MMBB Lab – Microbiology – Flashcards
Unlock all answers in this set
Unlock answers| What is the process of destroying pathogens on surfaces or tissues called? |
| Disinfection |
True or False
If the object is being treated is lifeless, the compound is called a disinfectant? |
| True |
True or False
Disinfection is a sterilization method
|
| False |
| A compound used on living tissue is called? |
| Antiseptic |
True or False
Another term for our normal flora is called microbiota? |
| True |
| Coliforms will appear on Violet Red Bile Agar (VRB) as deep purple colonies versus non-coliform enterics. This means VRB is what kind of medium? |
| Differential |
True or False
To do a spread plate techniqe, you use your inoculating loop? |
| False |
| The correct way to insert a pipette into a pipette helper or bulb is? |
| With your hands toward the end of the pipette nearest helper. |
| After culturing and Gram staining organisms from our hand washing experience, you find lots of Gram positive bacteria and yeast an da few Gram negative bacteria. The Gram positive bacteria and yeast are more likely? |
| Residents |
| Plate count agar is what type of medium? |
| All Purpose |
| Why can bacterial cells be readily stained with basic dyes? |
| They contain an abundance of anionic ribonucleic acid in their ribosomes |
| This rigid bacterial structure is responsible for maintaining cell shape under various osmotic conditions |
| Peptidoglycan cell wall |
| What is the difference between a simple and differential stain? |
Simple stains use one dye; differential stains use more than one dye
Simple stains show all bacteria as the same color; differential stains differentiate between different kinds of bacteria |
True of False
A Gram stain is a type of differential stain? |
| True |
| What is (are) used when performing a Gram stain? |
Iodine Crystal Violet 95% Alcohol Safranin |
| After performing a Gram stain, a Gram positive cell will appear _______ and a Gram negative cell will appear ______ under the microscope? |
Purple Pink |
| A Gram negative organism we looked at in this lab was? |
| Escherichia coli |
True or False
The pink color of a bacterial cell after a Gram stain is due to Safranin? |
| True |
True or False
Gram negative cells have thick peptidogylcan walls? |
| False |
| Why do we heat fix our slides before performing the Gram stain? |
| This denatures the proteins slightly, allowing the cells to remain attached to the slide during Gram reaction |
True or False
Sterile means that no living organisms are present? |
| True |
True or False
A beaker full of water should be autoclaved with the Fast/Gravity cycle? |
| False |
| Two essential factors of heat sterilization are? |
Time Temperature |
| What is the term for the factor that influences the time required for sterilization in an autoclave? |
| Load |
| Name two spore formers? |
Bacillus subtilis Bacillus stearothermophilus |
True or False
Heat causes the coagulation of proteins, which kills microbes? |
| True |
| What allows the temperature higher than 100 deg Celcius during sterilization in an autoclave? |
| Pressure |
True or False
A dry heat oven takes more time and higher temperature to achieve proper sterilization? |
| True |
True or False
Egg whites coagulate much more quickly in an oven than in boiling water. |
| False |
| What property of the genus Bacillus makes these organisms difficult to kill? |
| They form heat-resistant endospores |
True of False
Optical density will give you information about dead cells? |
| True |
| What happens to cells mixed with tempered agar in a viable plate count procedure if the water bath was at 95 degress Celcius instead of 60 degress Celcius? |
| Cells could die |
True of False
When determining bacterial numbers an accurate volume measurement is required? |
| True |
True of False
CFU stands for cell forming units? |
| False |
| A dilution to 10-6 is equal to? |
| 1/1,000,000 |
True of False
Samples that are too turbid cannot be measured accurately by a spectrophotometer? |
| True |
| When counting plates, you should only count the plates with how many colonies? |
| 25 - 250 colonies |
True of False
When doing plate dilutions, you can use the same pipette if you start with the most concentrated sample and work to the most diluted? |
| False |
| When using the spectrophotometer in the "Determining Bacterial Numbers" lab, we were measuring what? |
| Absorbance |
| A serial dilution involves what? |
| Making one dilution from the orginal culture and using that dilution to make the next dilution and so on |
True of False
A human's normal flora usually causes disease and sickness? |
| False |
True or False ; The streak dilution technique is commonly used in a clinical setting to isolate and identify pathogens? |
| True |
| In the streak dilution lab, we isolated colonies from a mixture containing which organisms? |
Escherichia coli Staphylococcus epidermidis Serratia marcescens |
| After using a swab to take a sample, it gets disposed of in the what? |
| Biohazard Bag |
| What is a bacterial colony? |
| Millions of cells derived from one bacterial cell on an agar surface |
True of False ; To help identify an unknown bacterium, a gram stain should be performed from a single colony? |
| True |
True or False ; A mixed broth can be used for a Gram stain procedure when trying to identify one bacterial species? |
| False |
| Blood Agar is? |
Nutrient Rich ; Typically used in the analysis of hemolytic bacterial organisms |
True or False ; We use sterile swabs when taking samples from the mouth, but not when taking samples from the environment; such as surfaces in the class? |
| False |
True or False ; The goal of a streak dilution is to obtain isolated colonies? |
| True |
| What is an Aniline Dye? |
| Synthetic organic dyes made from coal-tar products and are used routinely to stain bacterial cells so that the contours of the microorganisms can be clearly seen under the microscope. |
| Acidic Dyes contain what charge of molecule? |
| Anions |
| Anilines dyes can be? |
Acidic Basic Neutral |
| Basic dyes contain what charge of molecule to combine with anions and form salt? |
| Free Cations |
| How are neutral stains made? |
| By combining acidic and basic dyes and are generally used to stain cells from more complex organisms |
| What are the results of a viable plate count reported as? |
| "Number of colony-forming units per milliliter" (CFU/ml) |
True of False ; Temperature, time, and pH will all affect the ability of a particuluar chemical to kill a particular pathogen |
| True |
| Define Disinfectant? |
| Chemicals that kill pathogenic microorganisms while in contact with them. |
