Download Mitosis Review Sheet KEY

Mitosis Review Sheet
KEY
1. List and describe what is occurring during the 2 general stages of the cell cycle.
Interphase – cells growth and DNA replication
Cell division – the nucleus and cytoplasm divide into two identical cells
2. List and describe what is occurring during each of the 3 stages of interphase.
i) G1 – phase – general cell growth
ii) S – phase - DNA replication
iii) G2 – phase - general cell growth and preparation for cell division.
3. What are the 2 sub stages of cell division?
mitosis and cytokinesis
4. Define mitosis.
Part of cell division, mitosis is the process of nuclear division.
5. What are the 4 true phases of mitosis.
i) prophase
ii) metaphase
iii) anaphase
iv) telophase
6. Explain cytokinesis?
Part of cell division, cytokinesis is the dividing of the cytoplasm and its organelles
7. If a plant cell has 24 DNA strands, how many DNA strands will be found in a given cell at the end of
each of the following: (for this question count 1 replicated chromosome comprised of 2 daughter
chromosomes as 2 DNA strands):
G1 24
S 48
G2 48
Prophase 48
Metaphase 48
Anaphase 48
Telophase 48
Cytokinesis 24
8. List 2 differences between plant and animal cell mitosis.
animal cells have cleavage furrowing and plant cells have only a cell plate
animal cells have centrioles and aster, plant cells do not
9. Explain the difference between chromatin and a chromosome.
Chromatin is extremely long, thin strands of DNA found in a nucleus during interphase.
A chromosome is an individual strand of replicated chromatin that has coiled and condensed into
a visible “X” like structure.
10. Explain the difference between a chromosome and 2 sister chromatids.
A chromosome is comprised of two sister chromatids, each of which are exact copies of one
another.
11. What is a centromere?
Both the point of attachment that holds sister chromatids together, as well as the point of
attachment for the spindle fibres.
12. What is the role of the spindle?
To attach to the centomeres of chromosomes, so as to position the chromosomes in the equator of
the cell, and to later pull the sister chromatids apart.
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13. Sketch an animal cell in interphase and describe what is happening to the chromosomes.
(label cell membrane, nuclear membrane, chromatin)
chromosomes thin and duplicated
14. Sketch an animal cell in prophase and describe what is happening to the nucleus and chromosomes.
(label chromosomes, sister chromatids, centromere, nuclear membrane disintegrating)
chromosomes thick and visible
nucleus dissolving
centrioles migrating to poles
15. Sketch an animal cell in metaphase and describe what is happening to the chromosomes.
(label spindle fibres, centrioles)
chromosomes align in middle
centrioles at poles with asters
spindle fibres formed
16. Sketch an animal cell in anaphase and describe what is happening to the chromosomes.
(label cleavage furrowing, daughter chromosomes)
chromosomes pulling apart
17. Sketch an animal cell in telophase and describe what is happening to the cell membrane, nucleus, and
chromosomes. (label nuclear membrane reforming)
chromosomes reach poles
nucleus reforming
cell membrane pinching off
18. What is a clone?
An exact genetic copy of an organism
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19. Comment on the history of cloning in plants (both nature and human made).
Plants clone themselves – strawberries send out runners (stems), humans can clone plants easily (slips of plants).
20. Explain early animal cloning experiments involving frogs and later mammal embryos.
Initial enucleation and nuclear transfer experiments were successfully conducted with frogs
The first mammals cloned had only their embryos cloned. Not adults. Scientists were cloning an unknown.
21. Explain how Dolly was cloned (include the concepts of both enucleation and nuclear transfer).
Egg from donor sheep was enucleated, then nucleus from sheep to be cloned was transferred into
enucleated egg. The egg was grown in test tube until large enough to be placed in uterus of mother.
22. Exactly how was Dolly proven to be a clone.
Genetically identical to her “clone mother”
23. Explain the 2 major potential applications of human cloning.
Cloning for reproductive purposes.
Cloning for cells and/or organ production.
24. Explain what a nature made human clones is.
Identical twin. Monozygotic (1 eggs and 1 sperm).
25. Discuss some ethical considerations regarding human cloning.
Answers vary.
26. What is a stem cell (two points)?
Cell that can divide a certain number of times.
Cells that can specialize into any of the 210 different cell types.
27. Explain the three potential applications of stem cells.
Drug testing.
Genetic experiments.
Cells and/or organ production.
28. How are embryonic stem cells obtained?
From the inner cell mass of human embryos.
29. How are fetal stem cells obtained?
From the cell mass of human fetal tissue
30. Explain somatic cell nuclear transfer.
Using cloning techniques. Using enucleation and nuclear transfer to create an inner cell mass containing stem
cells.
31. Discuss some ethical concerns regarding obtaining stem cells from any of these three methods.
Answers vary.
32. Discuss the pros and cons of using adult stem cells.
Answers vary.
33. Describe cancer.
Uncontrolled cell division.
34. Describe the 4 typical gene mutations that can often lead to cancer.
Oncogenes tell cells when to divide “ON SWITCH”
Tumor Suppressor Genes tell cells when not to divide “OFF SWITCH”
Suicide Genes control apoptosis and tell the cell to kill itself if something goes wrong
DNA Repair Genes instruct a cell to repair damaged DNA.
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Extension
View prepared slides of white fish blastula cells using the microscope viewers. Sketch what you see in each stage.
Interphase
(label cell membrane, nuclear membrane, chromatin)
Prophase
(label chromosomes, sister chromatids, centromere, nuclear membrane disintegrating)
Metaphase
(label spindle fibres, centrioles)
Anaphase
(label cleavage furrowing, daughter chromosomes)
Telophase
(label nuclear membrane reforming)
Microscope Work – if instructed to do so
1. View prepared slide of an onion root tip.
2. Try to find cells in each of the stages of mitosis. (prophase, metaphase, anaphase, telophase)
3. Do you find dividing cells in all regions of the root tip? (explain)
4. Describe the location of the dividing cells in the root tip.
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