Humboldt State University ® Department of Chemistry

Richard A. Paselk

Biochemical Toxicology

Mid-Term Exam Questions - Final Version Spring 2010

  1. Discuss in detail the types of interactions expected between toxins and macromolecules and/or organelles in terms of the forces and bonds involved. Give examples to illustrate the different interactions.
  2. Discuss the dose-response relationship, including the meaning and usefulness of LD50, TD50 etc. Be able to find values for these quantities given various plots as we have seen. Be able to interpret the various plots of dose/response we have discussed (gaussian, sigmoidal, linear) and to find values appropriate to each (mean, median, standard deviation, LD50, etc.). You may need to interpret and/or draw plots for a question based on this material.
  3. Discuss the various modes of transport across biological membranes and their relative importance to the uptake of toxins.
  4. Discuss the various factors affecting the transport and ultimate distribution of toxins across a membrane. Include the effects of ionization and pH, and equilibrium versus steady state situations. Quantitative examples of equilibrium distributions are strongly encouraged.
  5. Discuss the distribution of toxic substances into various compartments, including in your discussion: a working definition of a compartment, the factors most important for a reasonable modeling of the distribution between compartments, the conditions for reasonably assuming equilibrium in the modeling, and the advantages of assuming single, multiple and physiologically based compartments.
  6. What reactions does the P450 system catalyze? Show how most of these reactions can be accounted for with a single mechanism (that is, they share essentially the same intermediate).

General: the midterm will consist of three to four of the above questions. You are allowed to bring a 4x6 card with information on it (both sides). I suggest outlining potential answers in advance, and putting key examples on your card for use during the exam.

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Last modified25 February 2010

© RA Paselk 2006