Chapter 12&13
Handouts
Mitosis and Meiosis
Bio 2
Materials compiled by Mrs. Mikkelson
Name __________________
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Mitosis Vocabulary
Define the term and explain its function in mitosis
1.
chromatin
2.
chromosome
3.
chromatid
4.
centromere
5.
kinetochore
6.
kinase
7.
cyclin
8.
centriole
9.
centrosome
10.
cleavage furrow
11.
cell plate
12.
spindle fibers
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THE CELL CYCLE and MITOSIS
Before a cell of a plant, animal, or another eukaryotic organism reproduces, it undergoes mitosis or
meiosis.
Multicelled organisms grow by way of mitosis and the cytoplasmic division of body cells
(CYTOKINESIS). On the other hand, meiosis occurs only in germ cells, which are set aside for the
formation of gametes (sperm and egg). Sexual Reproduction by meiosis allows for species survival and it
increases genetic variability.
Before a cells prepares for mitosis, its DNA molecules are stretched out like threads. Each DNA molecule
with it's proteins is a chromosome. That one protein contributes to a trait (gene) that is inherited. Each
person has 46 chromosomes. 23 from the mother, 23 from the father.
Each time new cells are produced, there is a cycle it must go through. They are:

Interphase (before mitosis)

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis
" Intelligent People Meet At Three O'Clock"
CELL AT INTERPHASE
Keep in mind, Interphase is NOT a part of mitosis. Interphase is the Longest phase in the Cell Cycle of a
typical cell. Interphase use to be referred to as the "Resting Phase". Interphase is where the cell grows,
develops into a mature functioning cell before the DNA is duplicated, then the DNA is duplicated, and
lastly, prepares for division.
Interphase can be divided into Three Phases:
1. G1 Phase - Period of normal metabolic cellular activities; the number of organelles and amount
of cytoplasm in a the cell increase.
2. S Phase - The Genetic Material (DNA) is duplicated. The Chromosomes of the cell Replicate.
3. G2 Phase - Structures directly involved with mitosis are formed.
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A CELL DURING PROPHASE THE FIRST PHASE OF MITOSIS
During Prophase, the CHROMATIN condenses into CHROMOSOMES of TWO SISTER
CHROMATIDS joined together by the CENTROMERE. The nuclear envelope starts to break up and the
Nucleolus disappears.
A CELL DURING METAPHASE
During Metaphase, the Chromosomes are line up at the equator or center of the cell (Equatorial Plane) by
the spindle fibers attached to the Centromeres. The two sister chromatids are attached to spindle fibers from
opposite ends of the cell.
A CELL DURING ANAPHASE
During Anaphase, two sister chromatids of each chromosome break and are now separate chromosomes
that move to opposite spindle poles. The Sister Chromatids are thus separated from each other.
A CELL DURING TELOPHASE
Lastly, in Telophase, the chromosomes decondense. New patches of membrane fuse to form new nuclear
envelopes around them.
THE PROCESS OF MITOSIS IS NOW COMPLETE. THE CELL MEMBRANE BEGINS TO PINCH
(CLEAVAGE FURROW) THE CELL IN TWO AS CYTOKINESIS BEGINS.
MITOSIS IS THE PROCESS BY WHICH A NUCLEUS GIVES RISE TO TWO IDENTICAL NUCLEI.
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DURING CYTOKINESIS, THE CYTOPLASM OF A CELL AND ITS ORGANELLES SEPARATE
INTO TWO NEW DAUGHTER CELLS.
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6
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MITOSIS TIME LAB
Name__________________________
Mitosis is considered nuclear division, since its main stages deal strictly with the nucleus and its contents
(DNA). Mitosis consists of 4 major stages: Prophase, Metaphase, Anaphase, and Telophase. Mitosis is part
of a larger process called the cell cycle. When a living organism needs new cells to repair damage, grow, or
just maintain its condition, cells undergo the cell cycle. In this lab you are going to determine the
approximate time it takes for a cell to pass through each of the four stages of mitosis. You may use your
textbook and class notes to help you identify the stages of mitosis as seen under the microscope.
Materials:
Microscope or magnifying glass
Prepared slide (Onion root tip)
Lab Paper
Procedure:
1. Set up a compound light microscope and turn on the light ( if microscope not available use pictures
below ).
2. Place a slide containing a stained preparation of the onion root tip.
3. Locate the meristematic zone, which is just above the root cap at the very end of the tip.
4. Focus in on low power and then switch to medium or high power. Below find micrographs of the four
stages of mitosis. Use them to help you identify the stages on the microscope slide.
Anaphase
Prophase
Metaphase
Telophase
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5. Now count the number of cells found in each stage of mitosis and place the data in the chart below.
6. Determine the percentage of time each cell will spend in each stage of mitosis. Divide the number of
each cell by the total number of cells and multiply by 100 to determine the percentage. COPY THIS
CHART IYNB. Answer the Questions IYNB.
Stage of Mitosis
Number of Cells
Percent of time in each
stage
Prophase
____________________________________________
_____________%
Metaphase
____________________________________________
_____________%
Anaphase
____________________________________________
_____________%
Telophase
____________________________________________
_____________%
Total number of
Cells
____________________________________________
100%
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QUESTIONS
1. Of the four stages of mitosis, which one takes the most time to complete? __________________
2. Which is the shortest stage in duration? ____________________.
1.
Might these percentages be inaccurate? Explain at least three ways
you could make them more accurate.
2.
What would happen if the process of mitosis skipped metaphase?
3.
Which stage was the most numerous on the slide? How can you explain this observation?
4.
Did each stage have the same appearance in all the examples you observed? Explain.
5.
What are the main features of telophase?
6.
What is happening in anaphase that makes it appear different from metaphase?
7.
Why is the root tip a good place to observe mitosis?
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Biology II
Play-by-Play
Scoring Rubric
Phases: Describe what is occurring: Organelles involved, chromosome position, key
phase. 20 points total

