Download Multiplicity

Middle Grades Science
Multiplicity
EACH GROUP
TEACHER
paper towels
bag, zipper-lock, quart
scissors
beads, pony
string
Skittles®, single size bag
teacher-provided
materials
ABOUT THIS LESSON
T
his three-part lesson will familiarize students
with the events of the cell cycle. Part I asks
students to think analogously about mitosis
and cytokinesis by having them divide a “toy”
collection. Part II is a deliberate discussion about cell
division during which students map out a “schedule of
events” for cell division. Part III is teacher directed.
Using paper manipulatives, teachers lead students
through the stages of the cell cycle, beginning with
late interphase and ending with cytokinesis.
T E A C H E R
MATERIALS AND RESOURCES
P A G E S
Modeling the Cell Cycle
OBJECTIVES
Students will:
• Locate the correct structures of the cell
undergoing mitosis as the teacher describes the
function
• Model the processes of mitosis and cytokinesis
LEVEL
Middle Grades: Life
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
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Middle Grades Science – Multiplicity
NEXT GENERATION SCIENCE STANDARDS
COMMON CORE STATE STANDARDS
(LITERACY) RST.6-8.1
Cite specific textual evidence to support analysis of
science and technical text.
DEVELOPING AND
USING MODELS
(LITERACY) RST.6-8.3
Follow precisely a multistep procedure when carrying
out experiments, taking measurements, or performing
technical tasks.
(LITERACY) WHST.6-8.1
SYSTEMS AND
SYSTEM MODELS
Write arguments focused on discipline-specific
content.
CONNECTIONS TO AP*
ASSESSMENTS
AP
BIOLOGY
2
*Advanced Placement® and AP® are registered trademarks of the
College Entrance Examination Board. The College Board was not
involved in the production of this product.
The following assessments are embedded in this
lesson:
• Assessment of prior knowledge of cell structure
• Student-led modeling of cell cycle
T E A C H E R
Write informative/explanatory texts, including the
narration of historical events, scientific procedures/
experiments, or technical processes.
LS1: STRUCTURES
AND PROCESSES
P A G E S
(LITERACY) WHST.6-8. 2
• Demonstration of random stages in the cell cycle
The following assessments are located on our website:
LESSON CONSUMABLES
• Lesson Assessment: Mitosis, Mardi Gras Style
Item 1 – Chromosome Manipulative (1/2)
• Middle Grades Life: Heredity
Item 2 – Chromosome Manipulative (2/2)
ACKNOWLEDGEMENTS
Skittles® is a registered trademark of the Wm. Wrigley
Jr. Company, a division of Mars, Inc.
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
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Middle Grades Science – Multiplicity
TEACHING SUGGESTIONS
This lesson uses candies and pony beads contained
in a plastic sandwich bag to represent the “mess” that
students must organize before separating out their
“toys.” Other items can be used as long as there is a
subset that can be separated from the larger “mess.”
Colored paper clips can be separated from a larger
collection of office supplies, for example. Also, be
sure that whatever items represent the toys in this
scenario are present in an even number to facilitate the
equal distribution of toys and thus genetic material. A
sample plastic bag might include four red, two green,
four yellow, two orange, and two purple candies and
any number of colored pony beads.
Part III is teacher-directed. After identifying and
describing the paper manipulatives, you will lead
students through the stages of the cell cycle beginning
with late interphase and ending with cytokinesis.
Note that the homologous chromosomes have
the same shape but may have different striping to
represent different alleles. Be sure students have
enough string to create a cell membrane, nuclear
membrane, and eight spindle fibers (one for each of
the chromosomes).
P A G E S
In Part I, students will grasp that a system is required
to divide the toys. Just as the daughter cells result
from a series of regulated steps so, too, is the division
of toys not random. It is important for you to ask
questions that will lead students to understand that
mitosis differs in the fact that a parent cell has the
exact same number of chromosomes as the two
daughter cells. This gives you an opportunity to
emphasize that cell mitosis and the subsequent
cytokinesis is not simply “dividing in half.”
Part II is a deliberate discussion in which students
map out a “schedule of events” of cell division. At
this point, students do not need to know the exact
terminology of chromatin, chromosome, and sister
chromatid. You can name them if the students begin
to describe these structures. However, they will need
to be familiar with cytoplasm, cell membrane, and
nuclear membrane. Encourage students to think about
these structures and what—if any—changes must
occur for the chromosomes to duplicate and the cell
to divide. Suggested bell work would be to ask your
students to label the parts of a cell which would also
serve as a quick formative assessment.
