CELLS
Cells
3.0 LIFE SCIENCE: The students will use the scientific skills and processes to explain the
dynamic nature of living things, their interactions, and the results from the interactions that occur
over time.
B. CELLS
1. Provide evidence from observations and investigations to support the idea that some
organisms consist of a single cell.
a. Use microscopes, other magnifying instruments, or video technology to observe, describe, and
compare single celled organisms, such as amoeba, euglena, paramecium, etc.
b. Describe the observable behaviors of single celled organisms.
c. Cite evidence from data gathered that supports the idea that most single celled organisms
have needs similar to those of multicellular organisms.
Curricular
Connection
2. Investigate and provide evidence that living things are made mostly of cells that can be
seen and studied only through a microscope.
a. Use microscopes and/or other video technology to investigate and describe that some
organisms are composed of a collection of similar cells working together to meet basic needs of a
“colony” of cells.
b. Use microscopes and pictures to investigate, describe with drawings, and compare the cells in
a variety of multicellular organisms, such as cells in elodea and onions; muscle cells, nerve cells,
skin cells, etc in animals.
E. Flow of Matter and Energy
1. Recognize that some source of energy is needed for all organisms to grow and survive.
a. Identify the sun as the primary source of energy for all living organisms.
o
o
Plants use sunlight to make food
Plants and animals use food for energy and growth
What is Cell Theory?
Background
In 1839 two scientists, Theodor Schwann and Matthias Jakob Schleiden, formulated what is called
the cell theory. The cell theory states that all living things are made up of one or more cells. An
organism, which is another word for a living thing, that is made up of one cell is unicellular. An
organism that is made up of more than one cell is multi-cellular.
The cell theory also states that new cells are produced by cells that have already formed.
Additionally, Schwann and Schleiden believed that cells contain the information that is passed on
to new generations of cells. This includes information on heredity that will pass on to the offspring
of the original organism.
The final part of the cell theory states that any function that is vital to life within an organism occurs
in the cells.
Resource: Adapted from Instructor WEB, What is a Cell? http://www.instructorweb.com/lesson/cell.as
What is a Cell?
A cell is the very smallest unit of living matter. Cells are made of atoms, which are the smallest
units of matter. There are many different kinds of cells. The two kinds you are most likely to be
familiar with are animal and plant cells. Some of the differences between them are that plant cells
have a cell wall and chloroplasts, whereas animal cells do not. Cells come in different sizes and
shapes. The nerve cell of the giant squid may be as long as 39 feet! The cells in one organism
may have different shapes, sizes, and jobs. Multicellular organisms such as humans are made up
of trillions of cells such as nerve cells, muscle cells, blood cells, and skin cells to name a few.
There are also one-celled (single-celled) organisms such as the euglena, paramecium, amoeba,
and bacteria. Single-celled organisms have to be able to do all the same life-sustaining activities
that multicellular organisms do, such as take in food and eliminate waste products, grow and
develop, take in oxygen and eliminate carbon dioxide (or vice versa).
Background
(continued)
All cells have some parts in common. One part found in all cells is the cell membrane. The cell
membrane surrounds the cell, holds the other parts of the cell in place, and protects the cell.
Molecules can pass in and out of the cell membrane. Inside the membrane, all cells, except for
bacterial cells, contain a nucleus and cytoplasm. The nucleus is a dark structure located in the
middle of the cell. It is the control center of the cell. Inside the nucleus there is DNA that contains
genetic information. The cytoplasm is a jelly-like substance inside the cell where most of the cell's
activities take place. It's made out of water and other chemicals.
Like all living things, cells die. In just one minute about three billion cells in the human body die. In
that same minute, about three billion cells divide so that all the cells that die are replaced. Dead
skin cells flake off and dead cells from internal organs will pass through and out of the body with
waste products. The length of time cells live can vary. For example, white blood cells only live for
thirteen days, red blood cells live for about one hundred and twenty days, liver cells live about
eighteen months, and nerve cells can live up to one hundred years.
Each cell is made from an existing cell. New cells are made through a process called cell division
or mitosis. One cell turns into two cells and then two cells turn into four cells, etc. Multicelluar
organisms, including humans, begin life as a single cell. Most of the cells in multicellular organisms
use a process called mitosis to reproduce and make new cells. Many single-celled organisms use
a process similar to mitosis called binary fission to reproduce exact copies of themselves.
