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Mitosis and Meiosis
Mitosis
Classwork
1. Identify two differences between meiosis and mitosis.
2. Provide an example of a type of cell in the human body that would undergo
mitosis.
3. Does cell division occur during interphase? Explain your answer.
4. Explain what occurs in the ‘S’ portion of interphase. Why is the ‘S’ sub-phase
essential in preparation for mitosis.
5. In what way is the preparation that occurs during the ‘G1’ phase similar to what
occurs during the ‘S’ phase.
6. Explain the importance of cytokinesis to the process of cell division.
7. What is a centrosome, and how is it significant to the process of mitosis?
8. How would you identify a cell based on appearance undergoing metaphase
during mitosis?
9. How are prophase and telophase opposites?
10. Does the creation of a cell plate play a role in cytokinesis of plant or animal cells?
11. Explain the process of Somatic Cell Nuclear Transfer.
12. What stage of mitosis is the cell below experiencing? How do you know?
Homework
13. Provide two reasons for why cells would undergo mitosis.
14. What are the two major divisions of the cell cycle?
15. Identify the three ‘sub-phases’ of interphase, and explain the major goal of each
sub-phase.
16. What is the difference between a chromosome and a chromatid?
17. What is the difference between cytokinesis and mitosis?
18. Explain the relationship between a kinetochore and the spindle fibers during
mitosis.
19. Briefly describe what occurs during anaphase.
20. Why are vesicles important to the process of cytokinesis in plant cells?
21. In what type of cell would you find a cleavage furrow during cytokinesis?
22. It may be said that in plant cells, cytokinesis occurs from inside-out, while in
animal cells the process occurs from the outside-in. Explain why this statement
is true.
23. Compare anaphase to fishing. What similarities might exist between the two?
24. What is cloning?
25. Does an animal produced through SCNT resemble the organism that donated
the nucleus or the organism that donated the egg cell?
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Mitosis & Meiosis
26. What stage of mitosis is the cell below experiencing? How do you know?
Cell Cycle Control System
Classwork
27. Why do cells have a control system built into the cell cycle?
28. Explain the relationship between cancer and the cell cycle.
29. What is G0?
30. Explain what contact inhibition is and how it helps regulate cell division.
31. Is tumor metastasis usually related to benign or malignant tumors? Why does
this have a negative effect on the body?
32. Explain the relationship between chemotherapy and mitosis. How does
chemotherapy specifically affect mitosis?
33. Would a patient receiving chemotherapy or radiation for cancer treatment be
more likely to exhibit bodily symptoms such as hair loss and nausea? Explain
your answer.
34. Explain the value of stem cell therapy for treating different types of cancers.
35. Does an embryonic stem cell or an adult stem cell have a greater potential for
differentiation? Explain your answer.
Homework
36. How many checkpoints exist throughout the cell cycle?
37. Mature human nerve cells exist at which phase of the cell cycle?
38. Explain the role that contact inhibition plays in regulating or not regulating cancer
cells.
39. What is the difference between a benign and malignant tumor?
40. What differences exist between chemotherapy and radiation treatment?
41. A bone marrow transplant is most commonly used to treat which type of cancer?
42. Compare the checkpoints of a cell cycle to traffic lights. How are the two similar
in function?
43. What is the difference between a stem cell that is pluripotent and one that is
multipotent? Provide an example of a type of cell that would fall under each of
these categories.
Meiosis
Classwork
44. What is the scientific term for a reproductive cell that utilizes meiosis for
reproduction?
45. If n represents a haploid number of chromosomes, 2n would represent a
_______________ number of chromosomes.
46. Provide a possible suggestion for what purpose a doctor would utilize a
karyotype.
47. What is an allele? Provide two possible alleles for hair color in humans.
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Mitosis & Meiosis
48. How many cells are produced through meiosis? How many chromosomes do
each of these cells have in humans?
49. Explain how crossing over can increase the genetic diversity within a population
through meiosis.
50. What is independent assortment? How does independent assortment affect
genetic diversity?
51. What is nondisjunction?
52. Explain how you could use a karyotype to identify trisomy in an unborn child.
53. If Turner’s Syndrome is the result of nondisjunction causing monosomy of the
sex chromosomes, what is the combination of sex chromosomes in an individual
experiencing Turner’s Syndrome?
