Cell Structure and Function – Major Concepts and Learning Activities
Dr. Ingrid Waldron, Department of Biology, University of Pennsylvania, © 20141
These Teacher Notes supplement a typical textbook description of the cell and its components.
The key concepts and suggested activities provided below are designed to engage students in
active learning and to overcome some common student misconceptions and confusions.
Students often think of a cell as a static structure consisting of multiple independent parts.
Students often do not understand how the parts of the cell work together to accomplish the
multiple functions of a dynamic living cell. Students also often confuse different levels of
organization such as molecules, organelles and cells.
To overcome these limitations in student understanding, key concepts and learning activities are
presented in three sections:
 Molecules, Organelles and the Dynamic Functioning of Eukaryotic Cells
 How Substances Move Into and Out of Cells and Within Cells
 Diversity of Cell Structure and Function
Many of the activities are designed for students who already have a basic understanding of the
functions of cell organelles and biological molecules. Some of the recommended activities are
explicitly aligned with the Next Generation Science Standards (as indicated by (NGSS) in the
description and explained in the Teacher Notes for these activities on the Serendip website).
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I. Molecules, Organelles and the Dynamic Functioning of Eukaryotic Cells
Key Concepts
 Inside a living cell there is constant activity.
 A cell has many parts that work together to accomplish the functions of life.
 Each part of a cell consists of many molecules that cooperate to accomplish needed
functions. In eukaryotic cells, many of these molecules are organized in tiny organelles
that perform specialized functions inside the cell.
Learning Activities
A. Video and animations provide an excellent way to give students an intuitive feel for the
dynamic nature of living cells. Two of the best for this purpose are:
Neutrophil (a phagocytic cell) Chasing a Bacterium – a video of two cells in motion,
available at http://www.biochemweb.org/neutrophil.shtml
A eukaryotic phagocytic cell uses chemical information to pursue and then eat a bacterium.
Students see the dynamic changes in shape as the neutrophil moves as well as the extreme
difference in size between eukaryotic and prokaryotic cells.
For an excellent dynamic animation showing how different parts of the cell cooperate, see
http://multimedia.mcb.harvard.edu/anim_innerlife_hi.html
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These Teacher Notes and multiple activities for teaching biology are available at http://serendip.brynmawr.edu/exchange/bioactivities. Handson, minds-on activities for teaching biology are available at http://serendip.brynmawr.edu/sci_edu/waldron/.
I suggest showing only part of this animation, beginning about halfway through with
microtubules and transport vesicles or a little bit later with pores in the nuclear membrane that
allow mRNA to leave the nucleus, and continuing through exocytosis of secreted proteins and
membrane proteins (excellent approximately three-minute segment). You probably will want to
turn off the narration (which is very detailed) and give a student-friendly narration. You may
want to use the relevant section from http://sparkleberrysprings.com/innerlifeofcell.html to
develop your script. You may also find it helpful to view the version with labels available at
http://biogeonerd.blogspot.com/search?q=leukocyte ; in this version the animation of motor
proteins carrying vesicles is shown beginning at about 3 minutes and 40 seconds.
B. Analysis and Discussion Activities
Cells as Molecular Factories, available at
http://serendip.brynmawr.edu/exchange/bioactivities/cellmolecular
The questions in this analysis and discussion activity prompt students to think about how the
different parts of a eukaryotic cell cooperate to function as a protein-producing factory and as a
recycling plant. Additional questions require students to identify the locations and functions of
different types of molecules in eukaryotic cell organelles.
Structure and Function of Molecules and Cells, available at
http://serendip.brynmawr.edu/exchange/bioactivities/SFMolecCell
In this analysis and discussion activity, students learn how the function of molecules and cells is
related to their structure (including shape, constituent components, and relationships between
components). Students analyze multiple examples of the relationship between structure and
function in diverse proteins and eukaryotic cells. In addition, students learn that cells are
dynamic structures with constant activity, students learn about emergent properties, and students
engage in argument from evidence to evaluate three alternative claims concerning the
relationship between structure and function. (NGSS)
C. Card Sort Activity – From Coffee to Carbon available at
http://teach.genetics.utah.edu/content/begin/cells/print/CoffeetoCarbon.pdf
This activity has students sort cards, each with a molecule, organelle or sell, according to size.
