5E Inquiry Lesson Plan Procedures

5E Inquiry Lesson Plan
Title: MODELING MITOSIS
Grade level: 7th
National Standards:
National Science Education Standards for Life Science Content,
Standard C, grades 5 – 8 (structure and function in living systems, reproduction and
heredity).
ACOS:
2, 8, 9
Objectives:
1. The student will model mitosis to identify and describe the process in full or in any
one of the stages.
2. The student will recognize and sketch any one of the stages of Mitosis from prepared
slides of an onion root tip and a white fish blastula.
3. The student will explain Mitosis to group members as he models the process.
Procedures
Materials:
Cheek Cell Lab: toothpicks, dropper bottle of water, blank slides, cover slips,
Methylene Blue, microscopes, plastic container with dilute bleach solution.
Modeling: Per Eight Groups---4’x2’ bulletin board paper, one 100 inch piece black
yarn, one 60 inch piece purple yarn, two 30 inch pieces of rust yarn, two 32 inch pieces
of rust yarn, two 36 inch pieces of rust yarn, two 12 inch pieces of red yarn, two 12 inch
pieces of blue yarn, scissors, scotch tape, 4 rubber bands, 4 red popsicle sticks, 4 blue
popsicle sticks.
Observation of Mitosis: Microscopes, prepared slides of onion root tip, prepared
slides of whitefish blastula
Word Documents for Taboo Cards and Karyotyping Activity
1
Engage
Time: Two 50 minute class periods
--Pre Test
--Questions to Ponder
--3D Interactive Microscope
--Cheek Cells Lab
Explore
Time: Two 50 minute class periods
--Modeling Mitosis
--Observe, draw and label one phase of Mitosis in whitefish blastula slides and onion
root tip slides
Explain
Time: One 50 minute class period
---Power point
---Questions based on Modeling Activities
Elaborate
Time: Same 50 minute time period as Explain
--Taboo Genetic Vocabulary Game
--Karyotyping Activity (do this activity on the same day as the post test)
Evaluate
Time: One 50 minute time period (see above)
--Post Test
Safety: N/A
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter 2013
2
TEACHER PRE-LAB GUIDE
ENGAGE:
Questions to Ponder: Place the questions on a flip-chart, handout, poster, etc. for
interactive class discussion.
1. How does a human being grow from a single fertilized cell into an individual
containing billions of cells?
Answer: Cells increase their number through a process called cytokinesis or cell
division. Cell division is preceded by nuclear division or mitosis. The genetic
information of the parent cell is reproduced exactly in each daughter cell, whereas
division of the other cell components is not exact.
2. Do all of the cells of the body look like one another? Do they perform the same
jobs?
Answer: There are many different types of cells in the body which serve many different
functions. A nerve cell which conducts electrical messages looks very different from a
cheek cell. Cheek cells are a type of epithelial tissue which are tightly arranged to help
protect against bacterial invasion.
3. Do all cells of the body contain the same genetic information?
Answer: All cells in the body with the exception of the egg and the sperm have identical
copies of an individual’s genetic information. Different genes are activated in different
cell types.
4. How is the genetic blue print that makes you who you are transmitted continually
from one cell to the next?
Answer: The consistent transmission of genetic material from one cell generation to the
next is accomplished through DNA replication during Interphase and division in the
process of mitosis. This nuclear replication and division occurs billions of times with
great accuracy as a human being grows and develops.
5. How long does it take for one parent cell to become two daughter cells?
Answer: In humans, rapidly dividing cells such as skin and gut divide as often as once
a day. Other cells, such as brain and nerve tissue, rarely divide in an adult.
6. Are cells alive?
1
Answer: Yes, they are the smallest units of life. They are considered to be living
because they are capable of respiration, nutrient intake, release of waste materials,
reproduction of themselves, movement, responsiveness and other processes which are
characteristic of other living things.
7. What is a cell anyway?
Answer: Cells are sometimes referred to as the basic units of life; they are small
compartments in your body which house your DNA and perform all the essential tasks
to sustain life. They are surrounded by a cell membrane, contain a nucleus surrounded
by a nuclear membrane and have many other organelles performing various functions.
Interactive Microscope:
Review the parts of the microscope and their functions using the interactive microscope.
The Human Cheek Cell Lab:
Materials:
Toothpicks (throw away after use)
Dropper bottle of water
Blank slides
Cover slips (throw away after use)
Methylene Blue dropper bottle
Microscope
Plastic container with dilute bleach solution for used slides
Handout - Answer Key is attached
2
EXPLORE:
MODELING:
Materials:
Each of the eight groups need:
4’ long by 2’ wide bulletin board paper
Black, purple and rust yarn: one 100 inch piece of black yarn; one 60 inch piece of
purple yarn; two 30 inch pieces of rust yarn (green twist tie); two 32 inch pieces of rust
yarn (blue twist tie); two 36 inch pieces of rust yarn (red twist tie).
Two 12” pieces of red yarn
Two 12” pieces of blue yarn
Scissors
Scotch tape
Rubber bands
Four red popsicle sticks
Four blue popsicle sticks
PREPARATION:
Set up 8 stations with the materials listed above
PROCEDURE:
Hand out Student Lab Guide 1 (Modeling Mitosis) to each group
MICROSCOPE OBSERVATION OF MITOSIS:
Materials:
Microscope
Prepared slides of Onion Root Tip and Whitefish Blastula
PREPARATION:
Set up 4 microscopes with Onion Root Tip slide at 40X
3
Set up 4 microscopes with Whitefish Blastula slide at 40X
PROCEDURE:
Hand out Student Lab Guide 2 (Mitosis Observation) to each group
ANSWERS TO QUESTIONS: STUDENT LAB GUIDE 1
PART A: (pages 2 and 3)
1. Diploid means there are two copies of each chromosome in the cell. For humans,
this means 22 pairs of autosomes (44 total) and one pair of sex chromosomes (2 total).
Most higher organisms are diploid. One chromosome set is inherited from the female
parent through the egg and the other chromosome set is inherited from the male parent
through the sperm (or in plants, through pollen).
2. All human cells are diploid with the exception of the sperm and egg cells. Sperm
and egg cells, also known as gametes, are haploid. They have only one copy of each
chromosome or 23 total chromosomes.
3. A diploid organism, such as a human, has 2 of each kind of chromosome, one from
the father and one from the mother. The matching or homologous chromosome has
similar size and shape, and they carry the same genes arranged in the same order.
However, the particular version (allele) of each gene may not be the same on the 2
homologous chromosomes. For example, considering the homologous pair of red
chromosomes, one of the red chromosomes may have a gene that codes for red hair
color while the other red chromosome has a gene that codes for orange hair color.
4. There are two pairs of homologous chromosomes in the Dibble cell. One pair of red
yarn/popsicle sticks and one pair of blue yarn/popsicle sticks for a total of 4 unreplicated
chromosomes.
5. The two red chromosomes should be circled as a pair; the two blue chromosomes
should be circled as a pair.
6. The homologues are independent of one another. They do not pair with each other
at any time during mitosis.
7. D: all of the above
8. A gene is a section of DNA which will code for a particular protein. An allele is an
alternate form of that gene. For example: One allele of the eye color gene codes for
protein which makes eyes brown. Another allele of the eye color gene codes for a
4
protein which makes eyes green. Another example would be the single gene that
contains three different alleles that determine the ABO blood type. Any individual can
receive any two of these three alleles so that a person can be blood type A, B, AB or O.
PART A: (page 4)
1. A. Protein
2. A sister chromatid is one half of a replicated chromosome. A replicated
chromosome contains two identical DNA double strands held together at the
centromere. They are sister chromatids until the centromere breaks, at which point they
become independent daughter chromosomes.
3. The centromere is the site on the replicated chromosome where the two sister
chromatids are attached. It appears as a constriction with two chromosome arms above
and below. The parent strand has replicated along its entire length except at the
centromere.
4. Condensed chromosomes are long pieces of DNA that are highly associated with
and wrapped around protein. Condensation is necessary for nuclear division.
Extended chromosomes are long pieces of DNA that are uncoiled and largely free and
cannot be seen clearly by the naked eye or even with a light microscope.
PART B: (page 5)
1. arose through replication of a parent chromosome.
2. two; two; two; identical
3. There is no pairing of homologous chromosomes during Mitosis. Remind students
that homologous chromosomes pair only during Meiosis so that the chromosome
numbers can be halved to produce the egg and the sperm.
4. 8
5. 92
PART C: (page 7)
1. There are four replicated chromosomes in the Dibble cell, each with two chromatids
held together at the centromere.
2. There would be 46 replicated chromosomes in any human cell undergoing Mitosis
and a total of 92 chromatids.
5
PART D: (page 8)
1. Daughter chromosomes are now unreplicated. Each contains a single DNA
molecule.
2. With the exception of rare mutations, Mitosis leads to the formation of identical
daughter chromosomes.
3. Yes! In fact, each daughter chromosome contains one parent strand of DNA with a
newly synthesized complementary strand.
4. In Mitosis the genetic information in the chromosomes of a cell is first reproduced
precisely and then the duplicate sets of information are distributed precisely to two
daughter cells thus preserving the original genetic blue print.
PART F: (page 10 & 11)
1. The parent cell no longer exists. It has divided into two daughter cells. The
cytoplasm and the other organelles that were in the parent cell have been divided
approximately in half for the two daughter cells.
2. The daughter cells are genetically identical and are similar in size, shape and
function.
3. The daughter cells are identical to the parent cell genetically, but they may be slightly
different in size and shape. This is because cytokinesis (division of the cytoplasm) is not
as precise as Mitosis (division of the nucleus).
4. Two things have been accomplished. Mitosis results in a doubling of cell number
and it also accurately passes along the genetic information to the next generation.
5. Your model of a cell was made of paper; the chromosomes made of yarn and
popsicle sticks are only representations of the real things. This allows you to visualize
and manipulate objects that otherwise can only be seen through a microscope. It is
very important to remember that the real things and processes are quite different from
the models.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
6
Pre/Post Test ANSWER KEY – Mitosis
1. During which phase do chromosomes first become visible? a. Interphase; b.
Telophase; c. Metaphase; d. Prophase
2. A cell with 10 chromosomes undergoes Mitosis. How many daughter cells are
created? Each daughter cell has __________ chromosomes. a. 2, 10; b. 10, 2; c. 1.5;
d. 2, 20
3. What structure is responsible for moving the chromosomes during Mitosis?
a.nucleus; b. centriole; c. spindle fiber; d. cytoplasm
4. Cytokinesis begins in which phase? a. Metaphase; b. Anaphase; c. Prophase
d. Telophase
5. Cell will generally divide when? a. they are 10 hours old; b. they become infected;
c. they become to large; d. they have no food
6. Which phase occurs directly after Metaphase? a. Anaphase; b. Telophase; c.
Prophase; d. Interphase
7. During which phase does the DNA make a copy of itself? a. Prophase; b.
Metaphase; c. Interphase; d. Telophase
8. After replication, each chromosome consists of two: a. centrofibers; b. chromatids;
c. daughter cells; d. centrioles
9. The original cell that undergoes Mitosis is the a. daughter cell; b. sister cell; c.
mother cell; d. parent cell
10. The point at which the sister chromatids are attached is called the: a. Centromere;
b. centriole; c. chromatin body; d. spindle body
11. A cell plate is formed during Mitosis in which of the following? a. sex cell; b. body
cell; c. plant cell; d. animal cell
12. What structure would you not see during Mitosis in an onion root tip? a. cleavage
furrow; b. chromatids; c. cell plate; d. spindle
13. During which phase are the chromosomes lined up along the middle of the cell?
a. Anaphase; b. Prophase; c. Metaphase; d. Interphase
14. Which of the following phases is not actually a phase of Mitosis: a. Interphase; b.
Prophase; c. Metaphase; d. Telophase
15. In which stage of Mitosis does the nuclear membrane “disappear”? a. Interphase;
b. Prophase; c. Anaphase; d. Telophase
16. A cell that has two copies of each chromosome (same number and type) is referred
to as: a. Chromoloid; b. Haploid; c. Monoloid; d. Diploid
17. Mitosis is the process in which what structure divides to form two new identical
ones? a. cytoplasm; b. nuclear membrane; c. nucleus; d. chromosomes
18. What is the best description of homologous chromosomes? A. they are the same
size and shape; b. they contain the same types of genes in the same order; c. they
generally contain different versions (alleles) of many of the same genes; d. all of these
19. What is made by arranging chromosomes from a chromosome spread and
matched into pairs (the largest to the smallest) and assigned numbers? a. karyotype;
