Lab 2 Flashcards
Colony morphology
Characteristic of a colony (size, shape, color, texture) that differs based on species..
Define colony
Cluster of bacteria cells growing on solid media (individual cells).
Define Lawn
Complete growth of bacteria with no present individual colonies.
What is a margin?
A shape of the edge of the colony.
What is the difference between bacterial and fungal colonies?
Bacterial colonies are usually small with defined margins whereas fungal colonies are usually large with a fuzzy or powdery appearance.
What is the purpose of streak plate?
To isolate bacterial colonies to obtain a pure culture.
What zone do you expect most and least colonies?
Zone 1 will have the highest concentration and Zone 4 and 5 will have the lowest concentration of colonies.
Why do you flame your loop before streaking the next zone on the plate?
We flame the loop before streaking the next zone to prevent contamination and reduce the number of bacteria on the plate.
What is used to view endospores produced by gram positive bacteria?
Spore stain (differential stain)
Gram positive bacteria have what?
Have thick cell wall and retain the crystal violet (staphylococcus aureus).
Gram negative have what?
Have thin cell wall and don’t retain the crystal violet-iodine complex and are stained pink (Escherichia coli).
In gram stain what is the primary stain?
Crystal violet
In gram stain what is the secondary stain?
Safranin
In gram stain what is the mordant
Iodine- helps to fix the stain.
In gram stain what is the Decolorizer?
Ethyl alcohol (removes stain that is not fixed).
What is simple stain?
Uses only one staining dye to visualize cells with single color.
What is differential stain?
Uses two or more staining dyes to visualize cells with more than one color (primary stain/secondary stain)
What are examples of simple stain?
basic dye (crystal violet, safranin, methylene blue)
What are examples of differential stain?
acidic dye (spore stain, capsule stain, and acid-fast stain)
Gram-positive bacteria produce endospores under adverse conditions, True or False?
True.
what stain are used for spore stain?
Malachite green (primary stain) is driven into the spore utilizing heat.
Safranin (secondary stain) is used to stain the vegetative cell.
What are capsules?
Extracellular structures produced by bacteria that allows them to adhere to surfaces.
Stains used and their purpose (capsule stain)?
Nigrosin (primary stain) and acidic dye that is used to stain the capsule background.
Safranin (secondary stain) is used to penetrates the capsule and stains the cell surface/bacteria.
What is the purpose and function of bacterial capsule?
Acid fast are red/pink, non-acid fast stain blue. What stains are used in the process resulting the different outcomes?
Carbol funchsin: purple (primary stain)
Methylene blue (secondary stain)
Acid alcohol (decolorizer)
What is used for bacteria containing waxy lipids (Mycolic acids) in their cell wall?
Mycobacterium
