Lesson Plans

Biology 5th Edition ©1999

by Campbell, Reece, Mitchell

Week 10: Transcription, Translation, and the Genetics of Microbes

Chapter 17: From Gene to Protein
Chapter 18: Microbial Models: The Genetics of Viruses and Bacteria

College Board Performance Objectives:

• Explain how the structures of nucleic acids relate to their functions of protein synthesis.
• Describe transcription and translation and relate each to possible mutations.
• Explain the structure and function of viruses.
• Explain the major steps in viral reproduction.
• Explain how viruses transfer genetic material between cells
• Describe the structure and function of the lac operon.

College Board Lab Objectives:

• Explain the principles of bacterial transformation and conditions under which cells can be transformed.
• Explain how a plasmid can be engineered to include a piece of foreign DNA.
• Explain how plasmid vectors are used to transfer genes.
• Explain how antibiotic resistance is transferred between cells.
• Explain how restriction endonucleases function.
• Explain the importance of restriction enzymes to genetic engineering experiments.
• Explain the use of plasmids as vectors to transform bacteria with a gene for antibiotic resistance in a controlled experiment.
• Demonstrate how restrictions enzymes are used in genetic engineering.
• Describe the biological process of transformation in bacteria.
• Calculate transformation efficiency.
• Use multiple experimental controls.
• Design a procedure to select positively for antibiotic resistant transformed cells.

Suggested Laboratory Experiments:

Resources:

• Chapter 17: From Gene to Protein, pp. 294–318
• Chapter 18: Microbial Models: The Genetics of Viruses and Bacteria, pp. 319–343
• Instructor's Guide, pp. 231–277
• Student Study Guide, pp. 118–136
• Test Bank, pp. 195–223
• Lab Manual: none
• CD-ROM: Chapters 17 and 18 include narrated presentations, activities, and links to the Internet.

Pacing Guide:

• Chapter 17: From Gene to Protein—1.5 days
  The focus is DNARNAProtein SynthesisPhenotype The following eatable nucleic acid stud kit will help students understand replication, transcription, and translation. Use a handful of FruitLoops^TM (at least 12 to 15 of each of the five colors) that represent nucleotides, a handful of mixed "lettered" cereal such as Alphabits^TM (amino acids), four square crackers (sugar molecules), and four thin pretzels (covalent bonds). Assign the following FruitLoops^TM colors to represent the designated nitrogenous bases: yellow-thymine, green-adenine, red-cytosine, guanine-blue, and purple-uracil (uracil substitutes for thymine in RNA). First construct a DNA molecule two nucleotides long using the crackers for the deoxyriobose, FruitLoops^TM for nitrogenous bases, and pretzels for covalent bonds. Be sure to use pretzels to indicate the 3' end. Now, make a DNA molecule that is 12 nucleotides long. Emphasize that it is the sequence of the nitrogenous bases that allows for the the code of the traits. Now, using only the nucleotides, do the following.
  1. Unzip it and replicate the DNA.
  2. Unzip and do transcription.
  3. With the RNA from transcription do translation using the Alphabits^TM cereal. Make a key to designate the amino acid that each letter represents.
  4. Use the FruitLoops^TM to make a t-RNA. The goal is have the complementary nitrogenous bases pair so that it forms a hairpin shape.
• Chapter 18: Microbial Models: The Genetics of Viruses and Bacteria—1 day
  1. Construct various virus models. Gather a pile of shoes and use Figure 18.2 a. as a guide to construct a model of the capsid of TMV. Use shoes as the capsomeres, because the shape of capsomeres resemble shoes. Construct an adenovirus by assembling 12 equilateral triangles of light cardboard with a shoestring inside for the nucleic acids. The phage can be made from a nut (tail), bolt (head), and wire (tail fibers). After constructing the models in groups, have a discussion about the various viruses.
  2. Have students perform the lac operon play. For the repressor molecule, lactose, use two people for each molecule since it is a disaccharide, and use a rope for the DNA molecule with sites marked for promoter and operator. The repressor goes up to the rope, grabs it , and kinks it at the operator so that the RNA polymerase (another person) is unable to walk along running his hand on the rope. Then in comes the lactose, grabs the repressor and holds his arms so he is unable to kink the rope. The polymerase detaches. If lactose is absent then get the polymerase to carry a coil of rope and pay it out as he goes along the DNA strand. The second rope is mRNA. Then when the mRNA is made, the beta galactosidase molecules come out to break the lactose molecules in two. They can no longer hold the arms of the repressor once they are cleaved, so he can then go back and kink the DNA rope. This same play would work for the trp operon, only this time the repressor normally has his hands tied until tryptophan comes along and undoes the hands. Then the repressor can go kink that rope.
• Transformation Laboratory, AP* Laboratory 6–Colony Transformation adapted to p-glo plasmid—2.5 days
  This laboratory is similar to the Biology AP* laboratory, and is available from Bio-Rad. It is an excellent guided inquiry lab that uses the p-glo plasmid, and achieves all the AP* objectives. It is also possible to take the green fluorescent protein that is produced and purify it by using gel chromatography. This lab clearly shows the process of DNARNAProtein.
• A skit for colony transformation is helpful as a pre-lab activity. One student holds a 2 liter bottle that is a model of E.coli. Then a circular piece of paper, plasmid from the outside, penetrates the E. coli when it is heated in calcium chloride. Have students take the roles of heat and calcium chloride by placing name tags on them. Use scissors to represent the endonuclease that cuts the DNA and tape as ligase that seals the new DNA into the plasmid. You can have a student play an entrepreneur attempting to make money from making plasmids. Show the p-glo plasmid that results. The same skit can be repeated with the insulin gene and other applications.
• Block Scheduling
  One block on From Gene to Protein, half a block on Microbial Models: The Genetics of Viruses and Bacteria , and one and one half blocks on the colony transformation lab will be just enough time to complete the assignments if the students have read the material and answered questions prior to class.

Key Words:

Suggested Exercises:
Critical thinking questions and end-of-chapter activities are included in these exercises.

1. Challenge Questions, pp. 317–318 #1–3, p. 129 #1–2, and pp. 342–342 #1–3
2. Science, Technology, and Society, p. 318 #1– 2 and p. 343 #1–2

Troubleshooting Tips/Error Traps: