cell cycle Flashcards

1
Q

What happens during prophase in mitosis?

A

Chromosomes condense and become visible, the nuclear envelope breaks down, and spindle fibers form.

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2
Q

What is the role of spindle fibers during prometaphase in mitosis?

A

Spindle fibers attach to the kinetochores on the centromeres of chromosomes.

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3
Q

What happens during metaphase in mitosis?

A

Chromosomes align at the metaphase plate and spindle fibers attach to both sister chromatids of each chromosome.

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4
Q

What is the result of anaphase in mitosis?

A

Sister chromatids separate and are pulled towards opposite poles of the cell by spindle fibers.

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5
Q

What happens during telophase in mitosis?

A

Chromosomes reach opposite poles and begin to decondense, and nuclear envelopes start to reform.

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6
Q

What is cytokinesis in mitosis?

A

It is the division of the cytoplasm, usually beginning during telophase.

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7
Q

What is interphase in the cell cycle?

A

It is the period between mitotic divisions, where DNA replication occurs during the S phase.

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8
Q

What happens during the G1 phase of interphase?

A

The cell grows and carries out normal metabolic activities.

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9
Q

What happens during the S phase of interphase?

A

DNA replication occurs.

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10
Q

What happens during the G2 phase of interphase?

A

The cell prepares for mitosis by synthesizing proteins and organelles.

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11
Q

What is a checkpoint in the cell cycle?

A

A checkpoint is a control mechanism that ensures that a cell has completed necessary processes before progressing to the next stage of the cell cycle.

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12
Q

What is the purpose of the G1 checkpoint?

A

The G1 checkpoint ensures that the cell has enough resources and energy to begin DNA replication in the S phase.

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13
Q

What is the purpose of the G2 checkpoint?

A

The G2 checkpoint ensures that DNA replication was successful and that the cell is ready to enter mitosis.

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14
Q

What is the purpose of the spindle checkpoint?

A

The spindle checkpoint ensures that all chromosomes are properly attached to spindle fibers before the cell enters anaphase.

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15
Q

What happens if a cell fails the G1 checkpoint?

A

The cell enters a non-dividing state called G0, or undergoes apoptosis (programmed cell death).

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16
Q

What happens if a cell fails the G2 checkpoint?

A

The cell is prevented from entering mitosis, and DNA repair mechanisms are activated to fix any damage.

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17
Q

What happens if a cell fails the spindle checkpoint?

A

The cell is prevented from progressing to anaphase until all chromosomes are properly attached to spindle fibers.

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18
Q

How do checkpoint controls work?

A

Checkpoint controls involve specific proteins that detect DNA damage or incomplete processes, which then halt the cell cycle until the issues are resolved.

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19
Q

What is the significance of checkpoint controls in preventing cancer?

A

Checkpoint controls prevent damaged or mutated cells from proliferating, which can lead to the development of cancer.

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20
Q

What are some factors that can disrupt checkpoint controls?

A

Environmental toxins, radiation, and mutations in checkpoint control genes can all disrupt the normal functioning of checkpoints and increase the risk of cancer.

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21
Q

What are the gap phases in the cell cycle?

A

The gap phases are G1 and G2, which occur between DNA synthesis (S phase) and cell division (mitosis).

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22
Q

What happens during the G1 phase?

A

During G1, the cell grows and carries out normal metabolic activities, and checkpoint controls ensure that the cell has enough resources and energy to begin DNA replication in the S phase.

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23
Q

What is the duration of G1 phase?

A

The duration of G1 phase can vary depending on cell type, ranging from a few hours to several days.

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24
Q

What are some factors that can influence the duration of G1 phase?

A

Factors that can influence the duration of G1 phase include cell size, growth factors, and extracellular matrix signals.

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25
Q

What happens during the G2 phase?

A

During G2, the cell prepares for mitosis by synthesizing proteins and organelles, and checkpoint controls ensure that DNA replication was successful and that the cell is ready to enter mitosis.

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26
Q

What is the duration of G2 phase?

A

The duration of G2 phase is typically shorter than G1 phase, ranging from a few hours to a few days.

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27
Q

What are some factors that can influence the duration of G2 phase?

A

Factors that can influence the duration of G2 phase include the rate of DNA replication, the size of the cell, and the amount of damage in the DNA.

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28
Q

How is the transition from G2 to mitosis regulated?

A

The transition from G2 to mitosis is regulated by checkpoint controls that ensure that all chromosomes are properly attached to spindle fibers before the cell enters anaphase.

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29
Q

What happens if a cell fails the G1 checkpoint?

A

The cell enters a non-dividing state called G0, or undergoes apoptosis (programmed cell death).

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30
Q

What happens if a cell fails the G2 checkpoint?

A

The cell is prevented from entering mitosis, and DNA repair mechanisms are activated to fix any damage.

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31
Q

What is S phase?

A

S phase is the stage in the cell cycle where DNA replication occurs.

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32
Q

When does S phase occur in the cell cycle?

A

S phase occurs between the gap phases G1 and G2 and precedes mitosis.

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33
Q

What happens during S phase?

A

During S phase, DNA helicase unwinds and separates the two strands of DNA, and DNA polymerase synthesizes new complementary strands.

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34
Q

How is DNA replication initiated in S phase?

A

DNA replication is initiated at multiple sites on the chromosome called origins of replication.

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35
Q

What is the direction of DNA synthesis during S phase?

A

DNA synthesis occurs in a 5’ to 3’ direction, adding nucleotides to the 3’ end of the new strand.

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36
Q

How are the newly synthesized DNA strands separated during S phase?

A

The two newly synthesized DNA strands are separated by topoisomerases, which relieve tension in the double helix.

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37
Q

What is the outcome of DNA replication during S phase?

