Download Cell Cycle Study Guide - KEY

Cell Cycle Study Guide - KEY
Define the following terms.
1. Binary fission –
asexual reproduction by bacteria (splitting in 2)
2. Cell Cycle –
life cycle of a cell (interphase, mitosis, cytokinesis)
3. Nuclear Envelope –
nuclear membrane
4. Centromere –
holds sister chromatids together in a chromosome
5. Kinetochore –
protein on the centromere that allows spindle fibers to attach to chromosomes
6. Centrosome (which contains centrioles in animals) –
contains centrioles which make/anchor spindle fibers
7. Cleavage furrow –
indention made in the cell membrane during cytokinesis
8. Cell plate –
Plants can’t have a cleavage furrow because of their cell wall. They instead make a new cell
wall between the 2 new cells. This developing cell wall is called a cell plate.
9. Somatic cell –
diploid “body” cell
10. Gametes –
haploid sex cells
11. Diploid –
2n – cell contains both members of homologous chromosome pairs. All somatic cells are this
type.
12. Haploid n – cell contains only 1 member of homologous chromosome pairs. All gametes are this type.
13. Sister chromatids –
identical copies on left and right side of a chromosome – made during interphase
14. Homologous chromosomes –
chromosomes that are the same size, shape, and carry the same genes. These are the “pairs”
of chromosomes that we all have (1 from mom and 1 from dad)
15. Autosomes –
homologous chromosome pairs 1-22. They are the same for boys and girls
16. Sex chromosomes –
23rd homologous chromosome pair. XX = girls and XY = guys
17. Karyotype –
picture of homologous chromosome pairs ordered from largest to smallest
18. Centrosome –
makes spindle fibers
19. Centriole –
Only in animal cells. Inside centrosomes. Function is to anchor spindle fibers.
20. Centromere –
Group of proteins that hold together sister chromatids
21. Kinetochore –
disc like protein on centromere where spindle fibers connect to chromosome
Questions
22. How are prokaryotic and eukaryotic DNA different (Hint: talk about the # and shape of the
chromosomes)?
Prokaryotes have a single, circular strand of DNA.
Eukaryotes have multiple linear chromosomes that occur in pairs
23. What is binary fission?
asexual reproduction by bacteria (splitting in 2)
24. Amoebas are classified as Protists which means they are eukaryotes (have nucleus and membrane
bound organelles) but they are unicellular. Like bacteria, they are unicellular and reproduce
asexually. Even so, they must reproduce by mitosis and not binary fission. Why? (Do not write
“because they are eukaryotes”. What is it about being eukaryotic that makes them us mitosis
instead of binary fission?)
They can’t do binary fission because they can’t just “split in 2” because of their nucleus and
multiple chromosomes. They must do mitosis which still results in 2 clone cells.
25. Draw a eukaryotic chromosome and label the following: DNA, gene, chromatid, centromere,
kinetochore.
The chromosome is 1 piece of DNA. There are multiple genes (segments of DNA) on each
chromosome that would be the same on the left and right side. The kinetochore would be a
protein located on the centromere.
26. How are chromatin and chromosomes different?
Chromatin is DNA that is loose because it is not wrapped around histone proteins (looks
like spaghetti). DNA is in this form in interphase where it can be used but not divided.
Chromosomes are the exact same genetic material, but it is wrapped tightly around histone
proteins. DNA is in this form during mitosis where it cannot be used but can be divided
easily.
27. Draw a diagram showing how much time a cell spends in each stage of the cell cycle (I phase =
Interphase, M phase = Mitosis, C phase = cytokinesis).
28. Describe what occurs in each of the 3 phases of interphase. (Gap/Growth 1, Synthesis, and
Gap/Growth 2). Note: Gap/Growth 0 (G0) is the name given to a cell if it IS NOT going to
divide. These cells stay in interphase forever.
G1: Growth of the cell after division
S: replication of DNA
G2: continued growth of the cell to prepare for cell division
29. We talked about 4 stages of mitosis. List those 4 stages in order and describe what occurs during
each of these stages.
Prophase
 Hint to remember: Pro- means before. This stage is everything that must happen BEFORE
the cell can divide
 3 major occurrences of prophase:
o Chromatin becomes more tightly coiled, forming chromosomes so it can be divided
evenly
o Centrosomes (with centrioles in animals) make spindle fibers made of microtubules
o The nucleus & cytoskeleton are broken down and used to make the spindle fibers.
The nucleolus also disappears.
Metaphase
 Motor proteins connected to the spindle fibers have lined up chromosomes in the equator of
cell. This is called the metaphase plate.
 The two kinetochores of the chromatids face opposite poles of the spindle.
 Hint to remember: Metaphase = middle
Anaphase
 Spindle fibers pull the centromeres of each chromosome apart, separating the sister
chromatids.
 Once separated each chromatid is now considered a full fledged daughter chromosome.
 Chromosomes are then pulled away from each other to the poles of the cell.
 Hint to remember: “AAA” = Anaphase, Apart, Away
Telophase
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Telophase is the end of mitosis; therefore, it is the exact opposite of prophase.
Cell elongation continues.
Daughter nuclei appear at the two poles.
Nuclear envelopes form around the chromosomes.
Chromosomes begin to uncoil, into chromatin.
Nucleolus reappear.
Mitotic spindle disappears.
