You are in a hurry and you spill a culture of pathogenic bacteria on your bencht
ID: 135681 • Letter: Y
Question
You are in a hurry and you spill a culture of pathogenic bacteria on your benchtop in the lab. You spray the area with 10% bleach and immediately wipe it up before going to your next class. Do you think you disinfected the area and killed off the pathogen properly? Explain your reasoning. 5. 6. Why do you think there is a difference in the sensitivity of the 2 organisms tested with the various chemicals? (HINT: S. aureus is Gram positive and E.coli is Gram negative, think about the difference in the structures of the cell walls)Explanation / Answer
5] Bleach has been used as a cleanser and disinfectant for ages. It is an effective disinfectant and has been found to kill some of the most dangerous bacteria like staphylococcus, E.coli and salmonella. It also kills some viruses-- like those which cause common cold and influenza.
The active ingredient contained in bleach is hypochlorite and it has the same effect on bacterial proteins as heat. These proteins are necessary for bacterial growth and proliferation and if these proteins are affected by the bleach, then naturally the bacteria will die.
Since most bacterial cultures grown for study and research in a laboratory are of the above-mentioned classes, we can safely assume that the 10% bleach will be effective and will disinfect the area.
6] Gram-positive bacteria have a thicker cell wall as compared to gram-negative bacteria. The cell walls in both are made-up of peptidoglycan but in gram-positive bacteria, it consists of several layers of peptidoglycan while in gram-negative bacteria, it is composed of only a single layer of peptidoglycan surrounded by a an outer cell membrane. In gram-positive bacterial cell-wall, teichoic acids are absent.
Because of the thick peptidoglycan layer, the gram-positive bacteria stain a deep purple with gram dye.
On the other hand, gram-negative bacteria will stain red because the thin peptidoglycan layer is surrounded by the plasma membrane.
Penicillin and cephalosporins are antibiotics that inhibit bacterial cell wall formation and thus prevent the growth of bacteria
Because of this difference in the cell wall composition of the two categories of bacteria, their response to different chemical agents is not the same.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.