Resource: Adapted from Oracle ThinkQuest, Excel at Cells http://library.thinkquest.org/5420/cellwhat.html
What is a Compound Light Microscope?
Background
(continued)
One of the most important tools that scientists use to study cells is the compound light microscope.
Most compound light microscopes are capable of magnifying a cell up to one thousand times its
normal size. But even with large magnifications, the very detailed parts of some cells can't be
seen. A compound light microscope has an ocular lens or eyepiece that has a magnification of 10x
(ten times the normal size of the object being viewed). There are also three objective lenses, with
magnifications of 10X, 40X, and 100X. The magnification of the ocular lens is multiplied by the
magnification of the objective lens to obtain the final magnification of the object. In other words,
viewing an object through the ocular lens and the 10X objective lens results in a total magnification
of 100X.
Resource: Adapted from Microbiology Suite 101, What is a Compound Light Microscope? http://www.suite101.com/content/what-is-acompound-light-microscope-a68284
Teacher Materials
Materials/
Resources
Safety
digital microscope connected to a laptop
which is linked to a large LCD television
screen
glass depression microscope slides
cover slips
dropper
pond water culture
Student Materials
(1of each item per student)
compound light microscopes
plastic depression viewing slides
dropper
field microscope with viewing
chamber, plastic syringe, plastic
forceps and carrying case
specimen collection container
large collection syringe (turkey
baster)
Students are to use caution around water areas.
Students should not wade into the water. Students should remain on the shore at all
times.
No more than 4 students at a time should be on the Turtle Pond dock.
Students are not to walk on logs that have fallen into the water.
All samples are to be collected using the extension poles with collection cups or the large
syringes.
Students should not handle living things, plants or animals, unless directed to do so by a
Fairview Resource Teacher.
Everyone should wash their hands thoroughly with soap and water at the end of the
lesson.
Enduring
Questions and
Focus
Questions
Enduring Questions
What is an ecosystem and how does it support life?
What are the biotic (living) and abiotic (nonliving) components of an ecosystem and how
do they interact?
Focus Questions
How would you describe and compare single celled and multicellular organisms found in
an aquatic ecosystem?
What are the roles and behaviors of single celled and multicellular organisms in aquatic
ecosystems?
cell – the smallest unit of life capable of carrying on life’s functions
producer – an organism that makes its own food
consumer – an organism that eats other organisms for food
protist – a diverse group of microorganisms containing a nucleus that live in almost any
environment that has liquid water
Vocabulary
biotic – with life (living things such as plants and animals)
abiotic – without life (non-living things such as rocks, water, etc.)
ecosystem – a complex set of relationships between living organisms and their environment
environment – the physical surroundings of an organism which includes the living (biotic) and
nonliving (abiotic) components
unicellular or single celled– organisms composed of only one cell
multicellular – an organism that is composed of many cells
organism – a living thing
photosynthesis – a chemical process that occurs in plants, algae, and some bacteria, that uses
carbon dioxide, water and the energy of sunlight to produce oxygen and sugar
5 E Model
Time
Frame
10 minutes
Activity
Slides 1: Cell Detectives
Refer the students to the opening slide. Ask them what they think it means to be
a cell detective. Lead them to discover that detectives are observant and look
closely for evidence that something is there. Tell them that they will not be able
to see the cells they are looking for with just their eyes, but that they will need to
use equipment that magnifies things and makes them larger.
Engage
Show the students the two cell models: plant and animal. Discuss similarities
and differences. Ask: What do plant cells have that animal cells lack? Discuss
the fact that plant cells have chloroplasts and cell walls and animal cells do not.
Explain to students that cells are the smallest form of living matter and that
everything occurs on a cellular level. For example, talking only happens
because all the nerve cells, brain cells and muscle cells are working together!
Ask: What is the difference between multi-celled and single-celled organisms?
Discuss. Include in the discussion that plants and animals are multicellular
organisms and most protists are single-celled or unicellular organisms. Tell
students that they are going to be looking at several different kinds of singlecelled organisms called protists, as well as several microscopic animal
organisms.
Show the students the “mystery soup” in the mini-pond culture.