54. Predict the appearance of a karyotype of a zygote demonstrating polyploidy.
Homework
55. Do somatic cells contain a haploid or diploid number of chromosomes?
56. What are homologous chromosomes?
57. How would the karyotype of a female differ from the karyotype of a male?
58. Explain how the process of meiosis can reduce the number of chromosomes
present in a daughter cell.
59. Does crossing over increase genetic diversity in somatic cells? Why or why not?
60. With the exception of the number of chromosomes present, what other cell
division process does meiosis II resemble?
61. How can an error in meiosis potentially lead to birth defects?
62. What is aneuploidy? What are the two different possible results of a zygote
exhibiting aneuploidy?
63. Is nondisjunction resulting in a zygote lacking a second sex chromosome always
fatal? Explain your answer.
64. How does polyploidy affect plants differently than humans? Explain your answer.
65. How many chromosomes would be present in the karyotype of an individual who
has trisomy 21?
Illustrations courtesy of www.macroevolution.net
Free Response
1. Mitosis and Meiosis are two distinct types of eukaryotic cellular reproduction.
Compare and contrast them by responding to the prompts below:
a. When a cell undergoes mitosis, how many cells are produced and how
does their chromosome number compare to the parent cell?
b. When a cell undergoes meiosis, how many cells are produced and how
does their chromosome number compare to the parent cell?
c. List three reasons why a eukaryotic cell might undergo mitosis.
d. Why would a eukaryotic organism produce cells via meiosis?
2. Compare and contrast cancer cells and “normal” cells by responding to the
prompts below:
a. Describe the primary difference between cellular reproduction in cancer
cells and in non-cancerous cells.
b. What do tumors consist of and what are the specific differences between
malignant and benign tumors?
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Mitosis & Meiosis
3. Compare and contrast the two primary methods of cancer treatment by
responding to the prompts below.
a. Radiation therapy is non-systemic but chemotherapy is systemic. Explain
the difference between systemic and non-systemic.
b. Chemotherapy typically targets which structure found in the process of
mitosis? How would the destruction of this structure affect mitosis?
c. Radiation typically targets which structure found in cells? How would this
affect mitosis?
4. Below is an image that represents the chromosomes found within a human cell.
Use this image to respond to the prompts below.
a. Is this the karyotype of a human somatic cell or a human gamete?
Explain your response.
b. Does the karyotype above represent a male or a female? Explain your
response.
c. Does this karyotype demonstrate any chromosomal abnormalities? If so,
specify the type of abnormality; if not, why not?
5. The image below illustrates chromosomes during metaphase 1. The darker Xs
represent the chromosomes from the mother, while the lighter Xs represents the
chromosomes from the father. Use this illustration to respond to the prompts
below.
http://www.vce.bioninja.com.au/aos-3-heredity/cell-reproduction/meiosis.html
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Mitosis & Meiosis
a. What is the term for this variation in the way that chromosomes can line
up during metaphase 1 of meiosis?
b. How does this lead to increased genetic variation in offspring?
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Mitosis and Meiosis Answer Key
1. Mitosis has five stages, results in two identical diploid cells, occurs in somatic cellsMeiosis has 10 stages, results in four unique haploid cells, used to produce
gametes
2. Any body cell, such as skin, hair, nails, etc
3. No. Interphase prepares the cell for cell division.
4. The chromosomes are replicated.
5. Organelles are duplicated during G1, chromosomes are duplicated during the S
phase
6. Cytokinesis divides the cytoplasm, which contains the organelles and important
chemicals and energy, making sure that both new cells contain adequate organelles
and nutrients for functional survival.
7. A centrosome is a microtubule organizing center, and it is crucial to mitosis because
the microtubules provide a framework for the chromosomes to move during the
process.
