Microbiology Lab Final
black color in more than 50% of the test tube
+ bile reaction
What is the composite reaction of "Tube E" in this SIM media test set?
+/+/+
A student wants to view cells under the compound microscope at a total magnification of 400X. If the eyepiece is 10X, which of the following objective lenses should be used?
40X
A bacteria that will grow well in the environment of a refrigerator at a temperature of ~4°C could be best classified as?
A psycrophile
An organism that grows best at a pH of 4 and also only grows in the top of the nutrient broth tube could best be described as?
Aerobic acidophile
A fundamental technique important in the laboratory and used by microbiologists for a variety of procedures such as, transferring cultures, inoculating media and isolation of pure cultures is known as?
Aseptic technique
Which of the following is TRUE of aseptic technique?
Aseptic technique is intended to minimize contamination from unwanted organisms.
Why are organic acids often used to preserve foods?
Because many bacteria do not have the ability to grow in acidic environments.
The process of fermentation includes the production of any or all of these waste products during bacterial metabolism.
CO2, acid, and alcohol
The Gram stain differentiates bacteria based on the structure of their _________.
Cell walls
Differential media is a type of specialty media which?
Contain specific dyes that cause a color change as different bacteria grow and produce waste products.
Which plate is the positive control in our transformation experiment (Part 1)?
Control 1 plate
The Gram staining procedure involves four key steps. Place them in the correct order.
Crystal violet, grams iodine (mordant), grams decolorizer (alcohol or acetone), safranin
What is the overall electrical charge of DNA and why?
DNA has an overall negative charge because of the many phosphate groups it contains.
The 3 stages of PCR, in order, are?
Denaturation, Annealing, Extension
The bacteria on the plate (below) is most resistant to which antibiotic?
Disc A
The bacteria on the plate (below) is most sensitive to which antibiotic?
Disc E
Which of the following genetic tests is a process that vividly paints chromosomes or portions of chromosomes with fluorescent molecules to identify chromosomal abnormalities?
FISH
The growth in this deep agar tube could best be described as?
Facultative
Is this the proper order to record a composite reaction for Kligler Iron agar? slant reaction/ H2S production/ base reaction/ gas production
False
It is not necessary to wash your hands BEFORE beginning a lab AND AFTER completing a lab.
False
The wearing of open-toed shoes is permitted in the microbiology lab.
False
Used culture materials (plates, swabs, inoculating loops, etc.) should be disposed of in the trash can.
False
Gram-positive bacteria stain pink.
False (it stains purple)
The material in the bacterial cell wall that confers rigidity and is responsible for retaining the stain and counter stain is phospholipid.
False (peptidoglycan)
Which of the following observations would suggest that a plate was inoculated with a pure (axenic) culture?
Isolated colonies are all white in color and about the same size
What is the clinical significance of using urea agar as a biochemical test?
It can be used to determine a urinary tract infection caused by many enteric bacteria.
Which of the following protocols must be followed for the collection of a biological specimen in order to obtain a timely and valid laboratory result?
It must be collected in the proper container, Collected samples must be transported to the laboratory as soon as possible, It must be correctly labeled in the presence of the patient, with 2 identifiers such as name and patient number, Samples must be collected using proper phlebotomy or tissue collection techniques.
Stating that "microorganisms are truly ubiquitous," most like means what?
Microorganisms can be found nearly everywhere.
Which two parts of a microscope combine to give a magnified view of a specimen on a slide?
Ocular Lens and Objective Lenses
This sequence of DNA could be best defined as a_____________?
Palindrome
Lactose, maltose, mannitol, sucrose, and trehalose are all different types of___________ and they are all used under the general heading of____________ testing.
Sugars, carbohydrate
SIM media is a multiple test media that displays several different possible reactions. What are the compounds or activities SIM is used to test for?
Sulfur, Indole, Motility
After 48 hours of incubation at 37oC you observe a red color in the Methyl Red media after adding 6 drops of the proper reagent. This means that_____________?
The bacteria are positive for the production of an acid
If both tubes of the OF Glucose media test are yellow after 48 hours of incubation, this means?
