Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Active Lecture Questions for use with Classroom Response Systems Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Mitchell, and Taylor Essential Biology, Second Edition – Campbell, Reece, and Simon Questions prepared by Brad Williamson Chapter 3 The Molecules of Cells

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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? 1)Mostly hydrophobic R-groups are on the surface of the molecule. 2)Mostly hydrophilic R-groups are on the surface of the molecule. 3)The R-groups on exterior of the molecule are mostly non-polar. 4)The R-groups on the exterior are constantly changing between non-polar and polar as the protein chain bends and folds.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Answer 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? 2)Mostly hydrophilic R-groups are on the surface of the molecule.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept Check When proteins are heated, they usually denature. If moderate heat was applied to this molecule of DNA what part of the molecule would break down or break apart first? (Use your knowledge of chemical bonds.) 1)The nucleotides along each side would break apart. 2)The sugar-phosphate backbone would separate from the nitrogen bases. 3)The nitrogen base pairs would separate in the interior of the molecule.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Answer When proteins are heated, they usually denature. If moderate heat was applied to this molecule of DNA what part of the molecule would break down or break apart first? (Use your knowledge of chemical bonds.) 3)The nitrogen base pairs would separate in the interior of the molecule.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interpreting Data It is the amino acid “R” groups that interact to create the three dimensional structures of proteins. Some amino acids have hydrophilic side groups some have hydrophobic side groups. In the hydrophilic group some “R” groups are acids and others are bases: Acid “R” groups end with a carboxyl group. Basic “R” groups end with amine group.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 +

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interpreting Data This a graph that 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 carry a charge? 1)Aspartic acid 2)Glutamic acid 3)Lysine 4)All of the above

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Answer This a graph that 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 carry a charge? 4)All of the above

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interpreting Data At an acidic pH of 3 which of the following amino acids carry a charge? 1)Aspartic acid 2)Glutamic acid 3)Lysine 4)All of the above

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Answer At an acidic pH of 3 which of the following amino acids carry a charge? 3)Lysine

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interpreting Data At a basic pH of 12 which of the following amino acids carry a charge? 1)Aspartic acid 2)Glutamic acid 3)Lysine 4)1. and 2.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Answer At a basic pH of 12 which of the following amino acids carry a charge? 4)1. and 2.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Science 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 played a large role in the 2005 summer Olympics. Do you agree that organizations like the IOC should ban the use of performance enhancing drugs? Strongly Agree Strongly Disagree

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Science and Society Olympic track and field records appear to have leveled off and perhaps even declined from the early to mid 1990’s. 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

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Science 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 regulating the use of anabolic steroids properly applied? Strongly Agree Strongly Disagree

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings You Decide Low-carb diets are the best way to lose weight. Strongly Agree Strongly Disagree Low-fat or low-carb diets - which is healthier?