4.6-4.7 Flashcards
(145 cards)
1
Q
- All cells derive from other cells.
A
2
Q
- The eukaryotic cell division cycle is regulated.
A
3
Q
- Interphase is all about preparation.
A
4
Q
- M-phase is all about division.
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5
Q
- CDKs become active by binding to specific cyclins.
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6
Q
- If a mutation prevents CDKs from binding to cyclins
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the most likely effect on the cell cycle would be arrest of the cell cycle
7
Q
- If a mutation causes a cell to produce insufficient cyclin in G1
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the G1/S checkpoint would not be passed
8
Q
- An environmental change that leads to the production of less than the expected amount of cyclin would tend to decrease the activity of the CDK in G1.
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9
Q
- This would lead to decreased phosphorylation of the target protein.
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10
Q
- This in turn would lead to more cells being stopped at the checkpoint.
A
11
Q
- The cells of an insect species has 4 chromosomes in the G0 phase.
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12
Q
- A chromosome is a piece of DNA.
A
13
Q
- Eukaryotic cells divide by mitosis.
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14
Q
- Cell division involves cell division signals
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DNA replication
15
Q
- Prokaryotes reproduce by binary fission.
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16
Q
- The eukaryotic cell cycle has four phases: G1
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S (DNA replication)
17
Q
- Short-lived cyclins and their more permanent CDKs regulate the passage of cells through cell cycle checkpoints.
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18
Q
- DNA is packaged with proteins
A
especially histones
19
Q
- Mitosis can be divided into prophase
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prometaphase
20
Q
- During mitosis
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sister chromatids separate
21
Q
- During mitosis
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chromosomes align in the middle of the cell during metaphase.
22
Q
- During mitosis
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sister chromatids move toward opposite poles during anaphase.
23
Q
- During mitosis
A
chromosomes become visible during prophase.
24
Q
- Asexual reproduction produces clones
A
new organisms that are genetically identical to the parent.
25
25. The sexual life cycle involves **meiosis** and fertilization.
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26. Sexual life cycles can be **haplontic**
diplontic
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27. **Meiosis** produces four genetically distinct haploid gametes from a diploid parent cell.
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28. Homologs pair during **synapsis** and exhibit crossing over during prophase I.
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29. Meiosis I differs from mitosis because **homologs** separate but sister chromatids remain together.
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30. **Nondisjunction** during mitosis or meiosis results in aneuploidy
or polyploidy if all chromosomes are involved.
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31. A cell may die by **necrosis**
or it may self-destruct by genetically programmed apoptosis.
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32. **Apoptosis** is regulated by external and internal signals.
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33. Necrosis occurs when cells and tissues are damaged by **mechanical means** or toxins
or are starved of oxygen or nutrients.
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34. Necrotic cells often **swell up** and burst
releasing their contents into the extracellular environment and possibly causing inflammation.
35
35. Apoptosis
or **programmed cell death**
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36. Programmed cell death removes cells that do not **benefit** the organism.
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37. Before birth
a human fetus has weblike hands
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38. The longer cells live
the more prone they are to **genetic damage** that could lead to cancer.
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39. The events of apoptosis are similar in many **organisms**.
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40. During apoptosis
the cell becomes detached from its neighbors and its **chromatin** is digested by enzymes that cut the DNA.
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41. The DNA is cut into fragments of about **180** base pairs during apoptosis.
42
42. The cell forms membranous lobes
or "**blebs**
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Here are 100 fill-in-the-blank questions based on the provided source material
in chronological order:
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1. Diploid bananas have **22** chromosomes.
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2. Triploid bananas have **33** chromosomes.
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3. Triploid bananas are **larger** and **seedless**.
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4. Diploid bananas are **smaller** and produce **inedible seeds**.
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5. Triploid seedless **watermelon** exhibits a similar phenomenon to bananas regarding ploidy.
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6. Perhaps the best known
and certainly the most important
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7. In wheat
hybridization occurred between **species**
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8. Haploid gametes from two species (A and B) mated and formed a **diploid zygote** (chromosomes AB).
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9. Nondisjunction of all chromosomes occurred during mitosis in the wheat lineage
resulting in **tetraploid** (AABB) cells.
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10. Tetraploid cells in wheat then gave rise to fertile flowers
producing **AB** gametes.
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11. Modern bread wheat is the result of **two** such hybridization events.
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12. The hybridization events that led to modern bread wheat occurred about **8
000–10
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13. Modern bread wheat is an **allohexaploid** (AABBCC).
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14. Wheat’s properties of grain formation and environmental adaptation come from **three** different ancestral species.
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15. Other allopolyploid crops include **cotton
oats
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16. Meiosis produces **four** daughter cells.
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17. In meiosis
the chromosome number is reduced from **diploid** to **haploid**.
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18. Because of the **independent assortment of chromosomes** and the **crossing over of homologous chromatids**
the four products of meiosis are genetically distinct.
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19. Meiotic and mitotic errors
such as **nondisjunction**
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20. Several important crop plants
such as wheat
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21. Crossing over and independent assortment result in **unique daughter nuclei**.
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22. Rarely
a person is born with an extra X chromosome (XXY). This aneuploidy might arise from **nondisjunction** during meiosis in either the egg or sperm formation.
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23. **Polyploidy** is the condition of having more than two sets of chromosomes.
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24. Polyploidy might arise due to **nondisjunction** during mitosis or meiosis.
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25. An essential role of cell division in complex eukaryotes is to **replace dead cells**.
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26. Cells die due to **necrosis** or **apoptosis**.
