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Life Science

  • 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 Growth on MacConkey Agar In this lab students culture three bacteria on nutrient agar and MacConkey agar and record the results. 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 »
  • 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 »
  • The Science of Fear You know that hair-raising feeling you get when you’re scared? By undergoing a specific physiological response, your body is primed to confront, and hopefully overcome, whatever scary situation you face. View »
  • Living Organism Care Guide: Caenorhabditis elegans Get care instructions for Caenorhabditis elegans, including details on housing and feeding, information about the organism, related resources, and FAQs. 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 »
  • Introduction to Prokaryotes: Cyanobacteria In this lab students observe two examples of cyanobacteria and make a simple comparison to a eukaryotic green alga. View »
  • 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 »
  • Introduction to Sterile Technique In this lab, students practice transfer of a bacterial culture using sterile technique. 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 »
  • Dissections in a Flipped Mastery Classroom Dissection plays an essential role in every anatomy and physiology class. As a teacher, you know it’s valuable, but do your students? Show them the value of performing dissections and give them a learning experience that’s authentic and engaging when you use the flipped-mastery approach. View »
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