MCB 229 Spring 2000 Study Guide 19 Prof. Terry

Covers Lecture for April 20

This study guide is intended for you to use while you are doing the assigned text reading. Quiz questions will be made with reference to topics in this study guide. Quiz #19, based on questions from this study guide, must be completed by midnight before the class on Thursday, April 20. You will need to create your "myWebCT" account and visit the MCB 229 WebCT page in order to access this quiz.

Chapter 29 (pp. 581-591). Parasitism. Mechanisms of pathogenicity.
  1. What is parasitism? Note that in ordinary usage the word "parasite" refers only to protist and helminth infections, although of course viruses, certain bacteria and fungi are also parasitic.
  2. What is meant by the following terms: endoparasite, ectoparasite, intermediate host, transfer host, reservoir host?
  3. What does the term "pathogen" refer to? Can an organism be parasitic and not pathogenic? If so, give an example.
  4. What 3 factors determine the outcome of a host-parasite relation?
  5. What is an "endogenous disease"? Who is most susceptible? What is a "vector"? A "fomite"?
  6. What does the term "virulence" refer to? What are the three characteristics that promote virulence? Can you have a virulent pathogen that only displays one of these 3 characters? If so, give an example. What is meant by "toxigenicity"? What is an LD50?
  7. Table 29.2 lists a lot of terms that describe different types of infections. You don't need to memorize all these terms, but do know the meaning of the following: abcess, acute, bacteremia, chronic, fulminating, latent, localized, nosocomial, opportunist, sepsis, septicemia, systemic, zoonosis.
  8. Adherence: what bacterial cell components promote specific adherence to host tissues? (see Table 29.3 and Fig. 29.3)
  9. What is the difference between invasiveness and intoxication?
  10. To what class of molecules do exotoxins belong? What are the type properties of exotoxins?
  11. Botulism is caused by a powerful exotoxin. Assume that a certain food has a small quantity of botulin toxin; if this food were boiled for 10 minutes, would it be safe to eat? Why or why not?
  12. What is an antitoxin? A toxoid?
  13. Table 29.5 lists some important bacterial toxins. For each of the following, be able to identify (a) the organism that produces this toxin, (b) where the toxin gene resides, (c) the type of enzymatic activity, and (d) the biological effect: anthrax, botulinum, cholera, diphtheria, shiga, tetanus. Note that this table is already in error: cholera toxin, thought to be located on the chromosome, has recently been shown to reside on a lysogenic phage.
  14. What is the difference between neurotoxins, enterotoxins, and cytotoxins? For the toxins in the previous list, which of these terms applies?
  15. To what class of molecules do endotoxins belong? What are the type properties of endotoxins?
  16. How do endotoxins cause disease?
  17. What are leukocidins and how do they affect host cells? What about hemolysins? What is streptolysin-O?