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27. Necrosis occurs when cells and tissues are damaged by **mechanical means or toxins**
or are **starved of oxygen or nutrients**.
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28. Necrotic cells often **swell up and burst**.
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29. When necrotic cells burst
they release their contents into the **extracellular environment**.
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30. The release of cellular contents by necrotic cells can possibly cause **inflammation**.
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31. **Apoptosis**
or programmed cell death
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32. Apoptosis occurs during **normal developmental processes** and in **adult tissues** as well.
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33. Programmed cell death removes cells that **do not benefit the organism**.
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34. Before birth
a human fetus has **weblike hands**.
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35. The unneeded tissue between the fingers of a fetus disappears as the cells undergo **apoptosis**.
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36. Apoptosis in fetal development occurs in response to **specific signals**.
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37. The longer cells live
the more prone they are to **genetic damage**.
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38. Genetic damage in long-lived cells could lead to **cancer**.
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39. This is especially true of **epithelial cells** on the surface of an organism.
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40. Epithelial cells may be exposed to **radiation or toxic substances**.
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41. Such epithelial cells normally die after only **days or weeks**.
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42. These dead epithelial cells are replaced by **new cells**.
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43. During apoptosis
the cell becomes **detached from its neighbors**.
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44. In apoptosis
the cell's **chromatin is digested by enzymes**.
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45. These enzymes cut the DNA between the **nucleosomes**.
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46. The DNA is cut into fragments of about **180 base pairs** during apoptosis.
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47. The cell forms membranous lobes
or **“blebs
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48. These blebs break up into **cell fragments**.
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49. Surrounding
living cells usually **ingest the remains of the dead cell by phagocytosis**.
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50. Neighboring cells digest the apoptotic cell contents in their **lysosomes**.
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51. The digested components of apoptotic cells are **recycled**.
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52. Apoptosis is also used by plant cells in an important defense mechanism called the **hypersensitive response**.
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53. Plants protect themselves from disease by undergoing **apoptosis** at the site of infection.
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54. The infection could be by a **fungus or bacterium**.
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55. Because of their rigid **cell walls**
plant cells do not form blebs the way animal cells do.
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56. Instead
plant cells digest their own cell contents in the **vacuole**.
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57. Plant cells then release the digested components into the **vascular system**.
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58. A variety of **signals**
either external or from inside the cell
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59. Such signals include **hormones
growth factors
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60. These signals activate **specific receptors**.
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61. Activated receptors in turn activate **signal transduction pathways leading to apoptosis**.
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62. Some apoptotic pathways target the **mitochondria**.
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63. These pathways might increase the **permeability of mitochondrial membranes**.
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64. An important class of enzymes called **caspases** are activated during apoptosis.
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65. Caspases are **proteases**.
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66. Proteases **hydrolyze target molecules** in a cascade of events.
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67. The cell dies as the caspases hydrolyze proteins of the **nuclear envelope
nucleosomes
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68. Cell death can occur either by **necrosis** or by **apoptosis**.
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69. Apoptosis is governed by **precise molecular controls**.
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70. Necrosis is initiated by events such as **mechanical damage
toxins
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71. Apoptosis is initiated by events such as **hormonal signals
DNA damage
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72. Apoptosis is necessary for **normal development** (e.g.
removing webbing between fingers) and removing **damaged or unneeded cells**.
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73. Apoptosis is regulated by **various signals** (internal and external) that activate **signal transduction pathways** leading to the activation of **caspases**.
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74. Mitosis **adds** cells to organisms.
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75. Apoptosis **removes** cells from organisms.
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76. Under normal circumstances
the processes of mitosis and apoptosis are **balanced**.
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77. Unregulated cell division can lead to **cancer**.
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78. Cancer involves an **inappropriate increase in cell numbers**.
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79. One in **three** Americans will have some form of cancer in his or her lifetime.
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80. Cancer ranks **second only to heart disease** as a killer in the United States.
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81. Cancer cells differ from the normal cells from which they originate in two ways: they **lose control over cell growth** and they **can migrate to other locations in the body**.
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82. Cancer cells do not respond to extracellular signals such as **growth factors**.
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83. Instead
cancer cells divide more or less **continuously**
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84. Benign tumors **resemble the tissue they came from**
grow **slowly**
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85. Malignant tumors do **not look like their parent tissue at all**.
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86. Malignant cells often have **irregular structures**
such as variable nucleus sizes and shapes.
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87. The spreading of cancer is called **metastasis**.
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88. Metastasis results in **organ failures** and makes cancer very hard to treat.
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89. **Positive regulators** such as growth factors stimulate the cell cycle.
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90. **Negative regulators** such as retinoblastoma protein (RB) inhibit the cell cycle.
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91. Oncogene proteins are **positive regulators** in cancer cells.
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92. Oncogene proteins are derived from normal positive regulators that have become **mutated to be overly active** or that are **present in excess**.
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93. Tumor suppressors are **negative regulators** in both cancer and normal cells
but in cancer cells they are **inactive**.
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94. An example of a tumor suppressor is the **RB protein**.
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95. Another important tumor suppressor is **p53**
a transcription factor involved in cell cycle checkpoint pathways and apoptosis.
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96. More than **50%** of human tumors have mutations in the gene that encodes p53.
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97. In normal nongrowing tissues
the rate of cell division **equals** the rate of apoptosis.
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98. Cancer cells are defective in their regulation of the **cell cycle**
resulting in increased rates of cell division.
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99. Cancer cells can lose the ability to respond to **positive regulators of apoptosis**.
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100. Both increased cell division and lowered rates of apoptosis lead to an **increased growth rate of the cancer cell population**.
