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Life Science

  • Bacterial Hydrolysis of Starch In this lab, students culture two bacteria on potato dextrose agar, which contains starch. When grown on potato dextrose agar, bacteria that can secrete amylase—an enzyme that hydrolyzes starch—create a zone around their colonies in which starch is absent. When the agar is flooded with iodine solution, most of the plate stains dark blue–black, but clear areas are left around colonies that secrete amylase. View »
  • Bacterial Motility In this lab, students perform two exercises that investigate microbial motility. One is on a microscopic level, using the “hanging drop” slide preparation method to directly observe motile cells. The second exercise is on a macroscopic level and involves inoculating motility test media. View »
  • Having Friends Over for Lunch: The Mutualism of Paramecium bursaria and Endosymbiotic Algae When you teach symbiosis and endosymbiotic theory, consider using Paramecium bursaria, a protist that forms a mutualistic relationship with algae. View »
  • Bacteria: The Indole Test In this lab students perform a differential test to distinguish bacteria based on the production of indole. Bacteria are grown on media containing tryptophan and then treated with Kovac’s reagent. If they possess the enzyme tryptophanase, the bacteria can metabolize tryptophan into indole, pyruvic acid, and ammonia. View »
  • Bees at School Bradley James, co-owner of Beepods, explains the benefits of keeping bees at school. Learn about the buzz, and why bees are the perfect organism to engage students and promote hands-on learning. View »
  • Introduction to Prokaryotes: Bacteria What are bacteria? In this introductory lab students make smears of bacteria on microscope slides from pure cultures, perform a simple stain, and observe their stained slides under a microscope View »
  • Bacterial Growth on MacConkey Agar In this lab students culture three bacteria on nutrient agar and MacConkey agar and record the results. View »
  • Introduction to Prokaryotes: Archaea In this lab, students are introduced to Halobacterium, a representative of the Archaea, one of the three domains of life (along with Bacteria and Eukarya). View »
  • Snakeheads Invade the United States Teach your students about the challenges nonnative species pose by focusing on a current example, the northern snakehead fish. Native to China, Russia, and Korea, this fish has established breeding populations in several states. Find out how this might have happened and what scientists are doing about it. View »
  • Bacterial Hydrolysis of Casein In this lab, students culture two bacteria on skim milk agar. The protein casein gives milk its white color. Some bacteria secrete protease enzymes that can hydrolyze casein. When these bacteria are grown on skim milk agar a clear area develops around the colonies, indicating that casein has been hydrolyzed into its component amino acids. View »
  • Bacterial Hydrolysis of Lipids In this lab, students culture two species of bacteria on agar medium that contains an emulsion of plant oils and the dye, sprit blue, which forms a complex with the triglycerides of the oils and gives an opaque blue color to the agar. Colonies of bacteria that can secrete lipase, an enzyme that hydrolyzes triglycerides, develop a light area or “halo” in the surrounding medium, due to the diffusion of lipase into the medium and the resultant breakdown of the oil/spirit blue complex. View »
  • Isolating Bacteria from a Mixture How does a microbiologist isolate bacteria from a sample? In this lab students practice streaking a plate to isolate a single species of bacterium from a known mixture. View »
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