Download How a Cell Works

Science 7 Standard 4 08-06
8/22/02
7:49 AM
Page 143
Standard Indicator
7.4.5
How a Cell Works
Purpose
Students will explain that the basic function of organisms, such as
extracting energy from food and getting rid of wastes, are carried out
within the cell and understand that the way in which cells function
is similar in all organisms.
Materials
English/
Language Arts
Have students write
narratives explaining
their journeys through
a cell on a typical
day. Instruct them
to include the functions
of organelles in
their stories.
extending
THE
Activity
A. Pre-Activity Preparation
Have a stovetop available or use beakers and hot plates to prepare
the gelatin and boil spaghetti until it is just pliable.
B. Pre-Activity Discussion
1. Ask students: “What are the basic functions of organisms?”
2. Discuss students’ responses; be sure to discuss how organisms
consume food for energy, reproduce, get rid of wastes, grow, etc.
3. Explain to students that the basic functions of an organism take
place at a cellular level. Explain that organisms are made up
of cells and that although not all cells are exactly the same
(e.g., muscle cells and skin cells), they all carry out basic functions
necessary for an organism to survive.
C. Animal Cells and Plant Cells
1. Distribute a copy of the BLM Cell Diagrams to each student
and show the transparency of the BLM.
2. Explain that even though most cells are microscopic, many
contain many tiny parts called organelles.
(continued)
Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002
curriculum
ACTIVITY
Explain the function
of the liver and ask
students which of the
organelles studied
might be present
in large quantities in
liver cells [lysosomes].
Relate the functions
of other organs to the
number of organelles
present (e.g.,
mitochondria in
muscle cells).
Standards Links
7.4.1, 7.4.4,
7.4.8, 7.7.2
page 143
Standard 4
For the teacher: transparency of Black Line Master (BLM) Cell
Diagrams, overhead projector, hot plate and beakers or stovetop
and pan
For each student: copy of BLMs Cell Diagrams and Gelatin Cells
For each group of students: sparkling grape gelatin mix and water
[cytoplasm], plastic bag [cell membrane], plastic container with lid
[cell wall], small plum [nucleus], mandarin orange slices [mitochondria],
green grapes [chloroplasts], dried apricots [Golgi complex], half-cooked
spaghetti [smooth and rough endoplasmic reticulum], poppy seeds
[for surface of rough endoplasmic reticulum], red grape [lysosome],
small balloon [vacuole], toothpick
connecting
across the
Science 7 Standard 4 08-06
8/22/02
7:49 AM
Page 144
Activity (continued)
3. Use the overhead to explain how each organelle has a
specific function.
4. Explain that animal cells and plant cells are similar since they
both have organelles, which carry out similar functions.
5. Explain that there are also differences between plant and animal
cells (e.g., plant cells have cells walls and chloroplasts, which
allow them to make their own food through photosynthesis).
Standard 4
D. Activity
1. Acknowledge that although they are viewing two-dimensional
models of cells, cells are actually three-dimensional.
2. Divide students into groups and distribute a copy of the BLM
Gelatin Cells to each group. Direct half of the students to build a
plant cell model and half to build an animal cell model.
3. Distribute the materials listed on the BLM Gelatin Cells and
direct students to use the BLM Cell Diagrams to build models.
4. Monitor students as they work. Ask questions, such as:
Which materials could represent each part of the cell in
your model? [gelatin/cytoplasm, plastic container/cell wall,
plastic bag/cell membrane, green grape/chloroplast, etc.]
Which organelle is responsible for extracting energy from foods
for cell work? [mitochondria] Which is responsible for getting
rid of wastes? [lysosomes]
What makes all cells similar? What makes them different from
each other? [All cells carry out some basic functions, but there
are specialized cells in different parts of an organism that
perform specialized functions.]
5. After the gelatin sets in the refrigerator and the cells are
complete, have students retrieve their cells and examine them.
6. Ask students questions such as: “Do all of the ‘cells’ have the
same shape?” [Compare how the animal cells vary in shape,
but plant cells do not vary as much since they were surrounded
by a rigid cell wall.]
Classroom Assessment
Basic Concepts and Processes
At the end of the activity, ask questions, such as the following:
How are the basic functions of an organism carried out
at the cellular level?
How do all cells function similarly?
