4.2 Flashcards
(203 cards)
1
Q
There are four main events in all organisms related to cell derivation. four
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2
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- The first main event is cell division signals. cell division signals
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3
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- The second main event is DNA replication. DNA replication
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4
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- The third main event is DNA segregation. DNA segregation
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5
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- The fourth main event is cytokinesis. cytokinesis
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6
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- Signals to divide in prokaryotes are usually external factors. external factors
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7
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- Nutrient concentration is an example of an external factor that signals prokaryotic cell division. Nutrient concentration
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8
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- Environmental conditions are an example of external factors that signal prokaryotic cell division. Environmental conditions
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9
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- Cell division in prokaryotes (binary fission) results in reproduction of the entire single-celled organism. binary fission
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10
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- Most prokaryotes have one chromosome. one
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11
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- A prokaryotic chromosome is often circular
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but folded. circular
12
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- The ori region on a prokaryotic chromosome is where replication starts (origin). ori
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13
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- The ter region on a prokaryotic chromosome is where replication ends (terminus). ter
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14
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- After replication in prokaryotes
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ori regions move to opposite ends of the cell. ori regions
15
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- The movement of ori regions segregates the daughter chromosomes in prokaryotes. daughter chromosomes
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16
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- In prokaryotic cytokinesis
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the cell membrane pinches in. cell membrane
17
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- Protein fibers form a ring during prokaryotic cytokinesis. Protein fibers
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18
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- New cell wall materials are synthesized during prokaryotic cytokinesis. cell wall
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19
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- Prokaryotic cell division results in the separation of the two cells. separation
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20
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- Cell division signals in eukaryotes are related to the needs of the entire organism. entire organism
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21
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- Eukaryotic DNA replication is more complex than in prokaryotes. complex
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22
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- Eukaryotes have more than one chromosome. more than one
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23
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- Replication in eukaryotes starts at many origins on the chromosome. many origins
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24
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- Replication in eukaryotes is limited to one part of the cell cycle. one part of the cell cycle
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32. **Mitosis** separates the newly replicated chromosomes into two new nuclei in eukaryotes. **Mitosis**
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33. One **copy of each chromosome** ends up in each daughter cell after eukaryotic DNA segregation. **copy of each chromosome**
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34. Eukaryotic cytokinesis proceeds **differently** in animal and plant cells. **differently**
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35. Plants have **cell walls**
which affects their cytokinesis. **cell walls**
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36. A mutation acquired by a bacterium will very likely be inherited by **both** daughter cells. **both**
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37. Binary fission can be best described as DNA replication
DNA division
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38. In a dividing bacterial cell
A indicates **ori**. **ori**
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39. In a dividing bacterial cell
the cells labeled 1 and 2 are **genetically similar**. **genetically similar**
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40. In bacterial cell division
the function of the ori site is that **It is the origin of DNA replication**. **It is the origin of DNA replication**
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41. DNA replication is a critical step in cell division because **It ensures that each daughter cell receives an identical copy of the genome**. **It ensures that each daughter cell receives an identical copy of the genome**
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42. If a bacterial cell is placed in an environment with limited nutrients
it would likely **halt DNA replication until conditions improve**. **halt DNA replication until conditions improve**
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43. If a scientist observes two distinct ori regions at opposite ends of a dividing bacterial cell
she can conclude that **DNA replication has completed
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44. A mutation that disrupts the function of the ori site would affect **DNA replication and segregation** in binary fission. **DNA replication and segregation**
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45. A disruption of the ori site would likely impact **cytokinesis and overall cell division**. **cytokinesis and overall cell division**
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46. Chromosomes become highly **condensed** before they segregate. **condensed**
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47. Condensation makes chromosomes easier to move into the two new **nuclei**. **nuclei**
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48. The **spindle**
a special cytoskeletal structure composed of microtubules
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49. Cytokinesis proceeds differently in plant cells (which have a **cell wall**) than in animal cells. **cell wall**
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50. The cells resulting from mitosis are **identical** to the parent cell in the amount and kind of DNA they contain. **identical**
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51. **Meiosis** is another mechanism for nuclear division involved in gamete formation. **Meiosis**
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52. Four events are required for cell division: cell division signals
replication of the genetic material (DNA)