8. The chromosomes would be lined up along the center of the cell
9. During prophase the nuclear envelope disappears, during telophase the envelope is
reestablished
10. Plant cells
11. This is a type of cloning- the steps are as follows: Remove nucleus from egg cell,
remove nucleus from somatic cell belonging to individual you want to clone, transfer
nucleus into empty egg cell, implant new egg cell into carrier organism, ensure egg
cell begins embryonic development and carries new cloned organism to term
12. Anaphase, the chromosomes are being pulled towards opposite poles of the cell
13. Repair damage, regenerate lost parts, grow in size, reproduce asexually
14. Interphase and mitotic phase
15. G1, S, G2- G1: grow, produce proteins, replicate organelles S: replicate DNA G2:
finish growing, final preparations for mitosis
16. Chromatids are chromosomes that have been copied in preparation for mitosis
17. Cytokinesis is the separation of the cytoplasm and the creation of new cell walls and
membranes, mitosis is the creation and separation of two nuclei
18. A kinetochore is a protein structure in the centromere connecting chromatids, the
spindle fibers that will pull the chromatids apart attach at the kinetochore
19. The chromatids are pulled apart to separate poles of the cell during anaphase
20. Vesicles merge together to create a new cell membrane during cytokinesis in plant
cells
21. Animal cell
22. In animal cells, the cleavage furrow pinches from the outside in to create two new
cells, whereas in plant cells vesicles and the cell plate form inside the cell and
eventually separate the cell into two new cells
23. The chromatids are the fish, with the spindle fibers being the fishing line and the
centrosome being the pole, reeling the chromatids to opposite ends of the cell
24. Cloning is creating an exact replica of a chosen organism
25. The organism that donated the nucleus, because the nucleus contains the genetic
material, the empty egg cell does not
26. Metaphase, the chromosomes are lined up in the middle of the cell
27. The control system is used to regulate cell growth and division, to ensure that cells
reproduce at a rate that is conducive to overall organismal health
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28. Cancer disables the ability of the cell to regulate the cell cycle. This causes
affected cells to grow and divide uncontrollably, creating the tumors that are
associated with the disease
29. G0 is a stage that non-dividing cells are perpetually stuck in, because they never
pass the G1 checkpoint and proceed with division
30. Contact inhibition is a process that regulates cell division by stopping the cell cycle
when a cell physically comes into contact with other cells. This prevents cells from
dividing too rapidly.
31. Metastasis is usually associated with malignant tumors. This allows cancer cells to
spread throughout the body much more rapidly.
32. Chemotherapy is used to slow cell division by disrupting the mitotic spindle used in
mitosis. By disrupting mitosis, chemotherapy prevents both cancer cells and normal
cells from dividing.
33. Chemotherapy. Since chemotherapy is more of a general medication, it affects
both healthy and affected cells, resulting in systemic side effects.
34. Stem cell therapy is specifically used for treating cancers of the blood. Stem cells
are particularly effective because they are undifferentiated cells that may develop
into whatever type of cell is needed by the body. This could potentially supply a
sick individual with a reserve of healthy cells for the affected body part(s).
35. Three
36. Embryonic- embryonic cells are pluripotent, which means they have the ability to
differentiate into pretty much any cell in the body, whereas adult stem cells are
multipotent, which means that their differentiating ability is limited
37. Nerve and muscle cells exist at G0, meaning they will not continuously grow and
divide, but instead will stay in their existing state.
38. Contact inhibition causes cells to stop dividing when they physically contact another
cell. Cancer cells do not exhibit contact inhibition, which is one of the reasons they
will continuously divide out of control.
39. A benign tumor is non-life threatening or otherwise damaging; malignant tumors can
metastasize and spread the cancer to other parts of the body, and can be lifethreatening
40. Chemotherapy consists of a combination of medicines administered which will
disrupt the reproduction process of cancerous and healthy cells in the body,
whereas radiation treatment is used on localized areas of the body.
41. Blood cancers
42. Just as a traffic light controls whether vehicles can proceed or need to stop, a
checkpoint controls whether the cell can divide, or if it must stop.
43. Pluripotent stem cells can differentiate into most other types of cell in the body,
multipotent stem cells are limited in their differentiation abilities. Embryonic stem
cells are pluripotent, adult stem cells, contained in organs that must regenerate lost
cells or continue to grow, are multipotent.
44. Gamete (sperm or egg)
45. Diploid
46. Doctors can use karyotypes to diagnose chromosomal disorders by analyzing the
number and shape of chromosomes
47. An allele is a alternative version of a gene. For example, you may have a brown
allele or black allele for the hair color gene
48. One round of meiosis produces 4 daughter cells. In humans, each cell has 23
chromosomes
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49. Crossing-over exchanges pieces of homologous chromosomes during each round
of meiosis, ensuring that each cell produced through meiosis has a unique set of
DNA
50. Independent Assortment is the fact that chromosomes align independently of each
other during metaphase 1 of meiosis. This increases genetic diversity because the
chromosomes will align differently through each round of meiosis, and with 23 pairs
of chromosomes, there are 8 million different potential combinations of
chromosomes
51. Nondisjunction is when chromosomes do not separate correctly during meiosis,
resulting in gametes with an incorrect number of chromosomes.