The bacteria can be considered both an oxidizer and a fermenter.
Why is the Gram stain method an important tool for a clinical microbiologist?
The gram stain method is important because it differentiates between gram-positive and gram-negative organisms. This helps classify and identify different microorganisms.
In a polymerase chain reaction there would be 4 strands after the first cycle and 8 strands after the second cycle. How many strands would be available after starting with the template strand and running 32 cycles?
There would be over 4 billion strands
When performing a serial dilution, a student forgot to change the pipette and used the same pipette for every 0.5 mL transfer of the solution from tube to tube. Would these results be accurate and what would you predict the outcome would be?
These results would be inaccurate because the extra culture on the inside and outside of the pipette would increase the concentration of the next tube beyond the factored amount.
What is the reaction of the carbohydrate fermentation test on the right? The uninoculated media is displayed on the left.
This test is positive for carbohydrate consumption with the production of CO2 gas.
What is this test used for and what is the reaction of the tube on the right?
This tests for the usage of an amino acid in the media and the tube on the right is positive.
Imagine that you forgot to flame the loop before streaking the inoculum from the first quadrant into the second quadrant. What is the most likely consequence of this error?
Too much bacterial growth outside of the first quadrant.
Clinical testing for biochemical genetic diseases utilize techniques that measure proteins and their activity level.
True
During the gram stain procedure, a mordant must be added to form insoluble products that help the bacterial cells retain the primary stain.
True
Eating of any kind (including gum chewing and mints) and drinking of any beverages are not allowed in the microbiology lab at any time.
True
Gram stained slides are not considered a biohazard waste and may be disposed of in the non-biohazard sharp (broken glass) container.
True
Gram staining is a differential stain.
True
Nucleotides can join together to form completed, functioning DNA molecules even if they are not from the same domain...such as Eukaryotic and Prokaryotic nucleotides.
True
The lab bench should be wiped down with disinfectant (bleach solution) BEFORE beginning a lab AND AFTER completing a lab.
True
Select all of the correct statements concerning this Kligler Iron Agar set for Tube A.
Tube A displays the same composite reaction as Tube D The bacteria in Tube A can use something other than O2 as a final electron acceptor Tube A displays the presence of H2S. Tube A displays a negative reaction on the slant and a positive reaction in the base.
This plate (below) was inoculated with a bacterial lawn and exposed to UV light for 90-180 seconds and then incubated for 48 hours. Is there visible evidence of DNA repair on this plate?
Yes, there is clear evidence of repair on the 90 second area demonstrated by numerous colonies.
Which of the following is a possible waste product produced by bacteria during the fermentation process?
a. Acid b. Carbon Dioxide c. All of the above d. Alcohol Answer: C-all of the above
Which of the following describes the proper microscope care and technique?
a. All of the choices are correct. b. At the end of the lab period is sure to cover the microscope before storing it. c. Always begin focusing on the lowest power lens available. d. Only use lens paper to clean the lenses of the microscope. e. Always carry the microscope upright, with one hand on the arm and the other under the base. Answer: A- all of the choices are correct
Which of the following could result in a Gram-positive bacteria staining Gram-negatively?
a. The organism itself. b. Overheating during heat fixation. c. Too much washing with water. d. The age of the culture. e. All of the choices are correct. Answer: E- all of the choices are correct
in indirect ELISA, what is added first to the microtiter well
antigen
In an ELISA procedure ___________ is placed in a microtiter plate then a patients __________is added to each well.
antigen; serum
Fundementally, immunological reactions involve interactions between_____________ and ______________?
antigens and antibodies
In the bacterial conjugation experiment (Part 2) we are trying to make both strains of bacteria resistant to________?
both antibiotics, streptomycin and ampicillin
beta hemolysis
clear zone in media, all RBC lysed and all nutrients are absorbed
what indicates the presence of the substance being tested for in the ELISA test
color change
carbon dioxide gas
displayed in carbohydrate fermentation
All plasmids exist as______________and contain______________?
double stranded DNA; specialized genes
Bacterial conjugation and plasmid mediated drug resistance is not really of concern to modern medicine since the rate at at which a conjugative plasmid can spread through a bacterial population is extremely slow.