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53. Prokaryotes often have just **one** chromosome. **one**
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54. Eukaryotes usually have **multiple** chromosomes. **multiple**
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55. The process of cell division is more **intricate** in eukaryotes. **intricate**
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56. Commonly
**nutrient concentration** controls whether a prokaryotic cell will begin binary fission. **nutrient concentration**
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57. DNA must be **replicated** and **segregated** before the cell can divide. **replicated**
**segregated**
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58. DNA replication and cell division are more complex in eukaryotes than in prokaryotes because eukaryotes have **multiple chromosomes** and more intricate regulatory mechanisms. **multiple chromosomes**
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59. The **eukaryotic cell division cycle** includes the phases through which a single cell passes to produce daughter cells. **eukaryotic cell division cycle**
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60. The eukaryotic cell cycle can be divided into four phases: **G1**
**S**
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61. The **M phase** includes mitosis and cytokinesis. **M phase**
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62. The **G1**
**S**
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63. DNA replication occurs during the **S phase** of interphase. **S phase**
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64. During interphase
the cell **nucleus** is visible. **nucleus**
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65. Typical cell functions occur during **interphase**. **interphase**
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66. The duration of the cell cycle **varies considerably** in different cell types. **varies considerably**
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67. Cells in an early embryo may have a cell cycle as short as **30 minutes**. **30 minutes**
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68. Rapidly dividing cells in an adult human typically complete the cell cycle in about **24 hours**. **24 hours**
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69. In general
cells spend most of their time in **interphase**. **interphase**
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70. During **G1 phase**
each chromosome is a single
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71. Variations in the duration of **G1** account for most of the variability in the length of the cell cycle in different cell types. **G1**
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72. G1 ends at the **G1-to-S transition**. **G1-to-S transition**
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73. At the G1-to-S transition
the commitment is made to DNA replication and subsequent **cell division**. **cell division**
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74. During **S phase**
each chromosome is duplicated. **S phase**
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75. After duplication in S phase
each chromosome consists of two **sister chromatids**. **sister chromatids**
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76. Sister chromatids remain joined together until **mitosis**. **mitosis**
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77. During **G2 phase**
the cell makes preparations for mitosis. **G2 phase**
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78. Cells that do not divide usually arrest during G1 and enter **G0**. **G0**
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79. DNA is replicated during **S** phase. **S**
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80. Cell division—cytokinesis—occurs at the end of **M** phase. **M**
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81. The **restriction point (R)** is a checkpoint for progression through the cell cycle. **restriction point (R)**
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82. Specific **internal signals** trigger events in the cell cycle. **internal signals**
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83. Cell fusion experiments revealed the existence of internal signals that control the **transitions between stages** of the cell cycle. **transitions between stages**
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84. An experiment involving the fusion of HeLa cells showed that a cell in S phase produces a substance that activates **DNA replication**. **DNA replication**
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85. Nuclei of cells in **G1** do not undergo DNA replication. **G1**
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86. Nuclei in **S phase** do undergo DNA replication. **S phase**
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87. Rao and Johnson's hypothesis was that a cell in **S phase** contains an activator of DNA replication. **S phase**
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88. In the cell fusion experiment
both nuclei in the fused G1/S cell enter **S phase**. **S phase**
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89. **Sendai virus** was used as a tool to fuse cells experimentally. **Sendai virus**
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90. **HeLa cells** divide continuously. **HeLa cells**
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91. Before fusion
the cells in S phase were exposed to a **radioactively labeled component of DNA (thymidine)**. **radioactively labeled component of DNA (thymidine)**
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92. The radioactivity labeled the **nuclei** of the S phase cells. **nuclei**
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93. Progress through the cell cycle depends on the activities of **cyclin-dependent kinases**
or CDKs. **cyclin-dependent kinases**
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94. A protein kinase catalyzes the transfer of a **phosphate group** from ATP to a target protein. **phosphate group**
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95. The phosphate transfer is called **phosphorylation**. **phosphorylation**
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96. A particular CDK controls the **G1-to-S transition**. **G1-to-S transition**
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97. The G1-to-S transition is a control point called the **restriction point (R)**. **restriction point (R)**
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98. CDKs are not enzymatically active as protein kinases unless they are bound to another class of protein called **cyclins**. **cyclins**
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99. The binding of a cyclin activates the CDK by altering its **shape** and exposing its active site to substrates. **shape**
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100. The cyclin–CDK that controls passage from G1 to S phase is **not the only** such complex involved in regulating the eukaryotic cell cycle. **not the only**
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How many main events are there in all organisms related to cell derivation Four. What is the first main event in cell derivation Cell division signals
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What is the second main event in cell derivation? DNA replication
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What is the third main event in cell derivation? DNA segregation
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What is the fourth main event in cell derivation? Cytokinesis
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What usually signals cell division in prokaryotes? External factors
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Give an example of an external factor that signals prokaryotic cell division. Nutrient concentration
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Give another example of an external factor that signals prokaryotic cell division. Environmental conditions
