptors. |
| How can a Salmonella bacteriophage be used to identify whether/not an unknown bacterium is Salmonella. | Prepare soft agar overlay using unknown bact. mixed w/salmonella bacteriophage. If plaques form= then unknown is salmonella. If no plaques= other species or strain of Salmonella. |
| Suppose you mixed a newly isolated bacteriophage w/ the appropriate host cells & prepared a soft agar overlay. After incubation, you see no plaques in any of the plates. Why might this be? | The virus may be temperate which undergoes the lysogenic cycle. As long as such a virus is still in the lysogenic cycle, no host cells will be lysed, and no plaques will be soon. |
| In the ELISA test, if you wish to test for the presence of a specific antigen in a patient stool sample, what would you use to capture that antigen from a sample containing many different antigens? | The specific antibody that could bind to that antigen. |
| In the ELISA test, if you wish to test for the presence of a specific antibody in a patient sample, what would you use to capture that antibody from a sample containing many different antibodies? | The specific antigen that could bind to that antibody. |
| What type of patient sample would you use to look for this antibody? | Blood serum since this is where antibodies are found; of course, since blood moves throughout the entire body, the antibodies can also move from blood to tissues by diffusion. |
| In the ELISA test, what is used to actually visualize whether or not the target antigen or antibody has been captured? | An enzyme-linked antibody (made of an antibody that can attach to the target antigen or antibody) AND a colorless substrate that can react with the enzyme to produce a colored product. |
| What is epidemiology? | The study of disease frequency and distribution in a population. |
| Why are positive controls included in ELISA test? | This is used to make sure the reagents are functioning properly-- to make sure these systems will react properly. To make sure positive samples react positively. |
| Why are negative controls included in ELISA test? | This is used to be sure that in the absence of the test antigen we do not still get a positive reaction. If a negative control gives a positive result, reagents may be contaminated. |
| What do the results of the slide agglutination test indicate? | It indicates the specificity of antibodies-- they will only react w/the proper antigens. In this case, Salmonella O antibodies will only react with Salmonella O antigens, and will not react w/ the Salmonella H antigens. |
| What is the significance of the letter/number designation of E.coli 0 157:H 7 ? | The 0 157 indicates a specific cell surface protein; the H 7 indicates a specific flagellar protein. The numbers are identifying numbers assigned to each particular antigen. |
| Why are ELISA tests so popular in clinical labs? | They are very accurate and very fast. |
| In a slide agglutination test that shows agglutination, what molecules compose the granular, agglutinated mass? | These are the result of antibodies linking to antigens; the granules are antibody-antigen complexes. |
| How could increased antibody levels and increased white blood cell levels be related? | The increase cell division of lymphocytes are B- cells which (once they have detected antigens and have been activated) would become plasma cells and make antibodies. |
Created by:
ilymucho
Popular Biology sets