T E A C H E R
T
his lesson is three-part activity that uses
candies and paper chromosomes to help
students learn the stages of the cell cycle. Part
I is a scenario in which students must figure out a way
to divide their toy collection so that they may donate
their duplicates to charity. Although quite simple, this
part of the activity is meant to help students think
analogously about the events that must occur during
cell division.
Go through the stages once without student input,
allowing time for students to record their observations.
During the second pass-through, encourage students to
tell you how the manipulatives should appear. During
the third pass-through, call out random stages of the
cell cycle and ask your students to demonstrate these
stages using their manipulatives.
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Middle Grades Science – Multiplicity
TEACHING SUGGESTIONS (CONTINUED)
Interphase is the longest portion of the cell’s life
cycle and is typically referred to as a “cell at rest.”
The cell is not truly resting at this point, but rather
it is not undergoing cellular division or mitosis. Cell
division, the second phase of the cell cycle, takes
place to create genetically identical daughter cells. In
multicellular organisms, cells undergo cell division for
the organisms to develop. Single-celled organisms that
undergo mitotic cell division do so to reproduce.
Eukaryotic cell division consists of two stages:
mitosis and cytokinesis. Mitosis is the duplication of
the chromosomes and results in the formation of two
nuclei. Cytokinesis is the distribution of the organelles
and cytoplasm and results in the formation of two
identical daughter cells. When cells are damaged or
as cells die, new cells must be created to replace these
cells. The mitosis phase consists of four stages.
INTERPHASE
The cell is between divisions during interphase, which
consists of three phases: G1, S, and G2. During G1
the cell is typically “at rest” and undergoing protein
synthesis. The uncoiled DNA is in the nucleus and
called chromatin. During the S phase, DNA undergoes
DNA replication. During the G2 phase, the cell
continues to swell and some proteins continue to be
formed while the centrioles complete duplication
PROPHASE
The long, stringy, unwound chromatin fibers coil and
condense into thick threads of visible genetic material
called chromosomes. As the cell enters prophase, the
chromosomes have already been replicated forming
sister chromatids. The sister chromatids are connected
to each other at the centromere. The spindle apparatus
begins to form and the nuclear membrane breaks down
while the nucleolus disappears (“pro-” means first or
before).
METAPHASE
The centromeres of the sister chromatids line up along
the center, or metaphase plate, of the cell bringing the
genetic material to the center of the cell. Microtubules
connect the centromere of each chromosome to the
spindle apparatus via the centriole (“meta-” means
middle).
ANAPHASE
The centromere of each chromosome divides,
separating the sister chromatids from each other. The
sister chromatids are separated because the spindle
apparatus is becoming shorter, thereby pulling
the chromatids to opposite sides of the cell. The
chromatids of each pair will be moved by the spindle
fibers toward opposite poles of the cell. The separated
chromatids are called chromosomes. This separation
allows one copy of each type of chromosome to be
placed on opposite sides of the dividing cell (“ana-”
means away).
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
P A G E S
Individual cells within an organism go through various
stages of growth and division. These stages are
referred to as the cell cycle. The life cycle of a cell, or
the cell cycle, can be separated into two main phases:
interphase and cell division.
inside the centrosome (“inter-” means between).
T E A C H E R
THE CELL CYCLE
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Middle Grades Science – Multiplicity
TEACHING SUGGESTIONS (CONTINUED)
TELOPHASE
GLOSSARY
The final stage of mitosis occurs as new nuclear
membranes are formed around both groups of
chromosomes. The result is two separate nuclei, each
containing the same genetic information as the original
cell’s nucleus. The chromosome will uncoil and loosen
up to form chromatin threads. The spindle fibers break
apart, and nucleoli are reformed. (“telo-” means end or
far away).
Centromere – The centralized region joining two sister
chromatids.
Chromatin – The aggregate mass of dispersed genetic
material formed of DNA and protein and observed
between periods of cell division in eukaryotic cells.
Chromosome – Structure containing genetic
information in the nucleus of all eukaryotic cells and
visible during mitosis and meiosis. Chromosomes
consist of DNA and protein.
Sister chromatids – Replicated forms of a chromosome
joined together by the centromere and eventually
separated during mitosis.
Spindle fiber – A grouping of microtubules that move
chromosomes during cell division. This is also known
as the spindle apparatus.
