Download Name - Mrs. GM Biology 300

Name: _______________________
Mrs. G-M (Bio)
Date __________
Period _________
Mitosis Modeling (string & paper) “mini-lab”
Your body carries out two different kinds of nuclear division (or cellular reproduction). The
first type of nuclear division (or cellular reproduction) is called mitosis. Mitosis results in the
formation of two new “daughter” cells from one parent cell. The new “daughter” cells are
genetically identical to each other and to the “parent” cell; this is important because mitosis
makes new somatic (body) cells for growth and repair.
We will talk about the second type of nuclear division (or cellular reproduction), meiosis, later.
Materials:

8 “chromosomes” (2 long pink, 2 short pink, 2 long blue, 2 short blue) with small pieces of
Velcro attached to the center (so that the two "sister chromatids" can be attached to each
other)

1 large piece of string to represent the cell membrane

textbook, notes, and/or the internet as reference

colored pencils (pink and blue)
Purpose:
Chromosomes are present inside the nucleus, but usually cannot be seen. In this lab, you will
model mitosis on a larger scale using paper cutouts to represent chromosomes and a string to
represent the cell membrane. A cell may contain many chromosomes, but in this model, you will
use only 4 chromosomes to help simplify the process. We are also NOT showing the nucleus.
Procedure for Interphase before replication (before mitosis):
1. Make a circle with the string to represent the membrane around your “cell”.
2. Place a long pink, a long blue, a short pink, and a short blue chromosome into the “cell”.
3. To the right, sketch (in color) what your “cell” looks like.
4. Answer the following questions before moving on to the next step.
a. What is the total number of (single-stranded) chromosomes present in this cell before
mitosis? _______
b. How many long (single-stranded) chromosomes are present before mitosis?
________________
c. How many short (single-stranded) chromosomes are present before mitosis?
_______________
Procedure for Interphase after replication (before mitosis)/Prophase (step 1 of mitosis):
In interphase, before the cell begins mitosis, each chromosome makes and exact copy of itself
and becomes double-stranded. This process is called replication. Each strand of a doublestranded chromosome is called a sister chromatid. It is during Prophase that these doublestranded chromosomes first become visible.
5. To show chromosome replication, use the remaining paper chromosomes, and match them
with the original chromosomes that are already in your “cell” by crossing them to make an
“X” (to represent a double-stranded chromosome). The two “strands” of the double-stranded
chromosome are the sister chromatids which are held together by a snap-like “centromere”.
6. To the right, sketch (in color) what your “cell” looks like.
7. Answer the following questions before moving on to the next step.
a. What is the total number of (double-stranded) chromosomes present in this cell at the
end of Prophase? _______
b. How many long (double-stranded) chromosomes are present at the end of Prophase?
________________
c. How many short (double-stranded) chromosomes are present at the end of Prophase?
_______________
Procedure for Metaphase:
During mitosis, the double-stranded chromosomes line up along the cell’s center.
8. Line your double-stranded chromosomes up along the center of the “cell”. (single-file from
top to bottom).
9. To the right, sketch (in color) what your “cell” looks like.
10. Answer the following questions before moving on to the next step.
a. What is the total number of (double-stranded) chromosomes present in this cell at the
end of Metaphase? _______
b. How many long (double-stranded) chromosomes are present at the end of Metaphase?
________________
c. How many short (double-stranded) chromosomes are present at the end of Metaphase?
______________
Procedure for Anaphase:
During Anaphase, the two sister chromatids "unsnap" and separate. The chromatids (singlestrands) are pulled toward opposite ends (poles) of the cell by the spindle fibers (and centrioles
in animal cells). During this phase, the chromosome number is temporarily doubled.
11. To represent this, separate your sister chromatids by moving one chromatid (from each
double-stranded chromosome) to the left side of each cell and the other to the right side of
each cell.
12. To the right, sketch (in color) what your “cell” looks like.
13. Answer the following questions before moving on to the next step.
a. What is the total number of (single-stranded) chromosomes present in this cell at the
end of Anaphase? _______
b. How many long (single-stranded) chromosomes are present at the end of Anaphase?
________________
c. How many short (single-stranded) chromosomes are present at the end of Anaphase?
______________
Procedure for Telophase (the last step in mitosis) and Cytokinesis (after mitosis):
During Telophase, the single-stranded chromosomes arrive at the poles, nuclear membranes
form around each set of chromosomes (forming two new nuclei), and the cell membrane pinches
in and eventually fully separates forming two new “daughter” cells (cytokinesis) .
14. To represent the formation of the two new “daughter” cells, pinch the string down in the
center, forming two circles to represent the new “daughter” cells.
15. To the right, sketch (in color) what your “cells” look like now.
16. Answer the following questions before moving on to the next step.
a. What is the total number of chromosomes present in each cell at the end of
Telophase/Cytokinesis? _______ & _______
b. How many long chromosomes are present in each cell at the end of
Telophase/Cytokinesis? ____________ & _____________
c. How many short chromosomes are present in each cell at the end of
Telophase/Cytokinesis? _______________ & _____________
General Analysis and Conclusion Questions:
1. Sketch the parent cell from the beginning of the lab (during interphase before replication).
2. Sketch each daughter cell from the end of the lab (after telophase/cytokinesis).
3. At the start of the lab:
a. How many chromosomes did the parent cell have? _________________________
b. Is the parent cell diploid or haploid? __________________________________
4. At the end of the lab:
a. How many chromosomes did each daughter cell have? ______________________
b. Is each daughter cell diploid or haploid? _______________________________
5. At the start of the lab:
a. How many long chromosomes did the parent cell have? _____________________
b. How many short chromosomes did the parent cell have? ____________________
6. At the end of the lab:
a. How many long chromosomes did each daughter cell have? __________________
b. How many short chromosomes did each daughter cell have? _________________
c. Is this the same as or different from the parent cell? _____________________
i. Why is this important?
7. LOOK AT THE CHROMOSOME COMBINATIONS (LENGTH AND COLOR) in your sketches
of the parent cell during interphase (in question 1) and each of the two daughter cells after
telophase/cytokinesis (in question 2).
a. Are the chromosome combinations (length and color) in the parent and each of the
two daughter cells exactly the same or different? ________________________
i. Why is this important?
b. Are the chromosome combinations (length and color) in each of the two daughter
cells exactly the same or different? __________________________________
i. Why is this important?