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Micro Lab Final

NWHSU Micro Lab

QuestionAnswer
Define titer The highest dilution of a sample that tests positive for an antibody.
Which immunoglobulin appears first when someone has an infection? IgM
Define Prozone. During antibody precipitation tests, its the period of time when antibody concentrations are high and no precipitates are formed, leading to false negatives.
How is a positive Western blot for HIV determined? There will be two or more dark bands.
what are the reagents in gram staining? Crystal violet, Grams iodine, acetone-alcohol, safranin.
In gram staining, what does crystal violet do? stains all gram + and - bacteria.
In gram staining, what does grams iodine do? its a mordant that forms violet-iodine complex that binds more.
In gram staining, what does acetone-alcohol do? It decolorizes gram - bacteria. But only if not done for too long.
In gram staining, what does safranin do? counterstains gram - bacteria.
What color are gram positive bacteria? Purple
What color are gram negative bacteria? pink
How do gram stains and wet mounts vary? Gram can determine gram +/-. Wet mounts can tell motility.
How are gram stains and wet mounts similar? They both can see arrangement, size, and shape.
What is the KOH test to differentiate gram positive from gram negative bacteria? Mix KOH with a colony for 20 seconds. Stringy=negative. Not stringy=positive.
Define ubiquity Microorganisms everywhere.
What are 3 spore forming bacteria that cause disease? Bacillus Anthracis, Clostridium tetani, Clostridium botulinum.
What bacteria causes anthrax? Bacillus Anthracis
WHat bacteria causes Lock jaw Clostridium tetani
What bacteria causes botulism Clostridium botulinum
Define alpha hemolysis and what does it look like? Bacteria that can partiatlly break down heme pigment (green halo)
Define beta hemolysis and what does it look like? bacteria that can break down heme pigment fully. (clear zone)
Define gamma hemolysis and what does it look like? bacteria that show no change to a blood agar plate.
Which hemolysis is a lab looking for in diagnosing strept throat? beta hemolysis
What is the importance of a capsule? It protects against microphages in lungs.
What stain shows a capsule? gin stain.
what is the name of the acid-fast stain and what is it used for? Ziehl-Neelson procedure uses carbol fushsin. It detects bacteria with cell walls rich in lipids and waxes. LIke Mycobacterium and Nocardia. Leprosy, TB,
Define selective media? Isolates/cultivates for specific bacteria
Define differential media? Shows chemical reactions of bacteria
Is MacConkeys selective or Differential? Selective
Is blood agar selective or differential? Differential
What is the catalase test for and what reagent does it use? H2O2. Catalase breaks H2O2 into H2O and O2. Differentiates streptococci (cat-) from staphlococci (cat+)
What is the coagulase test for? Coagulase enzyme that breaks fibrinogen to fibrin. Staph aureus (coag+). Other staphs (coag-)
How is carbohydrate differentiation determined? Phenol red is used to determine a pH change. Red=no change, Yellow= pH drops and fermentation of carbohydrate has happened. CO2 gas may also be produced
HOw does a positive hydrogen sulfide test appear? Dark precipitate forms with Iron when hydrogen sulfide is present.
How does a positive urease test appear? Pos=bright pink. Neg=salmon->yellow
How does positive citrate test appear? Pos=blue. Neg=green
Given a bacterial plate count from a urine culture be able to decide if there is a UTI. (#colonies)x (_mL urine)= colonies/mL. 1K-10K = probable contaminated sample. 10K-100K=possible UTI. >100K= UTI.
Which 3 bacteria does the FDA recommend for disinfectant testing? S.Aureus (gram +, infection of wounds), P.aeriginosa (gram -, often fatal), Solmonella typhi(gram -, hard to disinfect).
Given results from antibiotic testing be able to determine resistance of susceptibility to antibiotics Measure zone of inhibition and compare to reference chart to determine resistant, intermediate, or senstive(suceptable)
Where does teh yeast cryptococcus cause serious infection? Spinal fluid.
Define dimorphic fungi. They exist as yeasts and molds
Define budding in yeast. Yeast makes a small copy of itself that will grow into a new yeast cell.
How would a gram stain be used with fungi Fungi appear gram + but larger than bacteria
HOw would a KOH stain be used with fungi? KOH when mixed with tissue will digest tissue, but not fungus. A wet mount can be used to see hyphae.
How would an india ink stain be used with fungi? Cryptococcus which causes meningitis can have a clear capsule.
What is the scotch tape test for? Pinworm infections
What is the disease or condition called cysticercosis and what parasite causes it? When humans are intermediate hosts for the pork tapeworm.
Infective stage and how diagnosed for giardia.. ingest cysts. Stool sample for cysts or trophozoites
Infective stage and how diagnosed for Hookworm (necator americanus) Direct skin penetration. Stool for ova.
Infective stage and how diagnosed for Ascaris. Ingestion of ova. Stool for ova.
Infective stage and how diagnosed for beef/pork tapeworm (Taenia saginata or Solium) Ingest larva. Stool for ova and proglottids.
Infective stage and how diagnosed for Trichomonas Sexual transmission of trophozoite. Wet mount of genital secretions for trophozoite.
What the insect vector for Trypanosoma brucei? Tsetse fly
What the insect vector for Trypanosoma cruzi Reduviid bug
What the insect vector for Leismania Sandfly
What the insect vector for Plasmodia? Mosquito.
What two roundworms or nematodes have a larval stage migrating through the host lungs? Ascaris lumbricoides, Necator americanus.
What two parasites use direct skin penetration as the way to enter the host? Hookworms (necator americanus) and Blood fluke (Schistosoma).
What stage of plasmodia in the mosquito is the infective stage for humans? Sporozoite
What stage of the plasmodia in the human host is the infective stage for mosquitoes? Gamatocytes
What stage in the plasmodia life cycle is occuring when the human host experiences fevers and chills? Erythrocytic cycle when merozoites are released
In which host does the asexual reproductive life cycle of plasmodia take place? Human
In which host does the sexual reproductive life cycle of plasmodia take place? Mosquito
Where in the human host does Toxoplamsa gondii infect? CNS, heart and skel muscle.
In what host does teh sexual reproductive cycle of toxoplasma gondii occur? Cats
What parasite causes african sleeping sickness? Trypanosoma brucei
What parasite causes changas disease? Trypanosoma cruzi
How would an individual get a Trichinella infection? Ingestion of larva in skeletal muscle.
What have molecular techniques to identify pathogens replaced some of the traditional methods? They've become cheaper. They can identify bacteria that doesn't grow well on media.
What is 16S rDNA and how is it used to identify bacteria? A small subunit of ribosomal DNA. Species have unique 16S rDNA sequences.
What is PCR? It marks a region of DNA and replicates it.
What are the 3 steps in PCR? Separate the DNA strands, Annealing the primer to the template, synthesis of new DNA strands.
What are primers? Small pieces of DNA that bind to specific sequences. Signals DNA polymerase to copy the region.
What is meant by conserved and variable regions of DNA? Conserved=regions that are similar across species. Variable=regions are more species specific.
How is cycle sequencing different from PCR? In cycle sequencing, copies are made of target DNA but each copy terminates randomly with special nucleotides.
What is BLAST? A database for matching DNA sequences and ranks them based on level of similarity.
Created by: Tammy Danielson Tammy Danielson on 2014-04-07



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