(The mini-pond is a culture of pond water and nutrients in a clear plastic
container that is teeming with different kinds of protists.)
Ask: What do you see? Discuss.
Ask: What do you think lives in the mystery soup? Discuss.
Say: This might not be a place where you and I want to live but it is a perfect
environment for some living things, even if it is an ooey-gooey greasy-grimy
slippery-slimy stinky place!
Do not tell the students what is in the “pond” at this time. If they guess answer
with, “We’ll see!”
Slide 2: What is an ecosystem?
Briefly discuss enduring questions: What is an ecosystem and how does it
support life? What are the biotic (living) and abiotic (nonliving) components of an
ecosystem and how do they interact?
The first few clicks will reveal the words – biotic (living) and abiotic (non-living).
Each click will then bring up another word or words that describes the parts of an
ecosystem, beginning with the abiotic (nonliving components) and finishing with
the biotic (living components). As the different components are displayed discuss
their roles in the ecosystem and how they are important to life. Include the role
of sunlight, the water cycle, the importance of climate, weather and temperature,
nutrient cycles, energy flow, producers and consumers, predator/prey
interactions, etc.
Explain the importance of protists in an ecosystem. (Algae produces nearly 80 %
of the oxygen on the planet.) However, too much algae harms aquatic
ecosystems so animal-like protists consume algae (herbivores), algae and each
other (omnivores) or just each other (carnivores.) Explain that protists are the
basis for aquatic and terrestrial ecosystems (see attached food web) and that
without protists most ecosystem food webs would collapse.
Engage
(continued)
Slide 3: Focus Questions
Introduce the focus questions to the students. Have the students identify any
important vocabulary in the questions and determine what the words mean.
20 minutes
Explain
Slide 4: Micro-Ecosystems
Ask the students if they would like to see predator/prey in a drop of water. Exit
slideshow and minimize the PowerPoint. Click on the digital microscope to
open. Show the students the clean glass slide so that they know this is not a
trick! Take a small sample from a cloudy area of water on the surface of the
mini-pond culture. Drop two small drops directly onto the depression slide in the
center. Cover gently with the cover slip, taking care to avoid bubbles. Place the
slide under the digital microscope using the scanning objective (the shortest
objective). Locate the living protists. Point out to students that all of the living
things they are seeing are found in just two drops of water.
Slide 5: Protists
Show several of the video clips linked to this slide. Amoeba, paramecium, rotifer,
algae and daphnia. Discuss different methods of motility and food ingestion for
each of the protist examples (see attached documents for a description of the
various protists.
Ask the students how can they determine which single celled organisms perform
photosynthesis. Lead students to determine that the green protists are
producers. Show paramecium model. Discuss how single celled organisms
obtain energy. (some are producers, some are consumers)
Slide 6: Three Main Types of Protists
Introduce the three categories of protists: plant-like, animal-like, and fungus-like.
Direct the students to the posters of protists hanging on the wall and discuss the
three categories.
Roles of protists in the environment:
Explain
(continued)
Plant-like Protists – producers that gather their energy by
photosynthesis
Animal-like Protists – consumers that ingest other protists and organic
material. May be herbivores, omnivores, carnivores or scavengers
(detritus feeders)
Fungus-like Protists – decomposers that release chemicals that break
down the tissues of dead plants and animals.
Protists help maintain balance in ecosystems:
Algae produces 70-80 % of atmospheric oxygen and is the most
important producer in aquatic environments.
Decomposers are important for maintaining balance in ecosystems as
they feed on dead plants and animals and release nutrients back into
the soil and water.
Protists such as the paramecium are important predators of bacteria.
They are an essential food source for macroinvertebrates.
60 minutes
Explore
Tell the students that they are now going to go outside to the pond to collect
samples to bring back to the lab for exploration under the microscope. Explain
that they will need to be as careful as detectives to find the protists because they
cannot be seen with their eyes. Tell them that they will need to look for evidence
of protists.
Slide 7: Where do we find protists?
Ask: Where do we find protists? Have them repeat after you, “ooey-gooey
greasy-grimy slippery-slimy stinky stuff!”
Slide 8: Site Visits
Explain that they will be visiting 2 of the three possible sites at Fairview:
(Clockwise from top – Turtle Pond, Willow Pond, Toms Run.) Weather and
environmental conditions will determine which sites are visited. At each of the
two sites, the students are to make observations using the field microscopes and
then collect samples.