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What is the name for cell division in prokaryotes? Binary fission. What does binary fission in prokaryotes result in? Reproduction of the entire single-celled organism
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How many chromosomes do most prokaryotes have? One
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Describe the typical structure of a prokaryotic chromosome. Often circular
but folded
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What does "ori" stand for in the context of prokaryotic chromosomes? Origin (where replication starts)
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What does "ter" stand for in the context of prokaryotic chromosomes? Terminus (where replication ends)
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What happens to the ori regions after DNA replication in prokaryotes? They move to opposite ends of the cell
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What does the movement of ori regions lead to in prokaryotes? Segregation of the daughter chromosomes
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What happens to the cell membrane during prokaryotic cytokinesis? It pinches in
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What forms a ring during prokaryotic cytokinesis? Protein fibers
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What materials are synthesized during prokaryotic cytokinesis? New cell wall materials
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What is the end result of prokaryotic cell division? Separation of the two cells
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What are eukaryotic cell division signals related to? The needs of the entire organism
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How does eukaryotic DNA replication compare to prokaryotic replication in complexity? It is more complex
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Question: How many chromosomes do eukaryotes have? More than one
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Question: Where does replication start on eukaryotic chromosomes? At many origins
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Question: When does replication occur in the eukaryotic cell cycle? Limited to one part of the cell cycle
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Question: What process separates newly replicated chromosomes into two new nuclei in eukaryotes? Answer: Mitosis
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Question: What is the outcome of eukaryotic DNA segregation in terms of chromosome copies in daughter cells? One copy of each chromosome ends up in each daughter cell
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How does eukaryotic cytokinesis differ between animal and plant cells? It proceeds differently
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What structural feature do plant cells have that affects cytokinesis? Cell walls
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Question: True or false: A mutation acquired by a bacterium will very likely be inherited by both daughter cells. True
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Question: Which of the following best describes binary fission: A. DNA replication
Cell division
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In a dividing bacterial cell
what does 'ori' indicate? The origin of DNA replication
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In a dividing bacterial cell
are the daughter cells genetically similar or different?Genetically similar
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Question: In bacterial cell division
what is the function of the ori site? It is the origin of DNA replication
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Question: Why is DNA replication a critical step in cell division? It ensures that each daughter cell receives an identical copy of the genome
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How might limited nutrients affect a bacterial cell's division process? It would likely halt DNA replication until conditions improve
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Question: If a scientist observes two distinct ori regions at opposite ends of a dividing bacterial cell
what can she conclude? DNA replication has completed
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Question: What two processes in binary fission would be affected by a mutation disrupting the ori site? Answer: DNA replication and segregation
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What are the likely impacts of an ori site mutation on cytokinesis and overall cell division? Likely impact on cytokinesis and overall cell division (The sources don't provide specific details on how it would impact cytokinesis without proper DNA replication and segregation
but it indicates there would be an impact).
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What happens to chromosomes before they segregate during cell division?Answer: They become highly condensed
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What is the cytoskeletal structure involved in moving chromosomes during segregation?The spindle
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Question: What are the cells resulting from mitosis in terms of their DNA content compared to the parent cell? Identical
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Question: What is another mechanism for nuclear division involved in gamete formation? Meiosis
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Question: How many key events are required for cell division? Answer: Four
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Question: Name the four key events required for cell division. Answer: Cell division signals
replication of the genetic material (DNA)
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What commonly controls whether a prokaryotic cell will begin binary fission? Nutrient concentration
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Why must DNA be replicated and segregated before the cell can divide? To ensure that each of the two new daughter cells receives a complete and identical copy of the genetic material
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Question: Why are DNA replication and cell division more complex in eukaryotes than in prokaryotes? Answer: Eukaryotes usually have multiple chromosomes
and the process of cell division is more intricate
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Question: What is the series of phases a eukaryotic cell passes through to produce daughter cells called? Answer: The cell cycle
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Question: Name the four phases of the eukaryotic cell cycle. G1
S
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Question: Which phase of the cell cycle includes mitosis and cytokinesis?M phase
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Question: What do the G1
S
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Question: During which phase of interphase does DNA replication occur? S phase
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Question: What is visible in the cell during interphase? The cell nucleus
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Question: Does the duration of the cell cycle vary? If so
among what? Yes
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Question: In general
do cells spend more or less time in interphase compared to M phase? More time
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What is the state of each chromosome during the G1 phase? A single
unreplicated DNA molecule with associated proteins
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Question: What accounts for most of the variability in the length of the cell cycle in different cell types? Variations in the duration of G1
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Question: What marks the end of the G1 phase? The G1-to-S transition
