Revision Questions- Sem 31. The lymphoid system is comprised of primary and secondary lymphoid organs. Briefly describe the processes which occur in:

(i) Primary Lymphoid Organs (5 marks)

(ii) Secondary Lymphoid Organs (5 marks)

2. Provide a brief summary of the role of the innate immune system in defense against invading pathogens (10 marks)

3. List the key characteristics of an acquired (adaptive) immune response (10 marks)

4. Briefly outline the immunological processes involved in the establishment of immune memory (10 marks)

5. List the roles of complement in immune defense (10 marks)

6. The uncontrolled activation of complement is deleterious. How is complement activity regulated normally (10 marks)

7. Why is immune tolerance important for survival of the individual? (10 marks)

8. What is the difference between central and peripheral T-lymphocyte tolerance? (10 marks)

9. List the major components of immune defense at mucosal sites (10 marks)

10. Describe the mechanisms for antigen processing and presentation via MHC class I and class II molecules to T lymphocytes. How do these different pathways lead to appropriate defences against different types of microorganisms? (15 marks)

11. Outline the immune response observed following primary and booster immunization 1 month later with tetanus toxoid. Include in your answer a comment on what you consider to be a protective immune response against tetanus. (15 marks)

12. In the normal healthy person, how is tolerance against self antigens and cross reacting antigens maintained? (25 marks)

13. Briefly explain the difference between autotrophs and heterotrophs in regards to energy conservation and carbon source. (4 points)

14. A very demanding (and forgetful) research professor asked you the culture the bacterial organisms he is working on. He did not leave any media behind for the organisms before he left for the meeting of mad scientists. But he did leave behind a description of their trophs. Organism A = psychrophilic, barophile, aerotolerant, fastidious, alklaphile. Organism B = thermophilic, acidophilic, obligate anaerobe, non-fastidious. Describe the type of media and conditions you will grow these organisms with. (4 points)

15. List the three major ways of maintaining (saving) cultures. (3 points)16. Compare between exotoxin and endotoxin (10 marks)17. CASE STUDYA 6-year old child is complaining of superficial spreading crusty lesions on his face. A culture of his skin lesions on blood agar showed numerous colonies surrounded by a zone of beta haemolysis. A gram stained film from the colonies showed Gram positive cocci arranged in bunches.

A What is your probable diagnosis?

B What is the causative organism?

C Mention the laboratory tests required to confirm the diagnosis.

18. Describe the epidemiological and clinical characteristics of sexually transmitted Chlamydia trachomatis infection. Describe the factors that should be considered in establishing a screening programme for this infection, and the diagnostic options available.

19. Your district general hospital has several endoscopy units on site with different procedures for decontamination. You have therefore been asked to review and standardise endoscopy decontamination services. Give recommendations based on best practice guidelines.

20. What are the main factors determining the prevalence of Methicillin Resistant Staphylococcus aureus infection in secondary and tertiary hospitals today? What measures would you recommend at the national level in order to reduce its prevalence?21. Write short notes for the following:

Pathogenicity mechanisms in E. coli

Listeria monocytogenes Strategies to prevent group B Streptococcal infection in Neonates

Salmonella typing

S. pyogenes pathogenesis

Neisseria meningitides vaccines

Pneumococcal conjugate vaccines

22. List the similarities and differences between passive diffusion and facilitated diffusion.

23. Explain the structure and symmetry of bacterial cytoplasmic membranes as suggested by the Fluid Mosaic Model. List the biochemicals that are present in or attached to the cytoplasmic membranes of microorganisms.

24. Diagram and name four mechanisms bacteria use to transport materials across the cytoplasmic membrane. Note when energy and additional compounds are necessary for any of these mechanisms to operate.

25. Give two other names for bacterial capsule and list five functions proposed for it.

26. Give four lines of evidence that support the Endosymbiotic Theory of the origin of eukaryotic cells.

27. Carl Woese suggested a phylogenetic classification scheme in 1980 that contained how many domains? Name these domains and explain how the relationships in his universal phylogenetic tree were determined.28. (A) Diagram a Gram-positive and Gram-negative bacterial cell wall. (B) Demonstrate the differences in the chemical structure of these two types of bacterial cell walls. (C) Where and when does penicillin affect bacterial cells? (D) Explain how autolysins affect the cell walls of Gram-negative bacteria and mycoplasmas.

29. Write short notes for the following:

Write the contributions of Pasteur and Beijerink.

Explain briefly the structure and functions of bacterial cell wall.

Briefly explain the concept of containment facility.

Write a commonly used method for isolation of pure culture of bacterium.

Distinguish between bacteria and mycoplasmas.