b. chromatotype; c. prototype; d. kinetochore
20. During what phase of Mitosis does the nuclear membrane “reappear”?
a. Interphase; b. Prophase; c. Metaphase; d. Telophase
Pre/Post Test – Mitosis
1. During which phase do chromosomes first become visible? a. Interphase; b.
Telophase; c. Metaphase; d. Prophase
2. A cell with 10 chromosomes undergoes Mitosis. How many daughter cells are
created? Each daughter cell has __________ chromosomes. a. 2, 10; b. 10, 2; c. 1.5;
d. 2, 20
3. What structure is responsible for moving the chromosomes during Mitosis?
a.nucleus; b. centriole; c. spindle fiber; d. cytoplasm
4. Cytokinesis begins in which phase? a. Metaphase; b. Anaphase; c. Prophase
d. Telophase
5. Cell will generally divide when? a. they are 10 hours old; b. they become infected;
c. they become to large; d. they have no food
6. Which phase occurs directly after Metaphase? a. Anaphase; b. Telophase; c.
Prophase; d. Interphase
7. During which phase does the DNA make a copy of itself? a. Prophase; b.
Metaphase; c. Interphase; d. Telophase
8. After replication, each chromosome consists of two: a. centrofibers; b. chromatids; c.
daughter cells; d. centrioles
9. The original cell that undergoes Mitosis is the a. daughter cell; b. sister cell; c.
mother cell; d. parent cell
10. The point at which the sister chromatids are attached is called the: a. Centromere;
b. centriole; c. chromatin body; d. spindle body
11. A cell plate is formed during Mitosis in which of the following? a. sex cell; b. body
cell; c. plant cell; d. animal cell
12. What structure would you not see during Mitosis in an onion root tip? a. cleavage
furrow; b. chromatids; c. cell plate; d. spindle
13. During which phase are the chromosomes lined up along the middle of the cell?
a. Anaphase; b. Prophase; c. Metaphase; d. Interphase
14. Which of the following phases is not actually a phase of Mitosis: a. Interphase; b.
Prophase; c. Metaphase; d. Telophase
1
15. In which stage of Mitosis does the nuclear membrane “disappear”? a. Interphase;
b. Prophase; c. Anaphase; d. Telophase
16. A cell that has two copies of each chromosome (same number and type) is referred
to as: a. Chromoloid; b. Haploid; c. Monoloid; d. Diploid
17. Mitosis is the process in which what structure divides to form two new identical
ones? a. cytoplasm; b. nuclear membrane; c. nucleus; d. chromosomes
18. What is the best description of homologous chromosomes? A. they are the same
size and shape; b. they contain the same types of genes in the same order; c. they
generally contain different versions (alleles) of many of the same genes; d. all of these
19. What is made by arranging chromosomes from a chromosome spread and
matched into pairs (the largest to the smallest) and assigned numbers? a. karyotype; b.
chromatotype; c. prototype; d. kinetochore
20. During what phase of Mitosis does the nuclear membrane “reappear”?
a. Interphase; b. Prophase; c. Metaphase; d. Telophase
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter 2013
2
10X Magnification of Stained Human Cheek Cells
Parts of the Human Cheek Cell at 40X Magnification
Can you name these parts of the Human Cheek Cell?
CELL CYCLE
During Interphase DNA replicates which must occur before Mitosis can begin .
Centrioles
: Nuclear division
View of onion root tip under low power
MITOSIS – ONION ROOT TIP
Interphase
Prophase
Early Anaphase
Anaphase
Later Prophase
Telophase
Metaphase
Later Telophase
STAGES OF MITOSIS IN WHITEFISH BLASTULA
Interphase
This cell is shown, as this is how all cells look before mitosis. Please be aware that Interphase is a phase of the cell cycle, but NOT a stage of mitosis. Mitosis ‐ Early Prophase To begin mitosis, the nuclear membrane breaks down, while the chromosomes shorten and thicken (here, a chromosome is two chromatids, bound at a point called the centromere, making an "X" shape). The other structures important for mitosis are also forming (i.e. the centrioles). Mitosis ‐ Metaphase The spindle has now formed and the nuclear membrane has broken down. The chromosomes are lined up along the cell's center and are attached to the spindle fibers. When the individual chromatids (½ of the "X") are separated from the chromosome (the "X"), they are now each referred to as a chromosome (i.e. In metaphase, the chromosome, composed of two chromatids, separates into the individual chromatids, which are then renamed chromosomes).
Mitosis ‐ Anaphase The newly formed chromosomes are pulled along the spindle toward opposite poles of the cell. Mitosis ‐ Telophase The chromosomes have finished their migration to the poles. The spindle has broken down and disappeared. The cell membrane pinches in (forms a cleavage furrow) along the center creating two separate cells . At this time, the chromosomes uncoil and become less visible (as they are during Interphase), the nuclear membrane reforms. The division of the cytoplasm is called cytokinesis. The division of the nucleus is Mitosis. At the end of Telophase, the cell reenters Interphase.
The X is pointing to what structure?
