Questions and Problems

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Access to and use of the internet is assumed in answering all questions including general information, statistics, constants, and mathematical formulas required to solve problems. These questions are designed to promote inquiry and thought rather than just finding material in the text. So in some cases there may be several “right” answers. Therefore, if your answer reflects intellectual effort and a search for information from available sources, your answer can be considered to be “right.”

1. What are the basic building blocks of proteins, and how do they determine the primary structure of proteins?

2. What is meant by denaturation of proteins? Is it bad?

3. What are some major kinds of proteins?

4. What is the approximate simple formula of carbohydrates?

5. Fill in the blanks of the following pertaining to carbohydrates: Glucose is an example of a______________, sucrose is a ___________________________, and starch and cellulose areboth ___________________________.

6. How are lipids defined and how does this definition differ from that of other biomolecules?

7. What does DNA stand for? What are 6 specific ingredients of DNA?

8. Although lipids are defined by a physical property that they all share, what is a common characteristic of lipid structure?

9. From the structures given in Figure 7.5, what kind of functional group seems to be common in lipids?

10. How does the compatibility of lipids with organic substances, such as organochlorine compounds, influence the environmental behavior of such compounds?

11. What distinguishes RNA from DNA? How are they similar?

12. What are the three constituents of all basic units of nucleic acids?

13. Exposure of a person to toxic benzene can be estimated by measuring phenol in blood. Explain the rationale for such an analysis. Why is benzene epoxide not commonly determined to estimate benzene exposure?

14. Consider the toxicity of inhaled carbon monoxide in the context of Figure 7.14. Identify for carbon monoxide the receptor, the abnormal biochemical effect, and the physiological response manifesting toxicity.

15. What is the toxicological importance of lipids? How are lipids related to hydrophobic pollutants and toxicants?

16. What is the function of a hydrolase enzyme?

17. Match the cell structure on the left with its function on the right, below:

A. Mitochondria 1. Toxicant metabolism

B. Endoplasmic reticulum 2. Fills the cell

C. Cell membrane 3. Deoxyribonucleic acid

D. Cytoplasm 4. Mediate energy conversion and utilization

E. Cell nucleus 5. Encloses the cell and regulates the passage of materials into and out of the cell interior

18. The formula of simple sugars is C₆Η₁₂Ο₆. The simple formula of higher carbohydrates is C₆Η₁₀Ο₅. Of course, many of these units are required to make a molecule of starch or cellulose. If higher carbohydrates are formed by joining together molecules of simple sugars, why is there a difference in the ratios of C, H, and O atoms in the higher carbohydrates as compared to the simple sugars? What do these formulas suggest about the kind of enzyme that would be required to produce glucose from a higher carbohydrate such as cellulose?

19. What would be the chemical formula of a trisaccharide made by the bonding together of three simple sugar molecules?

20. The general formula of cellulose may be represented as (C₆H₁₀O₅)_x. If the molar mass of a molecule of cellulose is 400,000, what is the estimated value ofx?

21. Glycine and phenylalanine can join together to form two different dipeptides. What are the structures of these two dipeptides?

22. Fungi, which break down wood, straw, and other plant material, have what are called“exoenzymes.” Fungi have no teeth and cannot break up plant material physically by force. Knowing this, what do you suppose an exoenzyme is? Explain how you think it might operate in the process by which fungi break down something as tough as wood.

23. The straight-chain alcohol with 10 carbons is called decanol. What do you think would be the formula of decyl stearate? To what class of compounds would it belong?

24. In what respect is an enzyme and its substrate like two opposite strands of DNA?