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
P A G E S
The cell may now undergo the final stage of the cell
cycle in which the cytoplasm divides. In animal cells,
the onset of cytokinesis is marked by the presence
of a cleavage furrow. The cell membrane is drawn
inward until the cytoplasm is split into two separate
parts forming two distinct cells. In plant cell, cells
cytokinesis results from the formation of a cell plate
between the two newly formed nuclei. As the cell wall
grows, it separates the nuclei into two distinct cells
(“cyto” means cell and “kinesis” means movement).
Chromatid – One half of a replicated chromosome.
T E A C H E R
CYTOKINESIS
Centrosome – The centrosome is also called the
“microtubule organizing center.” The centrosomes in
animal cells contain the centrioles. Centrosomes are
found in plant cells but do not contain centrioles.
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Middle Grades Science – Multiplicity
DATA AND OBSERVATIONS
PART III: MODELING THE CELL CYCLE
Table 1. Important Structures of Cell Division
Summary
Chromatin
The uncoiled DNA is in
the nucleus and is called
chromatin.
Chromosome
The long, stringy, unwound
chromatin fibers coil and
condense into thick threads
of visible genetic material
called chromosomes.
Sister chromatid
Chromosomes have already
been replicated, forming
sister chromatids. The sister
chromatids are connected
to each other at the
centromere.
Centromere
The attachment point
for spindle fibers to the
chromosome.
Centriole
Help create and organize the
mitotic spindle fibers.
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K E Y
Illustration
A N S W E R
Structure
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Middle Grades Science – Multiplicity
DATA AND OBSERVATIONS (CONTINUED)
Table 2. Stages of Cell Division
Summary
End of
interphase
The cell is between divisions during
interphase, which consists of three
phases: G1, S, and G2. During G1,
the cell is typically “at rest” and
undergoing protein synthesis. The
chromosomes are coiled together
in the nucleus and are called
chromatin.
Prophase
The long, stringy, unwound chromatin
fibers coil and condense into thick
threads of visible genetic material
called chromosomes.
Metaphase
The centromeres of the sister
chromatids line up along the center,
or metaphase plate, of the cell,
bringing the genetic material to the
center of the cell.
Anaphase
The centromere of each chromosome
divides, separating the sister
chromatids from each other. The
chromatids of each pair will be
moved by the spindle fibers toward
opposite poles of the cell. The
separated chromatids are called
chromosomes.
Telophase
The final stage of mitosis occurs
as new nuclear membranes are
formed around both groups of
chromosomes. The result is two
separate nuclei, each containing
the same genetic information as the
original cell’s nucleus.
Cytokinesis
The final stage of the cell cycle in
which the cytoplasm divides. In
animal cells, the onset of cytokinesis
is marked by the presence of a
cleavage furrow. The cell membrane
is drawn inward until the cytoplasm is
split into two separate parts, forming
two distinct cells.
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
K E Y
Illustration
A N S W E R
Stage
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Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS
Answers will vary.
2. A complete set of chromosomes for an organism
that reproduces sexually consists of genetic
material from a father and mother. This number is
described as 2n. Somatic cells in humans have
2n = 46 chromosomes.
Assuming our model organism in Part III
reproduces sexually, what is its value of 2n?
2n = 4
3. How many chromosomes does the organism in
Part III have during each of the modeled stages
detailed in Table 3?
Table 3. Chromosome Numbers
During the Cell Cycle
1. Models and simulations are useful because they
allow us to study phenomena that are otherwise
too small or too complicated to observe. Few
models can replicate the actual phenomenon
perfectly, however. Identify and explain one
limitation of Part I, the toy activity.
Answers will vary. Cells undergoing mitosis
begin and end with the same number of
chromosomes.
2. The illustrations shown in Figure 1 are of onion
(Allium cepa) root tip cells in various stages of
the cell cycle.
Look at the center cell of each illustration and
determine if the cell is in interphase, prophase,
metaphase, anaphase, or telophase. Record the
stage on the line provided below the image.
K E Y
1. Go back and review your procedure for
separating and donating your toys. Identify steps
in your procedure that are similar to stages in the
cell cycle.
Stages from left to right:
• Prophase
Stage
Number of Chromosomes
in the Cell
• Anaphase
End of interphase
4
• Interphase
Prophase
4
Metaphase
4
Anaphase
8
Telophase
8
Cytokinesis
4
A N S W E R
ANALYSIS
• Telophase
• Metaphase
3. After examining a prepared slide of an onion root
tip, a student observes that some stages of the cell
cycle are more prevalent than others. The number
of cells she counted in each stage is recorded in
Table 4.