52. Trisomy would be exhibited by identifying three chromosomes at one of the 23
locations in a karyotype
53. An individual with Turner’s syndrome would have XO, meaning she would have one
X chromosome, and would lack a second sex chromosome. Monosomy indicates
only one chromosome, and YO would be fatal.
54. A zygote with polyploidy will have a full extra set of chromosomes
55. Diploid
56. Homologous chromosomes are the same size, shape and contain the same genes,
one is received from each parent
57. A male would have the sex chromosome combination of XY, Females have XX
58. Instead of replicating DNA after the first round of meiosis, the second round
continues without replication, ensuring that the number of chromosomes in the
daughter cells is half that of the parent cells
59. No. Crossing over only occurs in gametes
60. Meiosis II is pretty much identical to mitosis, without the same number of
chromosomes
61. If fertilization occurs between two cells that do not have the correct number of
chromosomes, or have experienced some form of nondisjunction, birth defects often
result from this process
62. Aneuploidy is when fertilization occurs involving a gamete that has experienced an
error in chromosome separation, monosomy and trisomy are both possible results
63. No, as long as one X chromosome is present, monosomy of sex chromosomes is
not fatal. If only a Y chromosome is present, it would be fatal
64. Polyploidy in plants sometimes results in larger, more productive plants, and is
sometimes necessary for the completion of a life cycle. In humans, it is fatal.
65. 47
1. Types of Cellular Reproduction
a. Mitosis results in two cells where there was one. The parent cell and the
daughter cell have the same number (diploid) of chromosomes.
b. Meiosis results immediately in four cells. All of the cells have half the
chromosome number (haploid) of the original cell.
c. Mitosis occurs when older cells must be replaced, when an organism is
growing, when a repair is being made within an organism, to reproduce
asexually (if this is possible for the organism), to regenerate a lost part. (any
three of these listed)
d. In order for offspring to have the correct number of chromosomes within its
cells (diploid, the same number as parent cells), during sexual reproduction,
the number of chromosomes in gametes (or egg and sperm) must be halved.
When gametes then combine, the correct number of chromosomes exist in
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Mitosis & Meiosis
2.
3.
4.
5.
the developing organism. Meiosis accomplishes this halving of the
chromosome number.
Cancer
a. Cancer occurs with uncontrolled cell division. The cell cycle control system
stops regulating the correct amount cell reproduction, so cell reproduction
(mitosis) continues unchecked. In non-cancerous cells the cell cycle control
system is in the “off” position during G1 (gap 1) and G2 (gap 2) and cell
reproduction (mitosis) cannot go forward unless a specific signal occurs that
allows mitosis to proceed.
b. Tumors are masses of cells that do not respond to contact inhibition and
continue dividing past any need for new cells. The term malignant is given to
cancers that are harmful and/or lethal by damaging surrounding tissues.
Benign tumors are masses of cells that do not severely damage surrounding
tissues and that are not life threatening.
Cancer Treatment
a. Non-systemic means that the treatment, radiation, most affects the cells in
the location where it is applied. Systemic treatments, such as chemotherapy,
affect the cells throughout the body – in addition to the cancerous cells.
b. Chemotherapy most typically disrupts the formation of spindles. Without
these structures the chromatids cannot travel from the center of the dividing
cell (during mitosis) to the poles during anaphase. Mitosis cannot
successfully occur.
c. Radiation damages the DNA inside of cells, which does not allow the cells to
continue dividing.
Karyotype
a. This is a karyotype of a somatic cell. There are 46 total chromosomes, the
number found in a diploid cell, which is a somatic cell.
b. This is the karyotype of a male. By definition, if cells contain a Y
chromosome, regardless of how many X chromosomes may be present, the
organism is male.
c. There are no chromosomal abnormalities. There are 23 pairs of
chromosomes in this karyotype, therefore, this is a normal male.
Meiosis
a. Chromosome can line up during metaphase 1, in any combination of
chromosomes from mother or father. This is called independent assortment.
b. Independent assortment allows a gamete to carry some chromosomes from
the mother and some chromosomes from the father. This random
assortment means that brothers and sisters receive differing amounts of
chromosomes from either parent – with them all still adding up to 46 total.
Therefore, siblings may appear (or produce proteins) extremely similarly to
completely differently depending upon this random independent assortment.
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