• 8. What does “parfocal” mean? Is the microscope used in the laboratory a “parfocal” microscope? Parfocal is that a microscope stays in focus when you change the objective lens.• Parcentric?• Stays center even after you change the focus.• Whats your TA’s Name and where to fid him.
• Know the difference between gram + and –• Know what the different reagents in the gram stain and what they accomplish.• Know what a basic (positive) and a acidic(negative) stain look like. And what they stain.
• Know all the media we used and what positive test means and what a negative test means. Also when a organism doesn’t grow what that means.• Know selective and deferential definitions.
• Macconkey agar• Positive means• If it grows it means• EMB• If it grows ?• If is positive?
• MSA (mannitol salt agar )• Positive means ?• Growth Means ?• Mitis – salavarius• Colonies are blue?• If no growth?• PEA• Grow means?
Stains• Positive stain• Stains the cell also known as the basic stain• Negative stain• Stains all the back ground not the cells themselves.• Differential stain?• Differentiates the cells some how due to a structure or some type of phenotype characteristics.• Capsule stain uses what 2 types of stains• Manevals stain• positive stain.• Congo red• Negative• Endospore stain uses what stains• Malachite green and safernin
EMB• A positive test means what ?• growth of Gram + organisms. Additionally, the medium contains lactose which can be utilized by lactose fermenters as a carbon and energy source.• Grow means its what ?• That it’s a gram -.
Macconkey’s• What does growth mean ?• That is a gram -• What does positive test mean?• above pH 8. Like EMB, this medium contains lactose and those organisms that can utilize lactose produce acids. The acid production results in a lower pH in the medium and a change in the color of the medium to yellow. Neutral red is the ph indicator• The selective molecule is bile salts
Hektoen enteric agar• MacConkey’s agar. However, this differs from MacConkey’s agar because it also has ammonium sulfate and sodium thiosulfate in it.• These chemicals are indicator molecules because they react with H2S released from the breakdown of peptones in the medium and turn the H2S producing colonies black (indicating that H2S was present).• The pH indicator in this medium is bromothymole blue.• When bacteria use the lactose and sucrose in the medium acid is produced and the medium’s color changes from a blue/green• It has bile salts as the selective indicator molecule
Mitis-salavarius• Grows up mainly gram positive mainly streptococcus.• If the colonies turn blue what does this mean?• It incorporates the trypan blue from taking in sucrose peptones and all the different carbohydrates.
Mannitol salt agar• IF an organims grows this means that the organism is a halophile.• If it changes color which is a positive test this means that the organism uses mannitol as its main carbon source.• has phenol red indicator.• It has NaCl as a inhibitory molecule.