Eukaryotic Cell Organization: Breaking the Jell-O Salad Mold Stephanie Aamodt, LSU-Shreveport Beverly Clendening, Hofstra Univ. Hans Landel, Edmonds Community College Doug Luckie, MSU John Rebers, Northern Michigan University
Description of the Challenge Our group: Cell/Developmental Biology Target: introductory biology course, majors or nonmajors, of any size The Misunderstanding: the eukaryotic cell is a collection of individual and isolated parts, randomly arranged in the cell The Jell-O Salad paradigm You will see later what we want students to think instead the Jell-O Salad model (what our objectives are) because we do not want to prejudice you, but we can tell you: Emphasis on model-based reasoning, relying on analogy Specific objectives are in our course description document
Learning Goals/Objectives After completing this unit the student will: Be able to describe cellular organization and the way this organization relates to function Be able to relate the organization of the cell to different functional activities Be able to make reasonable assumptions about the reasons for differences between prokaryotic and eukaryotic cells At the end of the course, the student will: Be able to apply the idea that function is dependent on organized structure to the organization of living things, including the following levels: o Chemical/molecular o Cellular/organelle o Tissue/organ/system o Organisms/ecosystems
Preliminaries Before this class Preliminary introduction to macromolecules Class discussion: Define living things and generate list of requirements Introduce cells as the smallest unit of life All cells have membrane, DNA, cytoplasm
The class part Run through first part of class
Summary Car is organized parts subsystems systems connections Organization is important to function Car has processes simultaneous connections Processes important to function Processes and Organization are interdependent
The FIRST part Describe rest of class
TRANSITION: Bring the Class to Biology have been examining a non-living object let s use what we have learned about the car to examine a living object -- the human body
TRANSITION: Bring the Class to Biology The procedures with the car has served as a model for what we would like the students to do. Car will serve as an analogy Now use the same procedure as with the car, but with the human body list functions body must perform to live list body parts categorize body parts according to function parts must be assembled in correct locations certain activities must occur for body to function may or may not include formative assessment by performing perturb and predict exercises
Concept Maps NOTE: Homework (assessment) will include concept mapping of cell parts with respect to function If students have not been introduced to concept maps, a good place to introduce them is at the point when they are asked to categorize the parts of the body according to function. This will model for them what we would like them to do in the homework assignment.
Possible example concept map: plants
Example of a poor concept map Sentence-in-a-box Poor concept map Good concept map should show complex relationships One part can have multiple relationships Use linking terms to show how parts are related Focus on most important connections
FOCUS: Bring the class to the cell level Important transition Have established a context for describing and understanding the cell
Break the Jell-O salad mold More than a boring parts list Structures are not isolated; they are interconnected Structures are not randomly placed; they are highly organized The organization is not static; it is dynamic
Repeat steps 1 through 3 Ask the class to list functions cell must perform to live, and the parts of the cell Can the students group the parts according to function? Can the students organize the parts of the cell? Make connections?
Recognize that student knowledge is limited Students will have some prior knowledge, but it will be simple, pat definitions. Allow class to explicitly identify what they don t know or understand. Emphasize that what we don t know as a class will direct the rest of the unit.
Model a dynamic view of the cell Present an exciting mini-lecture on one cell structure or organelle as an example for the class. Include a video clip of a cell process such as mitosis or transport or a cell in motion. Describe how the structure is made of smaller parts that fit together precisely to allow a specific, controlled process (Here, model means showing students what we expect them to do)
Encourage students to think The contextual framework will be reinforced by homework and assessments. The dynamic, highly organized view of life will be further developed in classes on cellular respiration, mitosis and most other topics, as well, as the course continues into the study of cell biology.
Assignment 1. Complete the structure/function chart for the cell that was begun in class. The information can be found in Chapter x of your textbook. this forces the students to learn the parts on their own, but within the context of function
2. Draw a concept map that shows the spatial and functional relationships among nucleus endoplasmic reticulum ribosomes mitochondria cytosol synthesis of macromolecules (anabolic metabolism) breakdown of macromolecules for energy production (catabolic metabolism) Examples of connecting phrases (is connected to, takes place in, etc.) this assesses their understanding of the concepts of spatial and temporal organization
3. Label the cell compartments with their functions.
4. Predict, in detail, what would happen if Group A there was a hole in the cell membrane. the cell had no mitochondria. a mature cell lost its nucleus. Group B none of the ribosomes were attached to the endoplasmic reticulum. the process of vesicle formation could not occur (the Golgi apparatus could not form vesicles). Pick one from Group A and one from Group B this assesses their understanding of the importance of spatial and temporal organization of cells
The EXCITING significance of this unit It covers a BIG idea in Biology It is scalable for use in other topics
The Big Idea Living Things Are Organized. Spatially- certain parts are located in certain places Temporally - certain processes take place in a certain order Function is dependent on both spatial and temporal organization Interconnected Interactions Hierarchical (systems, subsystems, subsubsystems...)
Permeation of the Big Idea you can (and we think you should) re-examine the importance of spatial and temporal organization when the following cellular topics are discussed Metabolism Mitosis Protein synthesis Intracellular signaling Intercellular signaling our assessments can be used after any of these topics, and in midterm and final exams
Active Transport of the Big Idea The Big Idea applies (by definition) to all levels of biology. We think it should be continually stressed. Macromolecules Organelles Tissues Organs Organisms Communities Ecosystems
Scalability of Exercise Because life is hierarchically organized, with each level exhibiting spatial and temporal organization (i.e., because it is a Big Idea), this exercise can be used at any level. (it has wide applicability)
Living things are organized. Replace Living Things with... Macromolecules Organelles Tissues Organs Organisms Communities Ecosystems
Revisions? Feedback from FIRST participants suggests Transition (human body) step can be left out Car analogy has sexual bias -- women will have a harder time relating to it we had discussed this and had decided to address this by calling on women first also, you can use ANY object you would like as your analogy, as long as it it sufficiently complex, has processes, and is understandable by the majority of your students (see course description document)