Develop a pie graph representing the data from
Table 4.
See Figure A.
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Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS (CONTINUED)
Telophase
Anaphase
Metaphase
Prophase
4. The cell cycle for an onion root tip cell lasts 12
hours. Determine the amount of time in minutes
that each stage lasts. Assume that the likelihood
of observing a cell in a particular stage directly
relates to the time the cell spends in that stage.
a. Interphase – 562 minutes
b. Prophase – 101 minutes
c. Metaphase – 36 minutes
d. Anaphase – 7 minutes
e. Telophase – 14 minutes
5. A cell in interphase in the leaf of a tomato plant
has 12 chromosomes. A second cell in the plant
is undergoing mitosis. Under the microscope,
it appears as though the chromatids are being
pulled to the poles of the cell. Identify the stage
of mitosis that the cell is in and determine the
number of chromosomes in the cell during this
stage.
The stage of mitosis is anaphase. During
anaphase, this cell would have 24 chromosomes.
A N S W E R
Figure A. Percentages of chromosome numbers during the cell cycle
K E Y
Interphase
6. Tissue samples have been collected from a
patient with lung cancer. It was discovered that
the cancerous cells are undergoing mitosis at a
more rapid pace than normal lung cells. How
would this be detrimental to the healthy lung
cells?
When the cell is “at rest” in interphase, one of its
main functions is to synthesize proteins. When
cells are undergoing mitosis at a faster rate, the
amount of time that the cell undergoes such
normal functions as protein synthesis decreases.
This will impact the tissue, the organ, the system
and, ultimately, the entire organism.
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ix
Middle GradesMiddle
Science
Grades
– Multiplicity
Science
Multiplicity
Modeling the Cell Cycle
T
MATERIALS
paper towels
scissors
string
teacher-provided materials
hey say that growing up is hard to do. Getting older means understanding
more about how the world works, greater responsibility, and knowing how
our actions affect the world around us. It never stops. And as if you needed
one more reminder of how your world is changing, your mom has asked you to
get rid of all of your duplicate toys.
“You have too many action figures, too many building blocks, too many dolls,”
she says. “How do you have so many toys that are identical? We—you—can
donate some of them. Go through your room and divide them up. I’ll bring you
two boxes. Figure out an orderly way. Put the ones you want to keep in one box
and the remaining toys in the other.”
It won’t be as easy as just splitting your toy collection in half, but it won’t be too
difficult either. Your collection is large but you have those duplicates, so it will
not be that big of a deal to give some away. But you survey your room, and it’s a
mess. You need a plan. What is it?
Growing is a characteristic of life, and organisms grow when their cells get bigger
or when they make new cells. The process of creating new cells from existing
cells is called cell division and its exactly what it sounds like: dividing a cell into
two cells. Mitosis is when the two cells created are identical. Unlike the boxes of
toys, the daughter cells must each contain the same number of chromosomes as
the parent cell.
What does “eukaryotic”
mean?
Eukaryotic cell division consists of two phases: the division of nuclear material
and the division of everything else into two cells. The division of nuclear material
is called mitosis, and the division of the cytoplasm and all the organelles is known
as cytokinesis. The end result of cell division, also called the M phase, is the
formation of two identical daughter cells.
One way to remember
what “cytokinesis”
means is to dissect the
word and determine the
meaning of its parts.
What is the prefix in
cytokinesis? The root
word? What do they
mean?
What happens when a cell is not dividing? It is doing what it is supposed to be
doing. A liver cell is filtering wastes from your blood. Lung cells are facilitating
the exchange of oxygen and carbon dioxide. This part of a cell’s life is called
interphase. Interphase and M phase together make up the complete cell cycle of
growth and division.
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Middle Grades Science – Multiplicity
PURPOSE
In this activity, you will generate a procedure to reliably separate duplicated toys
(candies) and compare this process to the phases of the cell cycle.
PROCEDURE
PART I: THINKING ANALOGOUSLY
1. Remove the “toys” from the bag and spread them out.
2. Generate a method of separating the “toys” in an orderly fashion.
3. Record your procedure on your student answer pages.
PART II: ANTICIPATING MITOSIS
Think about the
structure of the cell. Are
there certain structures
that are in the way or
must change for cell
division to occur?
Cell division begins with one cell and ends with two identical daughter cells.
