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 ChallengeOur group: Cell/Developmental BiologyTarget: introductory biology course, majors or non-majors, of any sizeThe 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 analogySpecific objectives are in our course description document

Learning Goals/ObjectivesAfter 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 classPreliminary 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

SummaryCar is organized

partssubsystems systemsconnections

Organization is important to functionCar has processes

simultaneousconnections

Processes important to functionProcesses 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 analogyNow use the same procedure as with the car, but with the human body

list functions body must perform to livelist body partscategorize body parts according to functionparts must be assembled in correct locationscertain activities must occur for body to functionmay or may not include formative assessment by performing “perturb and predict” exercises

Concept MapsNOTE: 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 cellPresent 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)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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

nucleusendoplasmic reticulum ribosomes mitochondriacytosolsynthesis 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

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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 IdeaLiving Things Are Organized.

Spatially- certain parts are located in certain placesTemporally - certain processes take place in a certain orderFunction is dependent on both spatial and temporal organizationInterconnectedInteractionsHierarchical (systems, subsystems, sub-subsystems . . .)

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

MetabolismMitosisProtein synthesisIntracellular signalingIntercellular 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 outCar 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)