What might happen if a number of organelles in a cell did not
function properly? Give an example.
How can you tell a plant cell from an animal cell?
page 144
Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002
Science 7 Standard 4 08-06
8/22/02
7:49 AM
Page 145
Name:
Cell Diagrams
Animal
Plant
cell
membrane
mitochondrion
smooth
endoplasmic
reticulum
cell
membrane
cell wall
mitochondrion
nucleus
central vacuole
golgi
apparatus
smooth
endoplasmic
reticulum
lysosome
nucleus
golgi
apparatus
rough
endoplasmic
reticulum
chloroplast
rough endoplasmic reticulum
Each organelle has a specific job, such as the following:
Nucleus, “The Control Center”: stores genetic information which has directions for cell division,
the production of proteins, etc.
Lysosomes, “The Garbage Disposal”: found in animal cells; breaks down and excretes cell wastes
Mitochondria, “The Power House”: respiration takes place here; food energy is converted into chemical
energy for the cell to work
Smooth Endoplasmic Reticulum: makes substances such as fats and steroids
Rough Endoplasmic Reticulum: makes proteins, which get changed and packaged for specific jobs
in the Golgi Apparatus (or Golgi Body)
Central Vacuole: found in plant cells; stores wastes and water (central vacuoles store cellular products,
food, and waste in most types of cells)
Chloroplast: not found in animal or fungal cells; where photosynthesis takes place
Organelles are held in place by cytoplasm, and cells are enclosed by membranes which allow certain
substances to enter and leave.
Plant (and fungal) cells have a second covering called a cell wall, which makes the cells rigid.
Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002
Black Line Master 1
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Science 7 Standard 4 08-06
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7:49 AM
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Cell Diagrams
Teacher Directions
Make a transparency copy of the BLM Cell Diagrams. In addition, make a photocopy of the BLM
Cell Diagrams for each student. Distribute a copy of the BLM to each student and show the
transparency, explaining the functions of each organelle.
Answer Key
Not applicable.
Black Line Master 1
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Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002
Science 7 Standard 4 08-06
8/22/02
7:49 AM
Page 147
Name:
Gelatin
Cells
Create a Cell Model
Materials:
Sparkling grape gelatin mix, water, plastic bag, twist tie, large mixing bowl, spoon, plastic
container with lid, mandarin orange slices, plums, green grapes, dried apricots, half-cooked
spaghetti, poppy seeds, red grapes, small balloon, toothpick
Plans for creating your model:
1. Will you create a plant or animal cell model?
2. Which organelles/cell parts will you need to represent in your plant or animal cell model?
3. Which materials listed best represent each organelle and cell part?
Procedure:
1. Write your names on the plastic bag.
2. Boil water and follow directions on the package to make the gelatin.
3. Fill the plastic bag with gelatin and the organelles.
4. Seal the bag with a twist tie.
5. If you are making a plant cell model, place the bag into a plastic container and seal the lid.
Then, stack your model with other plant cell models in the refrigerator for the gelatin
to harden.
6. If you are making an animal cell model, stack your model with other animal cell models
in the refrigerator for the gelatin to harden.
7. When the gelatin has set, remove your cell from the refrigerator and compare it with the rest
of the class cells.
Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002
Black Line Master 2
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Science 7 Standard 4 08-06
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7:49 AM
Page 148
Gelatin Cells
Teacher Directions
Distribute a copy of the BLM Gelatin Cells to each group of students. Direct half of the students
to create a plant cell model and the other half to create an animal cell model. Distribute the
materials listed on the BLM and direct students to decide which materials should represent
each part of the cell model.
Answer Key
Below are the suggested materials to represent different organelles:
sparkling grape gelatin [cytoplasm]
plastic bag [cell membrane]
plastic container with lid [cell wall]
small plum [nucleus]
mandarin orange slices [mitochondria]
green grapes [chloroplasts]
dried apricots stuck together with a toothpick [Golgi complex]
half-cooked spaghetti [smooth endoplasmic reticulum]
half-cooked spaghetti with poppy seeds [rough endoplasmic reticulum]
red grape [lysosome]
small inflated balloon [vacuole]
Black Line Master 2
page 148
Standard 4 / Activity 3
Indiana Science Grade 7 Curriculum Framework, October 2002