To use this activity to reinforce student understanding of different levels of organization, I
recommend that you begin by having your students sort the cards into four categories: molecules,
organelles, cells, and other. After you have discussed this initial card sort into categories, then
have your students organize the cards from smallest to largest. (Depending on your students, you
may want to omit some cards such as adenine, influenza virus, baker's yeast.) After students
have completed the card sort by size, discuss the results and show the animation which illustrates
the relative sizes (available at http://learn.genetics.utah.edu/content/begin/cells/scale/). The
order of magnitude differences in size can be used to help students realize that eukaryotic cells
are made up of many many organelles and each organelle is made up of many many molecules.
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II. How Substances Move Into and Out of Cells and Within Cells
Key Concepts:
 Diffusion plays a very important role in moving substances into and out of cells and
moving substances around inside of cells. However, diffusion has important limitations.
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Diffusion is relatively rapid over very short distances, but extremely slow over longer
distances.
The rate of diffusion into and out of a cell is proportional to the surface area of the
plasma membrane. In contrast, the rate that a cell uses substances such as O2 is
proportional to cell volume. Therefore, diffusion can only supply adequate amounts of
O2, nutrients, etc. if the surface-area-to-volume ratio is large enough.
As cell size increases, the rate of diffusion from the plasma membrane to the center
decreases and the surface-area-to-volume ratio decreases. This is a very important reason
why most cells are tiny.
Another limitation of diffusion is that diffusion is very slow for large molecules. Also,
diffusion only moves substances from regions of higher concentration to regions of lower
concentration. To overcome these limitations of diffusion, cells use a variety of energyrequiring processes to pump substances into or out of the cell and to move substances
within the cell.
Learning Activities
A. Hands-On Activities
Introduction to Osmosis, available at http://serendip.brynmawr.edu/sci_edu/waldron/#osmosis
This activity begins with a student investigation of the phenomenon of osmosis and then moves
to analysis of the mechanism and implications of osmosis. In Part I, "What is happening to these
eggs?" students observe and analyze the effects of osmosis on eggs. In Part II, "Understanding
Osmosis", analysis and discussion questions introduce students to the molecular basis for
osmosis and challenge students to apply their understanding of osmosis to several real-world
phenomena. (NGSS)
Diffusion Across a Selectively Permeable Membrane, available at
http://serendip.brynmawr.edu/sci_edu/waldron/#diffusion
Students investigate the effects of molecule size on diffusion across a synthetic selectively
permeable membrane. This investigation includes observation and analysis of osmosis (diffusion
of water across a selectively permeable membrane). Additional questions guide students in
analyzing the relative advantages of two different models of the cell membrane. (NGSS)
B. Analysis and Discussion Activity
Diffusion and Cell Size and Shape, available at
http://serendip.brynmawr.edu/exchange/bioactivities/celldiffusion
This analysis and discussion activity helps students understand that cell size is limited by the
very slow rate of diffusion over any substantial distance and the insufficient surface-area-tovolume ratio for larger cells. In addition, students calculate why these problems do not apply to
long slender cells or parts of cells such as the axons of neurons.
C. Web-based Animations and Videos of Energy-Requiring Processes that Cells Use to Move
Substances
Cell membranes contain protein molecular pumps which move substances from areas of low
concentration to areas of high concentration (opposite from the direction of net flow due to
diffusion). Animations are available at:
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http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pu
mp_works.html
Within eukaryotic cells, large molecules such as proteins are often moved in transport vesicles
carried by motor proteins along microtubules. This can be observed in the excellent animation
available at http://multimedia.mcb.harvard.edu/anim_innerlife_hi.html
I suggest showing only part of this animation, beginning about halfway through with
microtubules and transport vesicles or a little bit later with pores in the nuclear membrane that
allow mRNA to leave the nucleus, and continuing through exocytosis of secreted proteins and
membrane proteins (excellent approximately three-minute segment). You probably will want to
turn off the narration (which is very detailed) and give a student-friendly narration. You may
want to use the relevant section from http://sparkleberrysprings.com/innerlifeofcell.html to
develop your script. You may also find it helpful to view the version with labels available at
http://biogeonerd.blogspot.com/search?q=leukocyte ; in this version the animation of motor
proteins carrying vesicles is shown beginning at about 3 minutes and 40 seconds.