Slide 9: Onsite Exploration
Explain to students that they will be doing onsite explorations using
microviewers. Demonstrate for students the use of the microviewers, plastic
forceps and droppers, and collection jars. Stress the importance of taking care
of their equipment so that other students can use it. Have students inventory the
field pouch to make sure that they have all of their equipment and materials.
Stress that the better job they do as a field scientist, the more they will have to
look at under the microscopes in the lab when they return.
Explore
(continued)
Samples should be collected from near the shore in areas thick with algae and
dead plant debris, etc. Look for areas along the shoreline that have good
exposure to sunlight.
Slide 10: Safety First
Discuss SAFETY issues (see safety section above): Students are to use caution
around water areas. NO HORSEPLAY! Students are NOT to wade out into the
water at any time. All samples are to be collected using the extension poles with
collection cups or the large turkey basters. Remember that only four students at
a time are allowed out on the dock at turtle pond.
Slide 11: Collecting Samples
Students should have about 1 hour for the pond exploration.
Provide the students with the direction card.
Directions for Collecting Samples
Step 1
Step 2
Take a sample of water from each location and place it in your
microviewer container. Make sure the sample fills the well and that
there is “slimy stuff” - plant and decayed matter - in the sample.
Using your microviewer, look closely to see what might be moving in
the water. You need to be VERY patient looking for it.
Find a spot in the microviewer where you see some “stuff,” and be very
still. Watch carefully to see if anything moves. If you see a moving
organism, collect a larger sample from the pond or stream at the exact
same spot and place it in the correctly labeled sample container.
If you visit the stream you will be collecting scrapings from the rocks.
Select a rock that has water running over it. Look for brown or green
slime. Scrape the rock using the plastic forceps and place the sample
into the container with some stream water.
Replace cap tightly for transport back to the microscope lab.
Once you get back to the microscope lab, it is time to look more closely.
Make observations about the organisms you see. What size are they?
Do they move? If so, how? Are they any particular color? If so, what
might this tell you?
Step 3
Save the sample to transport back to the lab to view with the
microscope.
IMPORTANT!! INVENTORY ALL EQUIPMENT AND MATERIALS BEFORE
LEAVING A STUDY SITE.
Make sure that the students check all of their equipments and materials
before they leave each site so that nothing is left behind.
Tell the students that a good scientist and detective ALWAYS take care
of their equipment and materials!
Explore
(continued)
40 minutes
Slide 12: Prepare Slides for Microscopes
Back at the teaching site (microscope lab) students are to make slides from their
samples using the deep well slides and the compound microscopes. Now it is
time to look more closely. Help the students to prepare microscope observation
slides using the deep well slides. Covers are not necessary.
Explain
Slide 13: Parts of a Microscope
Refer the student to the picture of the microscope on slide 13 in the PowerPoint
presentation. Identify the parts of the microscope and demonstrate proper
focusing techniques. Make sure that the students know they are only to use the
short and the medium length objective, not the longest one. Explain that if they
attempt to use the longest objective with the plastic depression slide that the
objective will get scratched and be ruined. Then assist the students as they
focus the microscope, moving from low to medium power.
The students may then examine the organisms under the microscope. Have the
students make observations about the organisms.
Ask the following questions:
How do they move?
How do they eat?
How many different types of organisms do they see on the slide?
What do they think are the roles of the different organisms?
Help the students to understand that protists form the basis of all aquatic
ecosystems and that without a healthy protist community the entire aquatic food
web is in danger of collapse. Explain that there are protists that fit into every
category: Producer, consumer - herbivore, omnivore, carnivore, and
decomposer. Ask the students how the collapse of an aquatic food web would
impact terrestrial food webs.
Explain that aquatic systems are where most insects spend the majority of their
lives as macroinvertebrates and become winged for only a few days. Have the
students identify animals that depend on insects for food. (Examples include
birds, amphibians, reptiles, squirrels, skunks, bats, etc.) Challenge the students
to use the dichotomous protist key and the picture keys to identify the specific
type of organism they see under the microscope.
