Exocytosis and secretion

The exocytosis and secretion lab deals with the induction of stimulus-dependent secretion, a topic well studied in Tetrahymena. This lab can also be linked to evolution of defense mechanisms in lower eukaryotes. Students induce secretion of a gelatinous capsule around the whole cell (visually similar to the jelly capsule surrounding frog eggs) in response to Alcian Blue. Cell reaction is captured by microscope mounted digital cameras using real time and time lapse exposures. Survival of the cells and ability to secrete a second capsule in response to stimulation are explored. Classroom modifications include examining the role various stimulants and calcium concentration in the secretory process. Students are encouraged to formulate their own questions and design experiments to answer them, e.g. what effect does media or temperature or cell density have on secretory behavior.

Capsule formation

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Module Protocols
High School

Glossary of Terms

Relevant Concepts

Subcellular organization; Defense Mechanisms; Relationship of Structure to Function; Science as a Process; Interorganismal Relationships; Survival Mechanisms

Next Generation Science Standards Relationships

High School:  |

Middle School: |

NYS Science Curriculum Guideline Relationships

Key Ideas | | | |


Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.
Conduct an investigation to provide evidence that living things are made of cells, either one cell or many different numbers and types of cells.
Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.
The central purpose of scientific inquiry is to develop explanations of natural phenomena in a continuing and creative process.
Beyond the use of reasoning and consensus, scientific inquiry involves the testing of proposed explanations.
The observations made while testing proposed explanations, when analyzed using conventional and invented methods, provide new insights into natural phenomena.
Organisms maintain a dynamic equilibrium that sustains life.
Plants and animals depend on each other and their physical environment.