Prophase
5

3
2
1
4
3
2
1
4
3
2
1
4
3
2
1
Anaphase
5

4
Metaphase
5

features of each
Telophase
5
Presentation: Follow instructions, address phases in the correct order, overall quality of work is good. 5
points total
5
4
3
2
1
Total:___/25
Scored by_________________________
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TWO THINGS LEAD TO GENETIC RECOMBINATION, THE PRODUCING OF A NEW GENETIC MIXTURE,
DURING MEIOSIS:
THE FIRST IS CALLED INDEPENDENT ASSORTMENT, WHICH IS THE RANDOM SEPARATION OF
HOMOLOGOUS CHROMOSOMES DURING MEIOSIS I.
THE SECOND IS PICTURE BELOW AND IS CALLED CROSSING OVER, WHICH OCURRS DURING PROPHASE
I OF MEIOSIS DURING THE SYNAPSIS, AND FORMING OF TETRADS.
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Meiosis Play of Science
Act 1: Synthesis
Chromatid 1 – (to chromatid 2) Look at how good we are. Wouldn’t this cell be better
if there were more of us around?
Chromatid 2 – Of course it would! We are DNA, so we run this cell. There should be
more of us around.
Chromatid 1 and 2 - LET’S REPLICATE!! (chromatids join with their copies)
Act 2: Meiosis I
Centriole 1 – Those chromosomes think they are so special. Lets see how tough they are
if we split their number in half.
Centriole 2 – Yeah! Divide and conquer baby! Our spindle fibers should do the trick.
Centriole 1 – You go to that end of the cell and I’ll go to this one.
Chromatid 3 and copy – Hey, things seem to be changing around here.
Chromatid 4 and copy – What do you mean?
Chromatid 3 and copy – Well, our nuclear membrane seems to be breaking up, and
those centrioles are suspiciously moving to both ends of our cell.
Chromatid 4 and copy – I see what you mean. I’ll warn the others. (turn to all the
chromatids) Hey everyone! Something is going down. I think we should pair up
just to be safe.
Chromatid 1 and copy – I’ve seen the changes too. But how should we pair up?
Chromatid 2 and copy – I know! Pair off with the chromosome that is the same size
and shape as you and it should have similar genes on the same area as you.
Chromatid 3 and copy – Those centrioles are at both poles now. Lets all get to the
middle of the cell. Stay with your homologous pair!
Centriole 1 and 2 – Spindle fibers go get a chromosome!
Spindle 1 – (looking confused) How are we supposed to get the chromosomes?
Spindle 2 – Don’t worry. Just go to the kinetochore. They love us!
Spindle 3 – Yeah, they’ll eat us up.
Spindle 4 – Remember, we have to get the whole chromosome, not just a chromatid.
(spindles attach to kinetochores)
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Spindle 5 (to spindle 6 looking sad) – Hey spindle, you look a little down. What’s
wrong?
Spindle 6 – I had a mitosis job once. It was a lot better than this.
Spindle 5 – Really? How was it different?
Spindle 6 – It was much easier. We could split the chromosomes apart and just take a
chromatid
(now the chromosomes are at the poles)
Spindle 7 (to spindle 8) – I don’t know if this was such a good job.
Spindle 8 – Why do you say that?
Spindle 7 – Don’t you see what’s going on here? Look at that cleavage furrow. These
cells are about to split)
(other spindles leave the cell – go behind the desk)
Spindle 8 – I see what you mean. Hey! Where did the rest of our spindle buddies go?
What’s going to happen to us?
Spindle 7 – They’re gone pal, and so are we, but don’t worry we’ll be back soon.
Chromatid 1 and copy – I can’t believe we lost our homologous pair.
Chromatid 2 and copy – I know what you mean. It seems like we have only half of our
genetic material.
Chromatid 1 and copy – I feel like such a haploid.