false
ELISA testing requires living/growing cultures in order to be accurate.
false
The best overall method for sterilization is ultraviolet light due to its high penetrating ability.
false
When you have finished recording the results for this lab experiment the agar plates should be placed in the non-biohazard, non-sharp container.
false
this was a successful transformation experiment
false
The introduction of genes, usually by way of a viral vector, which are functioning normally into an individual with a genetic disease, such as sickle cell anemia, is known as.
gene therapy
Palindrome
identical sequence of DNA read the same way forward and backward
+ methyl red test
indicates acid production
presence of hydrogen sulfide
indicates that bacteria is not a strict aerobe
In a bacterial transformation experiment, the purpose of transferring the cultures into varying temperatures of hot and cold in order to make them permeable to extracellular DNA is known as?
inducing competency
primer
initiates DNA synthesis
alpha hemolysis
media is greenish, all RBC lysed but iron is not absorbed
gamma hemolysis
no change in media, no lysis of RBC
What variable(s) should be considered when choosing an appropriate disinfectant (choose all that apply)?
pH cost solubility
The acidity or alkalinity of an environment influences microbial growth. The optimal pH for growth of clinical significant bacteria usually occurs between _____________?
pH 6.5 and pH 7.5
While bacterial chromosomes normally carry all the genes necessary for growth and reproduction, bacteria also contain genes associated with extra-chromosomal DNA (such as antibiotic resistance) called?
plasmids
The Immunochromatographic Assay we will be performing to test for the presence of the Streptococcus bacteria is the same type of test you would use for_____________testing?
pregnancy
PCR
rapidly increase the amount of DNA in a sample
ferric chloride
reagent for phenylalanine
endonuclease
restriction enzyme
An agar plate has only one species of bacteria growing on it. This type of media can best be described as ___________________.
selective media
What is the purpose of mixing both strains of bacteria together on the test plate for the conjugation experiment?
so a sex pili can be formed between the two species and genetic information can be transferred
If there is growth (blue colonies) on the experimental plate after 48 hours incubation this means?
the bacteria are now resistant to ampicillin
A positive reaction for Citrate agar will appear as?
the color blue
Describe the reaction that generates the color in positive wells in the ELISA reaction.
the reaction between the patients serum and the known antigen indicating the patient has formed antibodies to the antigen
Ultraviolet light causes a specific mutation in nucleic acid, known as a?
thymine dimer
The purpose of a deep agar stab inoculation tube is _________.
to produce layers that vary in oxygen concentration
A "bacterial lawn" is an inoculation technique in which the bacterial sample is evenly distributed over the entire surface of the agar plate.
true
In a DNA microarray, many known DNA templates (of various genes or portions of genes) are used as genetic probes to collect complementary mRNA molecules from a sample, which can be used to measure gene expression of the sample.
true
In a disc diffusion test, the larger the zone of inhibition the greater the bacterial sensitivity to the drug.
true
True or False? The "OF" in the OF Glucose test stands for oxidation/fermentation.
true
Using salt or sugar as a preservative for food is reliant on the effect of dehydration (osmotic pressure) on bacteria.
true
Which of the following is considered a physical method for controlling microbial growth?
ultraviolet light
indole
waste product generated in the + peptone test
If the ELISA test is positive for exposure to HIV antibodies a color change will occur in the well.
yes
The composite reaction of Tube C is______________?
-/+/gas
List and describe three examples of specialty stains that were presented in the lab reading.
1. Acid-fast stain: this diagnosis tuberculosis and leprosy. An acid-fast stain remains red while the other remains blue. 2. Flagella stains: make the flagella appear thicker and easier to see under a microscope. Flagella are an important aspect of bacterial classification. 3. Capsule stain: stains the background and bacterial cell so a white surrounding (capsule) appears. Capsules are another important identifier for bacterial classification.
The porous electrophoresis gel allows the DNA to be______________so it can be compared to known DNA base pair sizes and distances traveled.
Separated by size
A method used to dilute a substance in a stepwise manner into a solution with a constant dilution factor is known as?
Serial dilution