What events have to occur for the daughter cells to have the same number of
chromosomes as the mother cell? Develop a “schedule of events” or procedure for
cell division and record your steps.
PART III: MODELING THE CELL CYCLE
Using paper chromosomes and string, your teacher will model the cell cycle. With
your own set of chromosomes and string, you will follow along.
On your student answer pages, you will record:
• An illustration and description of each of the important structures of cell
division (Table 1)
• An illustration and summary of each of the stages of the cell cycle (Table 2)
Be aware that although we have identified and named the stages of the cell cycle,
the events occur in one continuous process.
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Middle Grades Science – Multiplicity
DATA AND OBSERVATIONS
PART I: THINKING ANALOGOUSLY
Use this space to record your procedure for separating your “toys.”
PART II: ANTICIPATING MITOSIS
Use this space to record your anticipated schedule of events for mitosis.
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Middle Grades Science – Multiplicity
DATA AND OBSERVATIONS (CONTINUED)
PART III: MODELING THE CELL CYCLE
Table 1. Important Structures of Cell Division
Structure
Illustration
Summary
Chromatin
Chromosome
Sister chromatid
Centromere
Centriole
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Middle Grades Science – Multiplicity
DATA AND OBSERVATIONS (CONTINUED)
Table 2. Stages of Cell Division
Stage
Illustration
Summary
End of
interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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5
Middle Grades Science – Multiplicity
ANALYSIS
1. Go back and review your procedure for separating and donating your toys.
Identify steps in your procedure that are similar to stages in the cell cycle.
2. A complete set of chromosomes for an organism that reproduces sexually
consists of genetic material from a father and mother. This number is
described as 2n. Somatic cells in humans have 2n = 46 chromosomes.
Assuming our model organism in Part III reproduces sexually, what is its
value of 2n?
3. How many chromosomes does the organism in Part III have during each of
the modeled stages detailed in Table 3?
Table 3. Chromosome Numbers During the Cell Cycle
Stage
Number of Chromosomes in the Cell
End of interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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6
Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS
1. Models and simulations are useful because they allow us to study phenomena
that are otherwise too small or too complicated to observe. Few models can
replicate the actual phenomenon perfectly, however. Identify and explain one
limitation of Part I, the toy activity.
2. The illustrations shown in Figure 1 are of onion (Allium cepa) root tip cells
in various stages of the cell cycle.
Figure 1. Onion root tip
cells
Look at the center cell of each illustration and determine if the cell is in
interphase, prophase, metaphase, anaphase, or telophase. Record the stage on
the line provided below the image.
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7
Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS (CONTINUED)
3. After examining a prepared slide of an onion root tip, a student observes that
some stages of the cell cycle are more prevalent than others. The number of
cells she counted in each stage is recorded in Table 4.
Table 4. Number of Cells in Each Phase
Cell Phase
Numbers of Cells Observed
Interphase
78
Prophase
14
Metaphase
5
Anaphase
1
Telophase
2
Develop a pie graph representing the data from Table 4.
A pie graph is very
similar to the face of a
clock.
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8
Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS (CONTINUED)
4. The cell cycle for an onion root tip cell lasts 12 hours. Determine the
amount of time in minutes that each stage lasts. Assume that the likelihood
of observing a cell in a particular stage directly relates to the time the cell
spends in that stage.
a. Interphase
b. Prophase
c. Metaphase
d. Anaphase
e. Telophase
5. A cell in interphase in the leaf of a tomato plant has 12 chromosomes. A
second cell in the plant is undergoing mitosis. Under the microscope, it
appears as though the chromatids are being pulled to the poles of the cell.
Identify the stage of mitosis that the cell is in and determine the number of
chromosomes in the cell during this stage.
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
9
Middle Grades Science – Multiplicity
CONCLUSION QUESTIONS (CONTINUED)
6. Tissue samples have been collected from a patient with lung cancer. It was
discovered that the cancerous cells are undergoing mitosis at a more rapid
pace than normal lung cells. How would this be detrimental to the healthy
lung cells?
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
10
Middle Grades Science – Multiplicity
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
C O N S U M A B L E
L E S S O N
Cut lines are solid. Fold lines are
dashed.
ITEM 1 – CHROMOSOME MANIPULATIVE (1/2)
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Middle Grades Science – Multiplicity
Copyright © 2013 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org.
C O N S U M A B L E
L E S S O N
Cut lines are solid. Fold lines are
dashed.
ITEM 2 – CHROMOSOME MANIPULATIVE (2/2)
12