ngs Review View Help OTell me what you want to do a 7-A- _ _- $- 2 LE 1 . T Norm
ID: 147320 • Letter: N
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ngs Review View Help OTell me what you want to do a 7-A- _ _- $- 2 LE 1 . T Normal NO Spac .. Heading 1 Heading 2 Title Paragraph Styles A micro wall. The following results were attained after Bacillus cereus was exposed to drugs, A, B C, and biologist is testing a group of drugs to determine whether they affect the formation of the cell Percent No Drug Describe the experiment in terms of data being measured and controls that are used. Which drug(s) has an effect on cell wall construction? Give your reasoning for your answer. Which step(s) in cell wall construction is the drug most likely acting on? Explain your answer 100 90 80 70 60 50 40 30 20 10 0Explanation / Answer
Bacteria are cells surrounded by peptidoglycan cell wall and inner plasma membrane while there is an outer lipid bilayer in gram –ve. The cell wall synthesis is inhibited by specific anti-bacterial, which weakens the peptidoglycan scaffold in the bacterial cell wall. This leads to further destruction of the structural integrity of the cell wall.
Some antibiotics interfere with the synthesis of the basic peptidoglycan building block. They inhibit the enzymes involved in the precursor synthesis. In the cytoplasm, peptidoglycan synthesis occurs and muramyl pentapeptide is anchored through a water-soluble UDP glucosamine moiety.
Another antibiotic, blocks the enzymatic conversion of undecaprenyl phosphate to the lipid I intermediate inhibiting the completion of peptidoglycan structure. Beta-lactam antibacterial inhibits the transpeptidase enzymes and blocks the assembly of the peptidoglycan layer in gram +ve and gram –ve bacteria. Another antibiotic prevents the cell wall construction by interfering with transglycosylases.
The given figure shows that formation of extracellular N-acetyl glucosamine and N-acetyl muramic acid residues are more and used for the cell wall construction while their intracellular levels are very low, 80% and 20% respectively, when no drug is used.
In the case of drugs A and C, the situation remained the same as that of the case when no drug was used.
In the case of drugs B and D, the intracellular levels of NAM/NAG increased indicating that the formation and synthesis of chains to be used for cell wall construction is blocked. So, the internal levels of the molecules increased and the extracellular levels are reduced. This says that the drug is functional here by inhibiting the process of the material that is used for the cell wall construction.
Hence, B and D has a negative effect on the cell wall construction.
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