Flashcards in Review, Midterm Lab Exam Deck (17):
Bacterial proteins (peptidoglycan) are coagulated and fixed to the glass surface.
Positively charged Chromagen (nucleic acid's and certain cell wall components carry a negative charge) strongly bind to the cationic chromogen (simple staining indicates morphology and arrangement) Crystal violet, methylene blue.
Negatively charged chromogen will not penetrate cells because of the negative charge on the surface of bacteria. Unstained cells against colored background. Negrosin
Alcohol increases the porosity of the cell wall by dissolving the lipids in the outer layer and dehydrating proteins. CV – I complex can be removed from the thinner and less highly cross-linked peptidoglycan layer. Which facilitates release of the unbound CV – I complex. Grams positive cells with their thicker peptidoglycan retain CV – I.
Graham negative cells
Dehydrating effect of alcohol reduces pores so CV – I is retained. Stain is difficult to remove.
Morphology and arrangement – basic dyes positively charged chromogen
Smear, mix with water, air dry, heatfix, stain, one minute, water, blot.
Also simple stain
These are metabolically inactive, highly resistant to unfavorable conditions (exhaustion of carbon source). Impervious layers called spore coats. Resist damage by heat, freezing, desiccation, radiation, and microbiological stains. May germinate later into vegetative cell. Not reproduction.Malachite green
# of Colonies x milliliters x dilution factor = cells per milliliter
Calculating cells per mill
Thick peptidoglycan (cell wall) lattice over plasma membrane. Peptidoglycan = Nam plus nag carbohydrates. Proteins cross-link and anchor peptidoglycan into plasma membrane.
Gram + bacterial cell wall
Cell wall consists of (outer membrane & peptidoglycan) over plasma membrane. Phospholipid/peptidoglycan sandwich.
Graham - bacteria cell wall
Obligate aerobes. Obligate anaerobes. Facultative anaerobes.
Be familiar with test tube arrangement.
Produces a characteristic change in the appearance of bacterial growth and medium surrounding the colonies which permits differentiation. Eosin – methylene blue auger
Designed to isolate specific groups of bacteria. incorporates chemical substance that inhibits the growth of one type of bacteria while permitting the growth of another Facilitating bacterial isolation. 7.5% sodium chloride auger
In blood agar (and enriched media) alpha hemolysis is the incomplete lysis of red blood cells with reduction of hemoglobin to methemoglobin resulting in a greenish halo around the bacterial growth. Beta hemolysis is the lysis of red blood cells with the complete distruction and use of hemoglobin resulting in a clear zone surrounding the colonies.
The difference between alpha and beta hemolysis
Fermentation is a biooxidative process not requiring oxygen in which an organic substrate serves as the final electron acceptor. Aerobic respiration is biooxidation in which molecular oxygen can serve as the final electron acceptor.
Main difference between aerobic respiration and fermentation