Explore
Extend
5 minutes
Slide 14: Size of Cells Link
Show the PowerPoint slide Cell Size and Scale.
http://learn.genetics.utah.edu/content/begin/cells/scale/
Click on the link and then slide the scale to show the students how small cells
are. Reinforce the importance of the microworld to ecosystems.
10 minutes
Slide 15: Check for Understanding
Ask: “How do we know that protists are alive?
Discuss each of the six characteristics. Ask the students to explain how the
protists fit each of the six characteristics.
Review the three main types of protists: Plant-like, animal-like, and fungus-like.
Review the role of producers and discuss the process of photosynthesis.
Emphasize that the sun drives photosynthesis and is the source of 99.9% of the
energy in ecosystems.
Evaluate
Ask: What is the role of protists in ecosystems? Discuss.
Slide 16: Focus and Enduring Questions
Enduring Questions
What is an ecosystem and how does it support life?
What are the biotic (living) and abiotic (nonliving) components of an
ecosystem and how do they interact?
Focus Questions
How would you describe and compare single celled and multicellular
organisms found in an aquatic ecosystem?
What are the roles and behaviors of single celled and multicellular
organisms in aquatic ecosystems?
Slide 17: Career Links
If time allows, as an additional extension, review the career links. Have the
students discuss what they did during the investigation may relate to any of the
careers on the slide.
10 minutes
Slide 18: Clean Up
Clean up is simple if you have the students follow these steps in order:
1. Have the students dump samples into the collection bucket and return
to their seats.
2. Demonstrate to the students the correct method of cleaning their
microscope and their workspace (from cleanest part to dirtiest part).
Show the students how to clean the microscope using the disinfectant
wipes in this order – eyepiece, focusing knobs, stage, base and table
around base. Hand out one hand-sanitizer wipe to each student.
3. Have the students use the same wipe to clean the slide and the
dropper.
4. Make sure that the field kit has all its contents, is zipped closed and is
returned to its place beside the microscope.
5. Place collection containers in the basket.
6. Return the plastic slide and dropper to the holder next to the base of the
microscope.
7. Place protective cover on microscope.
8. Collect the direction cards.
9. Throw wipe away in the trash and line up to wash hands at the sink with
soap and water. Make sure that the students wash their hands
thoroughly.
10. Dismiss the students as a group and accompany them to the group
meeting place as designated on the master schedule.
Cleaning Up
and Setting Up
for the Next
Teacher
Career Links
Considerations
for Larger
Groups
Inclement
Weather
Back-Up Plan
biologist
cytologist
histologist
embryologist
pathologist
For groups larger than 16 the students will need to share lab microscopes and field microscopes,
collection cups, etc. You will need to make sure that there are extra chairs for the students to sit
on, as the lab has only 16 stools.
If there is severe weather and students are not allowed outside, eliminate the collection portion of
the lesson and extend the PowerPoint presentation by including more video clips from the Nikon
website: http://www.microscopyu.com/moviegallery/pondscum/index.html
There will always be a collection bucket in the lab that contains the samples collected by previous
classes. The students can obtain samples from the bucket to explore under the microscope. If
desired, the teacher may provide the students with samples from the mini-pond culture. Just take
care to prevent the culture from being stirred or disturbed.
If the ponds are frozen solid, take the students to the stream to collect small slimy rocks. The
rocks will contain an amazing variety of diatoms and other protists even in the coldest of weather.
In extremely cold weather, minimize collection time and extend the PowerPoint time and
microscope viewing time.
Slide 1
Slide 2
Slide 3
Slide 4
Slide 5
http://www.microscopyu.com/movie
gallery/pondscum/paramecium/inde
x.html
http://www.microscopyu.com/moviegal
lery/pondscum/daphnia/index.html
http://www.microscopyu.com/m
oviegallery/pondscum/volvox/in
dex.html
PROTISTS
http://www.microscopyu.com/m
oviegallery/pondscum/collothe
ca/index.html
and
Microscopic Life:
Little Critters with a
BIG ROLE
http://www.microscopyu.com/m
oviegallery/pondscum/amoeba/i
ndex.html
Slide 6
Three Main Types of Protists
Plant-like
Protists
ALGAE
Animal-like
Protists
Fungus-like
Protists
AMOEBA
SLIME MOLD
Slide 7
Where do we find protists?