What is this???? Stay tuned for another activity.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
Name ______________________________
The Human Cheek Cell
1. List the 3 parts of the Cell Theory
2. Describe or define each of the following
--cell membrane
--cytoplasm
--nucleus
--organelle
Procedure:
1. Gently scrape the inside of your cheek with the flat
side of a toothpick. Scrape lightly. DO NOT DIG
INTO YOUR CHEEK TISSUE.
2. Put a drop of water on a slide. Carefully smear the
cells by gently rubbing the toothpick across the slide.
Put a drop of methylene blue on a slide. CAUTION:
methylene blue will stain clothes and skin.
3. Stir the end of the toothpick in the stain and throw
the toothpick away.
4. Place a coverslip onto the slide
5. Use the low power objective to focus. Cells should
be visible, but they will be small and look like nearly
clear purplish blobs. If you are looking at something
very dark purple, it is probably not a cell
6. Once you think you have located a cell, switch to
high power and refocus. (Remember, do NOT use
the coarse adjustment knob at this point)
3. Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell
membrane. Draw your cells to scale.
Low Power
High Power
4. Why is methylene blue necessary?
5. The light microscope used in the lab is not powerful enough to view other organelles in the
cheek cell. What parts of the cell were visible?
6. List 2 organelles that were NOT visible but should have been in the cheek cell.
7. Is the cheek cell a eukaryote or prokaryote?
How do you know?
8. Keeping in mind that the mouth is the first site of chemical digestion in a human. Your saliva
starts the process of breaking down the food you eat. Keeping this in mind, what organelle do
you think would be numerous inside the cells of your mouth?
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter 2013
The Human Cheek Cell : KEY
1. List the 3 parts of the Cell Theory:
All living things are made of cells
Cells can only come from other cells
Cells are the basic unit of structure and function
2. Describe or define each of the following:
Cell membrane: Outer boundary of the cell
Cytoplasm: Fluid within the cell
Nucleus: Control center of the cell
Organelle: Cell structure that has a specific function
3. Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane of
a single cell. Draw your cell to scale.
Low power should have cells that are fairly small within the viewing field; at high power a
cheek cell will take up about half of the viewing field.
4. Why is methylene blue necessary?
Because cells are transparent, methylene blue stain is necessary to make the cell parts
visible.
5. The light microscope used in the lab is not powerful enough to view other organelles in the
cheek cell. What parts of the cell are visible?
Nucleus and cell membrane.
6. List two organelles that were NOT visible but should have been in the cheek cell.
Mitochondria or lysosome or endoplasmic reticulum.
7. Is the cheek cell a eukaryote or prokaryote?
How do you know?
Eukaryote. It has a nucleus.
8. The mouth is the first site of chemical digestion in a human being. Your saliva starts the
process of breaking down the food you eat. Keeping this in mind, what organelle do you think
would be numerous inside the cells of your mouth?
Lysosomes.
Cut n’ Paste Karyotyping Activity
Cut out chromosomes here
http://gslc.genetics.utah.edu
Paste chromosomes here with their match
Genetic Science Learning Center, 15 North 2030 East, Salt Lake City, UT 84112
© 2003 University of Utah
Cut n’ Paste Karyotyping Activity
Completed Karyotype
http://gslc.genetics.utah.edu
Genetic Science Learning Center, 15 North 2030 East, Salt Lake City, UT 84112
© 2003 University of Utah
Cut n’ Karyotyping Activity – Part A
Cut each chromosome from Part A and tape it to its matching chromosome on Part B.
