© 2010 Pearson Education, Inc. Clicker Questions for use with Classroom Response Systems Campbell Essential Biology, Fourth Edition – Simon, Reece, and Dickey Campbell Essential Biology with Physiology, Third Edition – Simon, Reece, and Dickey Questions prepared by Brad Williamson, updated by Mike Tveten Chapter 3 The Molecules of Life

© 2010 Pearson Education, Inc. Concept Check This lysozyme protein molecule is found in tears and protects the eye from bacterial infections. Which of the following best describes the outside of the molecule? a.Mostly hydrophobic side groups are on the surface of the molecule. b.Mostly hydrophilic side groups are on the surface of the molecule. c.The side groups on the exterior of the molecule are mostly nonpolar. d.The side groups on the exterior are constantly changing between nonpolar and polar as the protein chain bends and folds.

© 2010 Pearson Education, Inc. Concept Check When proteins are heated, they usually denature. If moderate heat were applied to this molecule of DNA, what part of the molecule would break down or break apart first? Use your knowledge of chemical bonds. a.The nucleotides along each side would break apart. b.The sugar-phosphate backbone would separate from the nitrogen bases. c.The nitrogen base pairs would separate in the interior of the molecule.

© 2010 Pearson Education, Inc. Interpreting Data The amino acid side groups interact to create the three- dimensional structures of proteins. Some amino acids have hydrophilic side groups, whereas others have hydrophobic side groups. Of the hydrophilic groups, some are acids and others are bases. Acid side groups end with a carboxyl group. Basic side groups end with an amine group.

© 2010 Pearson Education, Inc. Interpreting Data The key to a protein’s function is its shape. The shape can be altered (or denatured) under unfavorable conditions. The pH of the solution is an important factor in determining protein shape. Depending on the pH of the solution, carboxyl groups and amine groups may or may not be charged. -COOH -COO - -NH 2 - NH 3 +

© 2010 Pearson Education, Inc. Interpreting Data This graph indicates how the charge on an amino acid “R” group can be determined by the pH of the solution. The green line across the middle of the graph represents the neutral pH of most cells. At neutral pH (7), which of the following amino acids carries a charge? a.aspartic acid b.glutamic acid c.lysine d.all of the above

© 2010 Pearson Education, Inc. Interpreting Data At an acidic pH of 3, which of the following amino acids carries a charge? a.aspartic acid b.glutamic acid c.lysine d.all of the above

© 2010 Pearson Education, Inc. Interpreting Data At a basic pH of 12, which of the following amino acids carries a charge? a.aspartic acid b.glutamic acid c.lysine d.both a and b

© 2010 Pearson Education, Inc. Biology and Society Looking for additional competitive advantage, some athletes have turned to anabolic steroids to enhance their performance. Due in part to the downsides of steroid use, most sports organizations ban the use of steroids. This controversy has played a large role in the Olympics. Do you agree that organizations such as the IOC should ban the use of performance-enhancing drugs? Strongly Agree Strongly Disagree A. E. C. B. D.

© 2010 Pearson Education, Inc. Biology and Society Olympic track and field records appear to have leveled off and perhaps even declined from the early to mid 1990s. Some have suggested that many of the records set during this time period were due to drug-based enhancement. Should these records be expunged? Strongly Agree Strongly Disagree A. E. C. B. D.

© 2010 Pearson Education, Inc. Biology and Society Personal responsibility is a vital component of a free society. Some feel that use of drugs such as anabolic steroids should be a matter of personal choice. Others disagree. Are regulations controlling the use of anabolic steroids properly applied? Strongly Agree Strongly Disagree A. E. C. B. D.