Add: Hint to remember – Telophase – Two
30. What is cytokinesis, and how is it different between plants and animals?
Division of the cytoplasm. Plants = cell plate and animals = cleavage furrow
31. The following questions about mitosis have 2 possible answers given. Circle the correct answer.
1. What types of cells do mitosis?
somatic or gametes
2. Mitosis makes how many cells?
2 or 4
3. Mitosis makes what type of cells?
Diploid or Haploid
4. After mitosis, the daughter cells are related to the parent cells how?
5. Identical or Different
32. Mitosis has 3 purposes. List them.
Grow, repair, replace
33. Spindle fibers are a type of microtubules. What are microtubules?
Biggest part of the cytoskeleton.
Hollow tubes made of tubulin.
34. During what stage(s) of the cell cycle is DNA in chromatin form (Interphase or Mitosis)? Why?
Interphase so it can be used
35. During what stage(s) of the cell cycle is DNA in chromosome form (Interphase or Mitosis)?
Why?
Mitosis so it can be divided
36. During what phase of mitosis does the nuclear envelope disappear and when does it reappear?
Disappears in prophase so the DNA can be taken out of the nucleus and reappears in
telophase after the cell is done dividing
37. Which phase of mitosis is essentially the opposite of prophase in terms of nuclear changes? Why?
Telophase. Prophase begins cell division and telophase ends it.
38. Very important to know. During S phase of interphase you duplicate your DNA so you have
doubled the amount DNA. Even so, the number of chromosomes remains the same. Explain.
(Hint: use the terms centromere and sister chromatid)
You count the number of chromosomes by the number of centromeres. When you duplicate DNA,
you still have the same number of centromeres. You now just have 2 copies of the same DNA.
39. Very important to know. During anaphase of mitosis, you double the number of chromosomes
because you separate the sister chromatids into daughter chromosomes. How do you count the
number of chromosomes in a cell?
Count the number of centromeres. Once the centromere breaks, the sister chromatids are
considered 2 separate chromosomes.
Use the following diagram to answer questions 33-38
1
2
40. Write the name of each of the phases above.
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
3
4
41. During what stage do the spindle fibers eventually connect to the chromosomes?
At the end of prophase/start of metaphase
42. What stage shows the nuclear envelope being reformed?
telophase
43. Which stage shows the chromosome number doubling?
Anaphase (because the sister chromatids are separated there are now double the
centromeres)
44. Which stage shows chromatin condensing to chromosomes?
Prophase (preparing to divide)
45. Which stage shows centrosomes making spindle fibers?
Prophase (to prepare to divide)
46. Does a plant have centrioles?
No, has cell wall for spindle fibers to connect to.
47. What type of cells are centrioles found in (animal, plant, or prokaryotic), and what are they for?
animal cells; to anchor spindle fibers during cell division
48. What is cancer?
Uncontrolled cell division
49. What is metastasis?
Cancer spreading through the blood
50. Cancer occurs when your body doesn’t catch that there is a problem with a cell during any of the
3 checkpoints. What are the 3 checkpoints during the cell cycle, and what does each check for?
1. At the end of G1. Check to make sure there are no errors in the DNA before copying in S
phase. Called the point of no return because once a cell copies its DNA in S phase, it will
divide.
2. At the end of G2. Check to see if you have 2 sets of DNA and 2 sets of organelles before
doing mitosis.
3. At the end of Metaphase. Check to see if all of the replicated chromosomes are in the
middle of the cell and if they are all attached to spindle fibers.
51. What is the difference between Carcinomas, Sarcomas, & Lymphomas?
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Carcinomas – cancer originating in the external or internal coverings of the body.
(skin, intestine)
Sarcomas – cancer arising in tissues that support the body. (bone & muscle)
Leukemias & Lymphomas – cancer arising from blood forming tissues. (bone
marrow, spleen, & lymph nodes)
52. What is the difference between a Benign & Malignant tumor?
Benign means it is not moving through metastasis. Malignant means the cancer is spreading
to other parts of the body through blood.
53. What are cells that are not a sperm or egg called? What are chromosomes not involved in
determining sex of an organism called?
Somatic cells; autosomes
Cell Communication
54. What is the function of the ECM?
INTERcellular communication, Holding cells together in tissues
Protection for animal cells
55. What are the 4 types of cell junctions? Explain the function of each.
Gap = movement of things between cells
Tight = holding cells together so nothing leaks out (Ziploc bag)
Anchoring = Holding cells in a tissue together (door hinge)
Plasmodesmata are the gap junctions of plants.
56. Provide examples of where each type of junction might be found.
Gap = any cells that secretes products
Tight = stomach cells
Anchoring = skin cells
Plasmodesmata = any part of plant that secretes something
57. Which type of cell junction is plasmodesmata most like?
Gap junctions
58. Cells have 3 different ways of signaling amongst themselves. Define each of the following types of
cell signaling.
1. Direct –
Physical Contact between cells
2. Local –
Communicating with cells in a small area by releasing a signal into that area
3. Long Distance i. Hormones –
Making a signal in one part of the body, releasing it into the blood, and having it
used in another part of the body.
ii. Pheromones –
Releasing a signal into the environment to be picked up by another organism.
Used for mate attractant, trail marking, territory marking, etc.
59. What is a ligand?
Signal molecule
60. The signal transduction pathway has 3 parts. For each, tell what occurs during that stage and its
purpose.
1. Reception
i.
What occurs?
Receptor protein binds to a ligand. Receptor changes shape
ii.
Purpose?
To receive signal
2. Signal Transduction
iii.
What occurs?
Signal is passed through the cytoplasm in a series of steps.
iv.
Purpose?
Amplify signal
3. Response
v.
What occurs?
Cell performs an action
vi.
Purpose?
To perform whatever function the ligand signaled for