Question

1. Briefly describe 2 possible effects that antibiotics have on bacteria (ie- 2 things antibiotics can do to the bacterial cell). Indicate whether each effect is bactericidal or bacteriostatic. 5pts (you may name a 3^rd effect for 1 extra credit point)

2. Would B cell activation occur in a person who has NO dendritic cells (DC)? Explain. 5pts

3. Is it a good idea to treat the flu with anti-bacterial antibiotics? Explain. 5pts

Answer 1

1 The antibiotic inhibits the cell wall synthesis in the bacteria so that it will become prone to the body immune reactions and will get ultimately killed or lysed .Example Beta lactam antibiotics like Pencillin inhibit the bacterial cell wall synthesis by inhibiting peptidoglycan synthesis . -BACTERICIDAL .Meaning it kills the bacteria

• Some antibiotics like Tetracycline,Clindamycin inhibit the protein synthesis by blocking tRNA binding to 30S ribosome -mRNA complex BACTERIOSTATIC meaning it does not kill the bacteria as such but reduces its multiplication and in total its population.
• Some antibiotics inhibit the nucleic acid synthesis .Antibiotics like Quinolones work by Inhibiting DNA gyrase which is required for supercoiling of DNA . - BACTERICIDAL.

2 Dendritic cells are referred to as the antigen presenting cells .They process antigen material and present it to the T cells of immune system.which then provides cytokine and cell bound help to B cells .Thus a person absent with dendritic cells there would be no antigen presentation to the T cell and the B cell.So if there is no T-cell activation indirectly will lead to inhibition of B cell activation .Thus dendritic cells are essential for both B and T cell activation.As B cells are activated by binding of antigen to its receptors present at its surface causing the B cell to proliferate and divide .Thus here the main step is the binding of the antigen to the receptor present at the Surface of BCell for this Dendritic cells must be present ,as they are the antigen presenting cells.Thus a person with no dendritic cell there will be no B cell activation.

3 Flu is a respiratory illness which is transmissable.The important point to note here is that Flu is caused by viruses .Antibiotics are used to treat bacterial infections and it wont show any effect to viruses as viruses are more complicated than bacteria and have different cellular organizations as compared to bacteria.Moreover if antibiotics are used to treat Flu it will cause more harm than good because of the side effects including death of the beneficial organisms of the gut and drug resistance.Thus flu should be treated with Antiviral drug and not by anti bacterial anti biotics