Exam 1 - Ch.4 - Microscopy, Staining, and Classification Flashcards
The shortest distance between two points on a specimen that can still be distinguished by the observer as separate entities.
Resolution
Differences in intensity between two objects, or between an object and background.
Contrast
What increases contrast?
staining
What is important in determining resolution?
contrast
What is staining?
Increasing contrast and resolution by coloring specimens with stains/dyes.
What must happen to a smear of microorganisms (thin film) prior to staining?
Must be fixed with heat!
What two types of stains are used for Gram staining?
Crystal violet and safranin
What color does safranin stain?
Magenta/red
What two stains are used for an acid-fast stain?
Carbon fuchsin and methylene blue
Carbon fuchsin stains what color?
Bright fire-engine red
What stains are used for an endospore stain?
Malachite green and safranin
What are the three steps in Gram staining?
1) crystal violet stain
2) decolorize with alcohol
3) counterstain with safranin
What happens during the decolorization step in Gram staining?
Purple is washed from the Gram (-) cells.
Why does the alcohol was the color from the Gram (-) cells?
Because the walls are thinner.
The safranin colors which cells in Gram staining?
Gram (-)
The purple colors which cells in Gram staining?
Gram (+)
What are mycobacteria?
A group of bacteria that do not have the typical peptidoglycan cell walls.
Mycobacteria cell walls have high what?
Waxy mycolic acid content
What makes Mycobacteria resistant to decolorization by acids during staining procedures?
They high waxy mycolic acid content.
Mycobacteria of referred to as what?
Acid-fast bacteria
What are the 3 steps in acid-fast staining?
1) carbon fuchsin primary stain
2) decolorixze (alcohol)
3) counterstain with methylene blue
What happens when you decolorize during step two of acid fast staining?
Acid-fast cells retain their red color because the acid cannot penetrate the waxy wall.
Mycobacteria stain what color?
Bright red
Red are what types of cells
Acid-fast cells/mycobacteria
What stains blue?
Non-acid fast cells like human cells and tissue. (any cell NOT Mycobacteria).
What are the three steps in endospore staining?
1) malachite green primary stain
2) decolorize with water
3) counterstain with safranin
What is important in the first step of endospore staining with malachite green?
Use heat to drive into endospore.
What color do the endospores color?
Green
What color do non-endospores color?
Magenta/red vegetative cells (non-endospore)
Gram (+) bacteria genus names usually end in what?
-um and -us
What are the exceptions to Gram (+) genus names (ending in -um and -us)?
Listeria
Nocardia
Actinomyces
Steptomyces
Listeria bacteria causes what?
Food poisoning
Nocardia causes what?
lung abscesses
Actinomyces causes what?
Oral abscesses
Streptomyces is important in what?
Important source of antibiotics
Gram (-) bacteria genus names usually end in what?
-a and -er
What are the exception to a Gram (-) ending in -a or -er?
Pseudomonas
Proteus
vibrio
haemophilus
What does the bacteria pseudomonas cause?
Pneumonia, burn infections
What does Proteus cause?
UTIs
What does vibrio cause?
cholera
What does haemophilus cause?
Meningitis in children
What are some types of Mycobacteria?
Tuberculosis
Leprosy
buruli ulcer
What is an acid-fast bacteria?
mycobacteria
What will a bacteria with no cell wall stain in Gram staining?
It will stain red in Gram-stain
When a bacteria with no cell wall is grown on media what does it look like?
Forms distinctive “fried egg” appearance
Bacteria with no cell wall must colonize in what types of habitats?
In osmotically protected habitats such as animal or human bodies.
Give an example of a bacteria with no cell wall?
mycoplasma
What does mycoplasma cause?
pneumonia
What is the classification and identification of microorganisms called?
taxonomy
What is Linnaeus?
System classifying organisms based on characteristics in common.
What type of nomenclature is used?
Binomial nomenclature
What does binomial nomenclature look like?
Genus species (in italics, first part capitalized)
Who compared nucleotide sequences of rRNA subunits in classifying bacteria?
Carl Woese
What 3 domains did Carl Wiese propose as determined by rRNA sequences?
eukarya
Bacteria
archaea
Bacteria and archaea are what types of cells?
prokaryote
What are the five types of eukarya?
Animals Plants Fungi Protozoan algae
What is acellular?
Viruses
What are helminths technically labeled?
Eukaryotes - animal
helminths are worms
What is a type of taxonomic key?
Dichotomous keys
What are dichotomous keys?
A series of paired statements where only one of two “either/or” choices applies to any particular organism.
How do the dichotomous keys work?
Key directs user to another pair of statements, or provides name of organism.
What is the end point of a dichotomous key called?
Terminal key
