Exam Questions Essay

777 Words Nov 22nd, 2014 4 Pages
4. Compare and contrast gram-positive and gram-negative cell walls with regard to (a) sensitivity to antimicrobial agents, (b) resistance to phagocytosis, (c) chemical composition, and (d) decolorization by alcohol. Gram-positive bacteria differ from gram-negative bacteria in the structure of their cell walls. The cell walls of gram-positive bacteria are made up of twenty times as much murein or peptidoglycan than gram-negative bacteria. These complex polymers of sugars and amino acids cross-link and layer the cell wall. The thick outer matrix of peptidoglycan, teichoic acid, polysaccharides, and other proteins serve a number of purposes, including membrane transport regulation, cell expansion, and shape formation. Almost all bacteria can …show more content…
c. Used disposable syringe: Needles and syringes are essential tools for health care delivery. It’s disposable one time use so just throw it away. Use ethylene oxide if u must sterilize them first (which seems a bit unnecessary considering they have special bins for bio waste.
d. Tissues taken from patients: Gamma irradiation and gas sterilization with ethylene oxide can be used to sterilize human tissue taken from patients. The gas penetrates the tissue.
6. You look in the refrigerator and find an orange drink you had forgotten was there.
The drink now has an off-taste and it bubbles. What is the most likely explanation?
For the changes in the drink? The sugars in the drink might have become fermented by certain acidophilic bacteria or fungi, thus producing some other chemical compound such as pyruvic acid, lactic acid, ethanol etc... Fermentation most of the time gives CO2 as the by product that can be seen as bubbles. Fermentation is any large scale microbial process occurring with or without air. Furthermore, due to the fact that the orange has been opened or closed for a period of time without preservation, it starts to rot after a while because of the toxic acidic content. This increased CO2 concentration and sugar fermentation to other products gives off taste. The combination of bacteria, and the food source, being consumed has made the waste of the bacteria (alcohol) incorporated into the drink, giving it the

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