Tape the cut chromosome on the right side of its matching partner in Part B.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
KARYOTYPING ACTIVITY – PART B
Cut n’
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
Daughter
Cell
Telophase
Metaphase
parent cell
last phase
line up
diploid
divide
2nd phase
Anaphase
Prophase
Interphase
separate
1st phase
resting phase
condensed
chromosomes
cell cycle
rd
3
phase
Haploid
Zygote
meiosis
gametes
gametes
embryo
Gene
Allele
inherited
DNA
chromosome
chromosome
Spindle
fibers
Centrioles
move
spindle fibers
cell division
Opposite
poles
Telophase
Metaphase
Last phase
Divide
Line up
2nd Phase
Prophase
1st Phase
Condensed
chromosomes
Interphase
Resting phase
Cell cycle
Mitosis
Meiosis
Fertilization
body cells
haploid
gamete
diploid
gamete
embryo
Cell cycle
Replication
Cytokinesis
daughter cells
chromosome
cell plate
mitosis
mitosis
divide
Chromosome
Sister
chromatids
Homologous
chromosomes
nucleus
exact copy
pair
many genes
chromosome
meiosis
Diploid
Haploid
Zygote
mitosis
meiosis
gametes
double
gametes
embryo
Gamete
Gene
Allele
sperm
inherited
DNA
egg
chromosome
chromosome
Centromere
Spindle
fibers
Centrioles
chromosome
move
spindle fibers
mitosis
cell division
Opposite
poles
Teacher Notes for Mitosis, Meiosis and Fertilization Vocabulary Review Game
In this version of the Taboo Game, each group of 3-5 students receives a deck of 18
cards, face down. One student takes the top card and gives clues to help the other
students guess the target word in the black box on the top of the card. In giving clues,
the student may not use the two taboo words listed below the target word. These taboo
words have been chosen to help students remember the meaning of the target word,
while still providing sufficient vocabulary choices for the student to give the biological
clues needed for the other students in the group to guess the target word. Students
should be instructed to use only biological clues (e.g. no "sounds like" or references to
popular culture). The person who guesses the target word correctly gets the card and
takes the next card from the deck to give clues to the other students. Once the deck is
completed the student with the most cards is the winner. Alternatively, two students can
play together and there will not be a winner (or loser).
To prepare a deck for 3-5 students, photocopy both pages in the game file and cut nine
cards per page. We recommend making each deck on a different color heavy paper or
poster board, so you can easily identify which cards belong in which deck. If you are
printing on white paper, you may want to identify the cards in each deck by using a
different color marker to make stripes down the outside edges of each deck.
The file for the game cards is a Word document, so you can easily add, delete or
change the vocabulary to match the vocabulary you want your students to learn. You
may also want to combine this cell division deck with the deck for the Genetics
Vocabulary Review Game; if you do this you should be aware that the target words
gene and allele appear in both decks.
Student Lab Guide 1:
Mr. Dibble
Introduction and Instructions for Modeling Mitosis
Study mitosis in the cells of Mr. Dudley Dibble, an imaginary creature with four
chromosomes which are represented at different phases of mitosis by red and blue yarn
and large red and blue popsicle sticks. Work out each step of the process using bulletin
board paper for the cells and yarn for the cell membrane, nuclear membrane and
spindle fibers.
Go through the entire modeling process several times. Each group member takes a
turn as the “explainer”. Follow along with the steps below for the first one or two turns
and then follow them from memory. Answer the questions about each stage as you go
along and answer them each time you go through the process. Explain your answers in
your own words.
A. Introduction: Interphase and Chromosome Replication
1. Lay out on a table the bulletin board paper which represents a cell.
2. Tape the piece of black yarn to the paper in an oval shape to form the cell
membrane.
3. Tape the piece of purple yarn to the paper to form the nuclear membrane.
Throughout Interphase the chromosomes are extended and are NOT visible in the light
microscope. (Figure 1) The DNA is uncoiled and uncondensed. These will be
simulated with two pieces of red and two pieces of blue yarn.
4. Place two 12 inch pieces of red yarn and two 12 inch pieces of blue yarn inside the
nucleus of the cell. These pieces of yarn should be intertwined at this phase.
1
FIGURE 1: Dibble Uncondensed Chromosomes
Uncoiled, uncondensed chromosomes
Cell Membrane
Nuclear Membrane
5. Prior to mitosis the chromosomes begin to coil up and condense which makes them
shorter and thicker and become visible. To represent this, cut the red yarn and the blue
yarn into 6 inch pieces. Place two pieces of the red yarn and two pieces of the blue
yarn back into the nucleus. This represents a diploid cell with two pairs of
chromosomes (Figure 2). At this point the chromosomes have NOT replicated.
FIGURE 2: Dibble Diploid Chromosome Set
Chromosomes
Cell Membrane
Nuclear Membrane
Answer the following questions:
1. What does diploid mean?
2. Are most human cells diploid?
3. Define homologous chromosomes.
2
4. How many pairs of homologous chromosomes are present in the picture of the
Dibble cell above?
5. Draw a circle around each homologous pair of chromosomes in Fig. 2.
6. Are the homologues (a short name for homologous chromosomes) above paired with
one another in the cell or are they independent from one another?
7. What is the best description of homologues: a. they are the same size and shape; b.
they contain the same types of genes in the same order; c. they generally contain
different versions (alleles) of many of their genes; d. all of the above.
