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MMBB Lab
Exam #2
58
Microbiology
Undergraduate 3
04/01/2012

Additional Microbiology Flashcards

 


 

Cards

Term
What is the process of destroying pathogens on surfaces or tissues called?
Definition
Disinfection
Term

True or False

 

If the object is being treated is lifeless, the compound is called a disinfectant?

Definition
True
Term

True or False

 

Disinfection is a sterilization method

 

Definition
False
Term
A compound used on living tissue is called?
Definition
Antiseptic
Term

True or False

 

Another term for our normal flora is called microbiota?

Definition
True
Term
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?
Definition
Differential
Term

True or False

 

To do a spread plate techniqe, you use your inoculating loop?

Definition
False
Term
The correct way to insert a pipette into a pipette helper or bulb is?
Definition
With your hands toward the end of the pipette nearest helper.
Term
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?
Definition
Residents
Term
Plate count agar is what type of medium?
Definition
All Purpose
Term
Why can bacterial cells be readily stained with basic dyes?
Definition
They contain an abundance of anionic ribonucleic acid in their ribosomes
Term
This rigid bacterial structure is responsible for maintaining cell shape under various osmotic conditions
Definition
Peptidoglycan cell wall
Term
What is the difference between a simple and differential stain?
Definition

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

Term

True of False

 

A Gram stain is a type of differential stain?

Definition
True
Term
What is (are) used when performing a Gram stain?
Definition

Iodine

Crystal Violet

95% Alcohol

Safranin

Term
After performing a Gram stain, a Gram positive cell will appear _______ and a Gram negative cell will appear ______ under the microscope?
Definition

Purple

Pink

Term
A Gram negative organism we looked at in this lab was?
Definition
Escherichia coli
Term

True or False

 

The pink color of a bacterial cell after a Gram stain is due to Safranin?

Definition
True
Term

True or False

 

Gram negative cells have thick peptidogylcan walls?

Definition
False
Term
Why do we heat fix our slides before performing the Gram stain?
Definition
This denatures the proteins slightly, allowing the cells to remain attached to the slide during Gram reaction
Term

True or False

 

Sterile means that no living organisms are present?

Definition
True
Term

True or False

 

A beaker full of water should be autoclaved with the Fast/Gravity cycle?

Definition
False
Term
Two essential factors of heat sterilization are?
Definition

Time

Temperature

Term
What is the term for the factor that influences the time required for sterilization in an autoclave?
Definition
Load
Term
Name two spore formers?
Definition

Bacillus subtilis

Bacillus stearothermophilus

Term

True or False

 

Heat causes the coagulation of proteins, which kills microbes?

Definition
True
Term
What allows the temperature higher than 100 deg Celcius during sterilization in an autoclave?
Definition
Pressure
Term

True or False

 

A dry heat oven takes more time and higher temperature to achieve proper sterilization?

Definition
True
Term

True or False

 

Egg whites coagulate much more quickly in an oven than in boiling water.

Definition
False
Term
What property of the genus Bacillus makes these organisms difficult to kill?
Definition
They form heat-resistant endospores
Term

True of False

 

Optical density will give you information about dead cells?

Definition
True
Term
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?
Definition
Cells could die
Term

True of False

 

When determining bacterial numbers an accurate volume measurement is required?

Definition
True
Term

True of False

 

CFU stands for cell forming units?

Definition
False
Term
A dilution to 10-6 is equal to?
Definition
1/1,000,000
Term

True of False

 

Samples that are too turbid cannot be measured accurately by a spectrophotometer?

Definition
True
Term
When counting plates, you should only count the plates with how many colonies?
Definition
25 - 250 colonies
Term

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?

Definition
False
Term
When using the spectrophotometer in the "Determining Bacterial Numbers" lab, we were measuring what?
Definition
Absorbance
Term
A serial dilution involves what?
Definition
Making one dilution from the orginal culture and using that dilution to make the next dilution and so on
Term

True of False

 

A human's normal flora usually causes disease and sickness?

Definition
False
Term

True or False

 

The streak dilution technique is commonly used in a clinical setting to isolate and identify pathogens?

Definition
True
Term
In the streak dilution lab, we isolated colonies from a mixture containing which organisms?
Definition

Escherichia coli

Staphylococcus epidermidis

Serratia marcescens

Term
After using a swab to take a sample, it gets disposed of in the what?
Definition
Biohazard Bag
Term
What is a bacterial colony?
Definition
Millions of cells derived from one bacterial cell on an agar surface
Term

True of False

 

To help identify an unknown bacterium, a gram stain should be performed from a single colony?

Definition
True
Term

True or False

 

A mixed broth can be used for a Gram stain procedure when trying to identify one bacterial species?

Definition
False
Term
Blood Agar is?
Definition

Nutrient Rich

 

Typically used in the analysis of hemolytic bacterial organisms

Term

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?

Definition
False
Term

True or False

 

The goal of a streak dilution is to obtain isolated colonies?

Definition
True
Term
What is an Aniline Dye?
Definition
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.
Term
Acidic Dyes contain what charge of molecule?
Definition
Anions
Term
Anilines dyes can be?
Definition

Acidic

Basic

Neutral

Term
Basic dyes contain what charge of molecule to combine with anions and form salt?
Definition
Free Cations
Term
How are neutral stains made?
Definition
By combining acidic and basic dyes and are generally used to stain cells from more complex organisms
Term
What are the results of a viable plate count reported as?
Definition
"Number of colony-forming units per milliliter" (CFU/ml)
Term

True of False

 

Temperature, time, and pH will all affect the ability of a particuluar chemical to kill a particular pathogen

Definition
True
Term
Define Disinfectant?
Definition
Chemicals that kill pathogenic microorganisms while in contact with them.
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