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Introductory Biology

  • Enzymatic avocado browning is driven by polyphenol oxidase. Mashed avocado pulp is bright green but turns dark brown over the course of two hours at room temperature in the presence of air and salt. This reaction can be accelerated or inhibited by more than 20 different testable reagents, allowing students to explore experimental design.

    The Avocado Lab: An Inquiry-Driven Exploration of an Enzymatic Browning Reaction

    Learning Objectives
    Students will be able to:
    • develop a testable research question and supportive hypothesis regarding the browning of damaged avocado flesh caused by the activity of avocado polyphenol oxidase (aPPO).
    • design and execute a well-controlled experiment to test aPPO hypotheses.
    • evaluate qualitative enzyme activity data.
    • create a figure and legend to present qualitative data that tests multiple hypotheses and variables.
    • search for and correctly cite primary literature to support or refute hypotheses.
    • know the role of reducing reagents, pH, chelators, and temperature in reactions catalyzed by aPPO.
    • explain why the effects of salt and detergent differ for aPPO experiments conducted in situ
    • (in mashed avocado flesh) as compared to in vitro (on purified protein).
    • discuss how substrate and cofactor availability affect aPPO reactions.
    • describe how endogenous subcellular organization restricts aPPO reactions in a healthy avocado.
    • evaluate food handling practices for fruits expressing PPO.
  • A three-dimensional model of methionine is superimposed on a phase contrast micrograph of Saccharomyces cerevisiae from a log phase culture.

    Follow the Sulfur: Using Yeast Mutants to Study a Metabolic Pathway

    Learning Objectives
    At the end of this lesson, students will be able to:
    • use spot plating techniques to compare the growth of yeast strains on solid culture media.
    • predict the ability of specific met deletion strains to grow on media containing various sulfur sources.
    • predict how mutations in specific genes will affect the concentrations of metabolites in the pathways involved in methionine biosynthesis.
  • Hydrozoan polyps on a hermit-crab shell (photo by Tiffany Galush)

    A new approach to course-based research using a hermit crab-hydrozoan symbiosis

    Learning Objectives
    Students will be able to:
    • define different types of symbiotic interactions, with specific examples.
    • summarize and critically evaluate contemporary primary literature relevant to ecological symbioses, in particular that between hermit crabs and Hydractinia spp.
    • articulate a question, based on observations of a natural phenomenon (in this example, the hermit crab-Hydractinia interaction).
    • articulate a testable hypothesis, based on their own observations and read of the literature.
    • design appropriate experimental or observational studies to address their hypotheses.
    • collect and interpret data in light of their hypotheses.
    • problem-solve and troubleshoot issues that arise during their experiment.
    • communicate scientific results, both orally and in written form.
  • Summary diagram of the Pipeline CURE. A diagram describing how undergraduates, faculty, and research trainees progress through a sequence of guided research activities that develop student independence.