Chromatid 3 and copy (sarcastically) – Wow, great idea! Line up in the middle. It’s all
my fault.
Chromatid 4 and copy – Don’t feel so bad. At least we still have our exact copy of
ourselves.
Centriole 1 (talking to him/herself) – Well the plan worked, we divided the cell.
Centriole 2 (talking to him/herself) – We showed those chromosomes a thing or two, but I’ve got a feeling
this won’t be the last division.
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Biology 2
Meiosis Tutorial
Name___________________
Instructions:
1. Go to the website: http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/main.html
2. Click on “Reproduction,” read and take notes on this and the next three pages.
3. Discuss the concepts with a partner.
4. Do the test questions, “Test Yourself,” as a quiz. Keep your own score.
5. You may use any notes that you took on the previous pages to answer the quiz questions.
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Mitosis/Meiosis Comparison Simulation
Materials:
16 pipe cleaners
2 pieces of paper
Procedure:
You will be working in groups of two for this activity. First, fold one of the pieces of paper in half. This
will represent a cell going through mitosis. Fold the other piece of paper in quarters. This paper will be
your cell that is dividing through meiosis.
Using the pipe cleaners (chromosomes), you should manipulate the contents of your cells to indicate what
happens in both mitosis and meiosis. After about 15 minutes, one group will be randomly selected to
demonstrate and explain their simulation to the rest of the class.
After the simulation, complete the following chart comparing mitosis and meiosis.
mitosis
meiosis
# of parent cells
Type of reproduction
# of cell divisions
# of daughter cells produced
# of chromosomes in daughter
cells compared to parent cell
Haploid or diploid # produced in
daughter cells
Genetic similarity between parent
and daughter cells
Importance in the animal body
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Name __________________
Meiosis Review Worksheet
1. Make a chart of the differences between mitosis and meiosis
2. When and how can sister chromatids become non-identical?
3. Why is it important to have genetic variance from one generation to the next?
4. Why is it important that the primary oocyte does not divide equally in the process of meiosis?
5. If the diploid number of a cell is 10, draw metaphase I, then draw metaphase II. Be sure to label
your drawings.
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Mitosis & Meiosis Test Ready
1. Know the similarities and differences between prokaryotic and eukaryotic cell division
2. Know what occurs at the three stages of interphase
3. Understand how the cell cycle is controlled
4. Know the order of the phases of mitosis
5. Know the distinguishing characteristics of each phase
6. Be able to identify the phases of mitosis under the microscope
7. Know the purpose of mitosis
8. Be able to compare and contrast mitosis and meiosis
9. Know the order of the phases of meiosis
10. Know the distinguishing characteristics of each phase of meiosis
11. Know the purpose of meiosis
12. Be able to compare and contrast spermatogenesis and oogenesis
13. Understand how meiosis gives us genetic variation and why that is important
Vocabulary:
 Chromosomes
 Chromatid
 Chromatin
 Centromere
 Kinetochore
 Kinase
 Cyclin
 Centriole
 Centrosome
 Cell plate
 Spindle fibers
 Diploid
 Haploid
 Gamete
 Synapsis
 Bivalent
 Crossing over
 Zygote
 Fertilization
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