Old Material Study Flashcards
What is the aseptic technique?
The technique of heating tools to keep them free of unwanted contaminants or microbes.
What is a chemically-defined media?
A culture medium whose exact chemical composition is known.
What is a complex media?
A medium which varies in composition from batch to batch.
What is the purpose of the streak plate technique?
To allow individual cells to grow into separate colonies so that they can be removed and subcultured for other experiments.
What is a sign of growth in broth or in agar?
In broth: turbidity
In agar: colonies
What is the formula for total magnification?
(ocular lens) x (objective lens)
What is the total magnification of oil immersion lens?
1000x
What is a smear preparation?
To preserve the structure of a specimen. This kills and fixes them to the slide.
What does heat fixation do?
Denatures enzymes, facilitates adherence to a slide, makes cells more permeable and preserves their structure.
What is a simple stain?
The use of only on reagent to color all cells the same color.
Why do you use a simple stain?
To allow for visualization of cell shape, size, and arrangement.
What is a direct, simple stain?
Stains the cell.
What is a negative simple stain?
Stains the background, not the cell.
What is a differential stain?
Multiple reagents are used to stain cells differently. Allows for differentiation of cells.
What are the reagents used for a gram stain?
Crystal violet, iodine, alcohol, and safranin.
How is G+ stained in a gram stain?
Crystal violet: violet
Iodine: violet
Alcohol: violet
Safranin: violet
How is G- stained in a gram stain?
Crystal violet: violet
Iodine: violet
Alcohol: clear
Safranin: pink
What is the purpose of iodine in the gram stain?
To adhere the violet color to the bacteria’s cell membrane.
In the endospore stain, what color do the endospores turn?
(using malachite green) Green.
In the endospore stain, what color do the vegetative cells turn?
(using safranin) Pink.
In the acid fast stain, AF+ turns what color?
Red/pink with each step.
In the acid fast stain, AF- turns what color?
Red/pink -> blue.
With the capsule stain, what occurs?
A white halo appears around the cell.
What type of stain is a capsule stain?
A differential stain.
What is a countable plate in the standard plate count technique?
30-300 colonies.
How do you calculate # CFU/ml?
CFUs x DF = #CFU/ml
How do you know if the transformation occurred?
The bacteria is glowing green (due to IPTF), and it grew in the media (+DNA).
What is the purpose of the heat shock step of a transformation?
It facilitates the entry of DNA into the bacterial cells. The membrane becomes permeable.
What was the purpose of the plate with IPTG?
It allows the expression of the GFP protein, which requires IPTG, to demonstrate differential gene expression.
What are the steps of the lytic cycle?
1) attachment
2) entry of phage DNA and degradation of host DNA
3) Synthesis of viral genomes and proteins
4) assembly
5) release
What is a plaque?
Visual clearings in a lawn of bacterial growth.
What is plaque assay used for?
To quantify the number of viruses.
What is a zone of inhibition?
The zone in which there is no visible bacterial growth around the antibiotic disk.
What is the name of the plate used for antimicrobial susceptibility testing?
Mueller-Hinton agar
What is the mm range for resistant bacteria?
less than or equal to 13 mm.
What is the mm range for susceptible bacteria?
14-16mm
What is the mm range for intermediate bacteria?
Greater than or equal to 17mm.
What is a transformation?
When a cell takes up and expresses a new piece of DNA.
What is the name of the species that contains mycolic acid in its cell wall?
Mycobacterium
What are the two endospore-formers that we learned?
Clostridium and Bacillus
Why would we need an old culture of endospore-formers for an endospore stain?
It ensures a stress environment, which is when endospores would likely appear.
What is transduction?
The transfer of DNA from one bacteria into another bacteria via a bacteriophage.
What is conjugation?
Transfer of DNA material via a pilus. Requires cell-to-cell contact.
What do lesions on a leaf indicate?
TMV infection.