8. Contrast gene and allele.
During Interphase the DNA molecules replicate. This creates an exact copy
of each chromosome.
FIGURE 3: CHROMATID
Original chromosome
Replicated chromosome
Centromere
FIGURE 4: INTERPHASE CHROMOSOMES REPLICATED
Cell Membrane
Chromosomes
Nuclear Membrane
The nucleus initially contained four unreplicated chromosomes (two pieces of red yarn
and two pieces of blue yarn). During Interphase each chromosome makes an identical
copy of itself. The two identical chromosomes (sister chromatids) are attached at the
point called the centromere. (Figure 3) Represent the chromosome replication by
placing the two additional 6 inch pieces of the red yarn and the two additional 6 inch
pieces of the blue yarn in the nucleus. Use tape (representing the centromere) to attach
the sister chromatids. Now it contains four replicated chromosomes (four red pieces of
yarn and four blue pieces of yarn). (Figure 4)
3
Answer the following questions:
1. A chromatid is made of DNA and which of the following: a. protein; b. carbohydrate;
c. lipid.
2. How do the sister chromatids differ from the chromosomes?
3. What is a centromere?
4. Contrast condensed (coiled) and extended (uncoiled) chromosomes.
B: PROPHASE: First Stage of Mitosis
1. Replace the red and blue yarn with two pair of red popsicle sticks held together by
rubber bands and two pair of blue popsicle sticks held together by rubber bands. This
represents replicated chromosomes condensed and visible held together at the
centromere (the rubber band represents the centromere).
2. In this phase the nuclear membrane disappears which allows the rest of the mitotic
events to occur. Remove the purple yarn that represents the nuclear membrane (put
aside for use later).
3. At each of the opposite sides of the cell, tape a green rectangular structure which
represents the two centrioles which are at right angles to each other.
4. Attach six pieces of the rust yarn (representing the spindle fibers) with tape across
the cell from one centriole to the other. Some of the spindle fibers attach to the
replicated chromosomes at their centromeres. Place each of the four pairs of replicated
chromosomes on a separate spindle fiber (Figure 5).
FIGURE 5: PROPHASE
Centrioles
Cell Membrane
Spindle Fibers
4
Answer the following questions:
1. Are the two sister chromatids that are connected by a centromere identical to one
another or do they contain different alleles? Explain.
2. As noted above, these structures are called replicated chromosomes. Replicated
chromosomes are quite different from the unreplicated chromosomes seen earlier.
Compare replicated chromosomes to unreplicated ones by filling in the blanks below:
The amount of DNA in a replicated chromosome is ________ times the amount of DNA
in an unreplicated chromosome.
The number of copies of each gene in a replicated chromosome is _______ times the
number of copies in an unreplicated chromosome.
Each replicated chromosome contains _________ (number) of complete copies of
genetic information.
The copies of genetic information in each chromosome are: a. identical; b.
homologous; c. complementary.
3. Do you think that the homologous replicated chromosomes (the two pairs of blue/red
popsicle sticks) will pair with one another during mitosis? Explain.
4. How many sister chromatids are in your Dibble nucleus during Prophase?
5. A diploid human cell contains 46 unreplicated chromosomes in early Interphase.
How many sister chromatids will be present in the human cell during Prophase of
mitosis?
5
C. METAPHASE: Second Stage of Mitosis
Figure 6: Metaphase
Metaphase plane
Centrioles
Spindle Fiber
1. Arrange your Dibble chromosomes (pairs of red and blue popsicle sticks) across the
center of the cell. (Figure 6)
Figure 7: Orientation of chromosomes
The specific order of chromosomes and their orientation (right side up, upside down) is
completely random.(Figure 7) In metaphase, replicated chromosomes are lined up on
the metaphase plane (across the center of the cell) by the spindle fibers. (Figure 6)
Homologous chromosomes are independent of one another. Homologous replicated
chromosomes, such as the two sets of red or blue popsicle sticks, are NOT PAIRED.
6
Answer the following questions:
1. How many replicated chromosomes are on the metaphase plane in Dibble?
2. How many replicated chromosomes would be on the metaphase plane in a human
cell undergoing mitosis?
D. ANAPHASE: Third Stage of Mitosis
1. Remove the rubber bands and separate the popsicle sticks (sister chromatids) to
form daughter chromosomes. (Figure 8)
2. Cut the spindle fibers in half.
3. Daughter chromosomes are moved toward opposite poles by the spindle fibers in
Anaphase. They are pulled through the cytoplasm at the centromere.