 Most
protists are found in ooey-gooey,
greasy-grimy, slippery-slimy, stinky stuff
that is around the edges and on the
bottom of aquatic ecosystems.
Slide 8
Slide 9
Onsite Exploration
Slide 10
SAFETY FIRST!
Slide 11
Collecting Samples
Slide 12
Slide 13
Parts of a Microscope
10x Ocular (Eyepiece)
Objective lenses
Coarse Focus
Stage
Fine Focus
Light Source
On/Off Switch
Base
Slide 14
Size of Cells Link
http://learn.genetics.utah.edu/content/begin/cells/scale/
Slide 15
How do we know that protists are
alive?
 Made
of one or more cells
 Obtain and use energy
 Produce waste products
 Exchange Gasses (CO2 and O 2)
 Grow and develop
 Reproduce
Slide 16
Focus Questions
 How
would you describe and compare
single celled and multicellular organisms
found in an aquatic ecosystem?
 What are the roles and behaviors of single
celled and multicellular organisms in
aquatic ecosystems?
Slide 17
Slide 18
Clean-up Time!
1.
2.
3.
4.
5.
6.
7.
Dump all samples into collection bucket.
Turn microscope OFF! Clean microscope,
starting with the eyepiece first.
Clean table area, dropper, and plastic slide.
Place protective cover on microscope.
Inventory microviewer kit, zip closed and
place by microscope.
Return sample collection jars to plastic tub.
WASH HANDS WITH SOAP AND WATER!
Color the following protists green: 1,3,5,6 8,9,12,13
Color the background: protist with cilia blue, protist with flagella orange, and protist in colonies yellow
Use the key to find the name of each protist and write the name of each protist in the box
Quick View for Cells
Teacher Materials
Materials/
Resources
Safety
digital microscope connected to a laptop which is
linked to a large LCD television screen
glass depression microscope slides
cover slips
dropper
pond water culture
Student Materials
(1of each item per student)
compound light microscopes
plastic depression viewing slides
dropper
field microscope with viewing chamber, plastic
syringe, plastic forceps and carrying case
specimen collection container
large collection syringe (turkey baster)
map of Fairview
compass
Students are to use caution around water areas.
Students should not wade into the water. Students should remain on the shore at all times.
No more than 4 students at a time should be on the Turtle Pond dock.
Students are not to walk on logs that have fallen into the water.
All samples are to be collected using the extension poles with collection cups or the large syringes.
Students should not handle living things, plants or animals, unless directed to do so by a Fairview Resource
Teacher.
Everyone should wash their hands thoroughly with soap and water at the end of the lesson.
Engage
Use slides 1-3 in the PowerPoint to introduce the lesson.
Explain
Use slides 4-6 in the PowerPoint to explain ecosystem, mico-ecosystems, and protists.
Explore
Use slides 7-11 in the PowerPoint for preparing for the onsite exploration and for collecting samples.
Explain
Use slide 12-13 in the PowerPoint to explain the parts of the microscope and demonstrating how to use the microscope.
Explore
Guide the students during their exploration of the organisms under the microscope.
Extend
Use slide 14 in the PowerPoint to show the link for the size of cells.
Evaluate
Use slides 15-17 in the PowerPoint to check for understanding and revisit the enduring and focus questions.
Clean Up
for the
Next
Teacher
Slide 18: Clean up is simple if you have the students follow these steps in order:
1. Have the students dump samples into the collection bucket and return to their seats.
2. Demonstrate to the students the correct method of cleaning their microscope and their workspace (from cleanest
part to dirtiest part). Show the students how to clean the microscope using the disinfectant wipes in this order –
eyepiece, focusing knobs, stage, base and table around base. Hand out one hand-sanitizer wipe to each student.
3. Have the students use the same wipe to clean the slide and the dropper.
4. Make sure that the field kit has all its contents, is zipped closed and is returned to its place beside the microscope.
5. Place collection containers in the basket.
6. Return the plastic slide and dropper to the holder next to the base of the microscope.
7. Place protective cover on microscope.
8. Collect the direction cards.
9. Throw wipe away in the trash and line up to wash hands at the sink with soap and water. Make sure that the
students wash their hands thoroughly.
Dismiss the students as a group and accompany them to the group meeting place as designated on the master schedule.