Large eukaryotic cells also use cytoplasmic streaming e.g. in the pseudopods of amoebae and to
move the food vacuole of paramecia, as shown in the animation at http://highered.mcgrawhill.com/sites/9834092339/student_view0/chapter4/animation_-_cytoplasmic_streaming.html
Time-lapse video of cytoplasmic streaming is available at
http://web.bf.uni-lj.si/bi/botanika/aleskl/timelapse/elodea-kloroplasti-1.mov
http://www.youtube.com/watch?v=6hJ_i_-K--k
http://www.youtube.com/watch?v=PFtzs_cUddI&feature=related
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III. Diversity of Cell Structure and Function
Key Concepts
 Different types of eukaryotic cells have different shapes and different amounts of specific
types of organelles, corresponding to their different functions in different parts of an
organism or in different eukaryotic organisms (e.g. animals vs. plants).
 Eukaryotic and prokaryotic cells differ substantially in size and internal structure, but
eukaryotic and prokaryotic cells share some important similarities (plasma membrane,
ribosomes, and many identical or similar molecules) and both types of cells carry out the
activities of life.
Learning Activities
Analysis and Discussion activities
Structure and Function of Molecules and Cells, available at
http://serendip.brynmawr.edu/exchange/bioactivities/SFMolecCell
In this analysis and discussion activity, students learn how the function of molecules and cells is
related to their structure (including shape, constituent components, and relationships between
components). Students analyze multiple examples of the relationship between structure and
function in diverse proteins and eukaryotic cells. In addition, students learn that cells are
dynamic structures with constant activity, students learn about emergent properties, and students
engage in argument from evidence to evaluate three alternative claims concerning the
relationship between structure and function. (NGSS)
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Structure and Function of Cells, Organs and Organ Systems, available at
http://serendip.brynmawr.edu/exchange/bioactivities/SFCellOrgan
In this analysis and discussion activity, students learn how the structure of cells, organs and
organ systems is related to their functions. (Structure includes shape, constituent components,
and relationships between components.) Students analyze multiple examples of the relationship
between structure and function in diverse eukaryotic cells and in the digestive system. In
addition, students learn that cells are dynamic structures with constant activity and they learn
how body systems interact to accomplish important functions. (NGSS)
Prokaryotic vs. Eukaryotic Cells, available at
http://mrobiology2012.pbworks.com/w/file/fetch/47637831/prokar
This worksheet provides students with information about the similarities and differences between
prokaryotic and eukaryotic cells and asks them to create a detailed Venn diagram comparing and
contrasting these two types of cells. You may want to supplement this with the concept map on
the next page of these Teacher Notes.
Hands-on Activity
Using a Microscope to See Different Types of Cells, available on the cell biology page at
https://sites.google.com/site/biologypd/home
In this activity students learn about diversity of cell structure and function by examining human
red blood cells and white blood cells, frog red blood cells, cheek cells, bacteria, and different
Protista.
IV. Additional Resources for Teaching about Cells
A. Source Materials and Animation
Inside the Cell – chapters 1 and 2 provide a very informative overview of the cell, available at
http://publications.nigms.nih.gov/insidethecell/
Inside a Cell – animation available at
http://learn.genetics.utah.edu/content/begin/cells/insideacell/
B. Review Activities
Cell Vocabulary Review Game, available at
http://serendip.brynmawr.edu/exchange/bioactivities/cellvocab
Crossword puzzles on cell structure available at http://www.cellsalive.com/puzzles/index.htm
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Place the following words or phrases into the concept map:
activities of life, all organisms, animals, bacteria, cells, eukaryote, fungi,
membrane-bound organelles, nucleus, plants, prokaryote, protists, unicellular, viruses
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