Figure 8: Anaphase
Chromosomes
Cell Membrane
Centriole
Centriole
Spindle Fiber
7
Answer the following questions:
1. Are the daughter chromosomes replicated or unreplicated?
2. Are the two sets of daughter chromosomes, the one moving toward the left and the
other toward the right, identical or non-identical?
3. Are the two sets of daughter chromosomes identical to those in the parent cell?
4. What is accomplished by this process?
E. TELEPHASE: The Last Stage of Mitosis
1. The spindle fibers disappear. Remove the rust yarn (spindle fibers) from your cell.
2. Daughter chromosomes (red and blue popsicle sticks) reach the poles (opposite
sides) of the cell. The daughter chromosomes start to uncoil and become extended.
Replace red and blue popsicle sticks with 6 inch pieces of red and blue yarn (uncoiled
chromosomes).
3. Two new nuclear membranes form; one around each set of daughter chromosomes
(red and blue yarn). Cut the purple yarn in half to create the two new nuclear
membranes in your cell. (Figure 9)
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4. In animal cells the cell membrane (black yarn) will begin to pinch in, starting a
division in the cytoplasm. (Figure 9)
Figure 9: Telophase
Cell Membrane
Nuclear Membrane
Chromosomes
Cleavage Furrow
F. Cytokinesis: Cell Division; Two Daughter Cells Formed
1. The cytoplasm of an animal cell pinches in half at the center (Figure 9) from the
outside in, until it has produced two separate daughter cells (Figure 10). Divide your
cell in half in this manner by replacing the long black yarn. Cut the black yarn which
represented the parent cell membrane into two equal pieces. These two shorter pieces
of black yarn represent the membranes of the two NEW daughter cells. Use the
purple yarn from the previous cells to make the two new nuclear membranes. (Figure
10)
Figure 10: Cytokinesis Completed; Two Daughter Cells
Cell Membrane
Nuclear Membrane
Chromosomes
Cell Membrane
Chromosomes
Nuclear Membrane
9
2. The daughter cells are now entering the early Interphase Stage. Your Dibble
chromosomes are continuing to uncoil and become less condensed. Replace the two
red and blue 6 inch pieces of yarn with two red and blue 12 inch pieces of yarn.
Intertwine the red and blue pieces. This represents the daughter cells entering a new
Cell Cycle. The cells will grow to full size and, if continuing to divide, will replicate the
Dibble chromosomes and will repeat the cycle again. (Figure 11)
Figure 11: Early Interphase
Nuclear Membrane
Cell Membrane
Chromosomes
Answer the following questions:
1. Does the parent cell still exist?
2. How are these daughter cells related to one another?
3. How are these daughter cells related to the parent cell?
4. Overall, what has been accomplished by mitosis?
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5. You have used your materials to model mitosis (nuclear division) and cellular
division. Explain some ways in which a model (like you used) differs from the actual
things and processes it represents.
PRACTICE
As you noted above, you should go through the entire process several times with each
group member taking a turn as the “explainer”. Follow along with the procedures in the
Student Lab Handout for the first one or two turns, and then go through two or more
repetitions from memory. You may also refer to Table 1 below for a rough guide. Your
teammates can assist you by asking questions and giving hints.
TABLE 1
Interphase
G1 Stage:
Growth & development of
the cell
Protein synthesis
S-phase:
Chromosomes replicate
(DNA makes an exact copy
of itself)
G 2 Stage:
Growth and development
Organelle replication
Mitosis
Prophase:
Replicated chromosomes
condense
Nuclear membrane
dissolves
Spindle fibers form
Metaphase:
Replicated chromosomes
line up across the center of
the cell
Anaphase:
Sister chromatids separate
Daughter chromosomes
move to opposite poles
Telophase:
Cytoplasm begins to
separate
New nuclear membranes
form
Spindle fibers disappear
Cytokinesis
Complete cell division
occurs
Produces two daughter
cells
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
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STUDENT LAB GUIDE 2: Mitosis Observation
In the spaces provided below, on the basis of your observations of the
prepared slides of mitosis, draw and identify any one of the stages in the
onion root tip and the whitefish blastula. Use the lines underneath each
drawing to record notes about what is happening during the stage you
chose.
Plant Cell: Onion Root Tip
Animal Cell: Whitefish Blastula
Stage: ___________________
Stage: ___________________
Observations:
Observations:
__________________________
__________________________
__________________________
__________________________
__________________________
__________________________
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter 2013