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What occurs during the S phase? DNA replication
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What are the products of DNA replication called? Sister chromatids
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When do sister chromatids segregate into daughter cells? During mitosis
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What occurs during the G2 phase? The cell makes preparations for mitosis
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What happens to cells that do not divide? They usually arrest during G1 and enter G0
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What is the inactive resting phase of the cell cycle called that some cells enter from G1? G0
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Can cells in G0 re-enter the cell cycle? If so
under what conditions? Yes
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Give an example of human cells that typically stay in G0. Cells of the heart (cardiac muscle) and brain (neurons)
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What did cell fusion experiments reveal about the cell cycle? The existence of internal signals that control the transitions between stages
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What did the fusion of HeLa cells in S phase with cells in G1 phase show? That a cell in S phase produces a substance that activates DNA replication
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What phase are the nuclei of cells in that do not undergo DNA replication? G1
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What phase are the nuclei of cells in that do undergo DNA replication? S phase
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What hypothesis did Rao and Johnson test in their cell fusion experiments? Answer: That a cell in S phase contains an activator of DNA replication
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What virus was used in the laboratory to fuse cells experimentally? Answer: Sendai virus
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What type of cells did Rao and Johnson use in their experiment? HeLa cells
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What was used to label the DNA of S phase cells before fusion? A radioactively labeled component of DNA (thymidine)
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What is the role of cyclin-dependent kinases (CDKs) in the cell cycle? They control progress through the cell cycle
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What type of enzyme is a protein kinase? An enzyme that catalyzes the transfer of a phosphate group from ATP to a target protein
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What is the transfer of a phosphate group from ATP to a target protein called?Phosphorylation
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Which transition in the cell cycle is controlled by a particular CDK? The G1-to-S transition
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What is the control point in the cell cycle called the G1-to-S transition? The restriction point (R)
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Are CDKs always enzymatically active? No
not unless they are bound to cyclins
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What are the activator proteins that bind to CDKs called? Cyclins
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How does cyclin binding activate a CDK? By altering its shape and exposing its active site to substrates (allosteric regulation)
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Are there different cyclin–CDK complexes in the eukaryotic cell cycle? Yes
that act at different stages
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Question: What does the G1/S cyclin–CDK catalyze the phosphorylation of?
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Answer: A protein called retinoblastoma protein (RB)
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What is the role of the RB protein in many cells at the restriction point (R)?Answer: It acts as an inhibitor of the cell cycle
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What happens to the RB protein when it is phosphorylated by the G1/S cyclin–CDK Answer: It becomes inactivated
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Question: What does the inactivation of RB protein allow to happen? Answer: The cell cycle can proceed through the restriction point
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Question: How is the activity of CDKs primarily regulated? By regulating the presence or absence of cyclins
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Question: When are cyclins typically present in the cell cycle? Cyclically: they are made only at certain times What are cell cycle checkpoints?
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Signaling pathways that regulate the cell cycle’s progress
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Question: How many checkpoints are there during interphase? Three
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How many checkpoints are there during mitosis? One
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Give an example of what might cause the cell cycle to pause at a checkpoint. If a cell’s DNA is substantially damaged or a chromosome is unattached to the spindle
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Question: What happens if DNA is damaged by radiation during G1 at the G1-to-S checkpoint
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Answer: A signaling pathway results in the production of a protein called p21
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Question: What does the p21 protein do? It binds to the G1/S CDK
preventing cyclin binding and keeping the CDK inactive
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What happens when the DNA damage is repaired? p21 breaks down
allowing cyclin–CDKs to function
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What happens if DNA damage is severe and cannot be repaired? The cell will undergo programmed cell death (apoptosis)
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What can stimulate cells to divide? Growth factors
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Are all cells in an organism constantly going through the cell cycle? No. Some enter G0 or divide infrequently
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What are growth factors? External chemical signals that can stimulate cells to divide
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Give an example of a situation where growth factors are involved in cell division.Platelets at a wound releasing platelet-derived growth factor to stimulate skin cells to divide and heal or interleukins and erythropoietin stimulating blood cell precursor division
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How do growth factors exert their effect on the cell cycle? They bind to specific receptors and activate signal transduction pathways that end with cyclin synthesis
thereby activating CDKs and the cell cycle
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What are CDKs controlled by in the eukaryotic cell cycle? The binding of cyclins
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Besides internal signals
what else controls the eukaryotic cell cycle? External signals such as growth factors
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What happens to the G1/S cyclin concentration during the cell cycle? Synthesis begins during G1
it binds to CDK making it active
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Question: What is a checkpoint trigger in the G1 phase? DNA damage
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Question: What is a checkpoint trigger in the S phase? Incomplete replication or DNA damage
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Question: What is a checkpoint trigger in the G2 phase? DNA damage
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What is a checkpoint trigger in the M phase? Chromosome unattached to spindle