A

The outcome of DNA replication is two identical copies of the chromosome, called sister chromatids, which are separated during mitosis.

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38
Q

How is the accuracy of DNA replication ensured during S phase?

A

The accuracy of DNA replication is ensured by checkpoint controls, which detect and repair errors in DNA replication.

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39
Q

What are some factors that can disrupt DNA replication during S phase?

A

Environmental toxins, radiation, and mutations in genes involved in DNA replication can all disrupt the normal functioning of S phase and increase the risk of cancer.

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40
Q

What is the duration of S phase?

A

The duration of S phase varies depending on the cell type, but typically lasts for several hours to complete the replication of all chromosomes.

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41
Q

What are the key players in regulating the cell cycle?

A

The key players in regulating the cell cycle include cyclins, cyclin-dependent kinases (CDKs), tumor suppressor genes, and proto-oncogenes.

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42
Q

What are cyclins?

A

Cyclins are proteins that are produced and degraded in a cell cycle-dependent manner, and they regulate the activity of CDKs.

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43
Q

What are CDKs? cyclin-dependent kinases (CDKs)

A

CDKs are enzymes that phosphorylate target proteins to drive cell cycle progression.

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44
Q

How do cyclins and CDKs interact to regulate the cell cycle?

A

Cyclins bind to and activate CDKs, allowing them to phosphorylate target proteins and drive cell cycle progression.

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45
Q

What is the role of tumor suppressor genes in the cell cycle?

A

Tumor suppressor genes help prevent uncontrolled cell division by inhibiting the activity of CDKs or promoting cell cycle arrest.

46
Q

What is the role of the p53 tumor suppressor gene in the cell cycle?

A

The p53 tumor suppressor gene helps prevent uncontrolled cell division by promoting cell cycle arrest or apoptosis in response to DNA damage.

47
Q

What is the role of proto-oncogenes in the cell cycle?

A

Proto-oncogenes promote cell cycle progression by activating CDKs or stimulating the production of cyclins.

48
Q

What happens if proto-oncogenes become mutated and become oncogenes?

A

If proto-oncogenes become mutated and become oncogenes, they can promote uncontrolled cell division and contribute to the development of cancer.

49
Q

What is the role of checkpoint controls in the cell cycle?

A

Checkpoint controls ensure that a cell has completed necessary processes before progressing to the next stage of the cell cycle, helping prevent DNA damage and chromosomal abnormalities.

50
Q

How are checkpoint controls activated in the cell cycle?

A

Checkpoint controls are activated by DNA damage or incomplete processes, which halt the cell cycle until the issues are resolved.

51
Q

What is the role of the retinoblastoma (Rb) protein in the cell cycle?

A

The Rb protein helps regulate the G1 checkpoint by inhibiting CDK activity and promoting cell cycle arrest.

52
Q

How is the Rb protein regulated in the cell cycle?

A

The Rb protein is regulated by cyclin-CDK complexes, which phosphorylate and inactivate it, allowing cell cycle progression.

53
Q

What is the role of the anaphase-promoting complex (APC) in the cell cycle?

A

The APC helps regulate the transition from metaphase to anaphase by degrading cyclins and other regulatory proteins.

54
Q

How is the activity of APC regulated in the cell cycle?

A

The activity of APC is regulated by the spindle checkpoint, which ensures that all chromosomes are properly attached to spindle fibers before the cell enters anaphase.

55
Q

What are some factors that can disrupt the normal regulation of the cell cycle?

A

Environmental toxins, radiation, and mutations in genes involved in cell cycle regulation can all disrupt the normal functioning of the cell cycle and increase the risk of cancer.

56
Q

What are the signaling pathways involved in cell cycle progression?

A

The signaling pathways involved in cell cycle progression include growth factor signaling, extracellular matrix signaling, and the Ras-Raf-MEK-ERK pathway.

57
Q

How does growth factor signaling promote cell cycle progression?

A

Growth factors bind to cell surface receptors, activating intracellular signaling pathways that stimulate the production of cyclins and activate CDKs.

58
Q

What is the role of extracellular matrix signaling in cell cycle progression?

A

Extracellular matrix signaling regulates cell adhesion, migration, and survival, which can influence cell cycle progression.

59
Q

How does the Ras-Raf-MEK-ERK pathway promote cell cycle progression?

A

The Ras-Raf-MEK-ERK pathway promotes cell cycle progression by stimulating the production of cyclins and activating CDKs.

60
Q

What is the role of cyclin D in cell cycle progression?

A

Cyclin D binds to and activates CDK4 and CDK6, promoting the phosphorylation and inactivation of the Rb protein.

61
Q

What is the Rb protein and how does it regulate cell cycle progression?

A

The Rb protein inhibits CDK activity and promotes cell cycle arrest, helping regulate the G1 checkpoint.

62
Q

How does phosphorylation of the Rb protein regulate cell cycle progression?

A

Phosphorylation of the Rb protein by cyclin-CDK complexes inactivates it, allowing cell cycle progression.

63
Q

What is the role of cyclin E in cell cycle progression?

A

Cyclin E binds to and activates CDK2, promoting the initiation of DNA replication in S phase.

64
Q

What happens during the G1 phase of the cell cycle?

A

During G1, the cell grows and carries out normal metabolic activities, and checkpoint controls ensure that the cell has enough resources and energy to begin DNA replication in S phase.

65
Q

What is the restriction point in the G1 phase?

A

The restriction point is the point in G1 where the cell commits to entering S phase, and is regulated by the Rb protein.

66
Q

How does the cell transition from G1 to S phase?

A

The transition from G1 to S phase is driven by the activation of cyclin E-CDK2 complexes, which phosphorylate target proteins and initiate DNA replication.

67
Q

What is the role of the MCM complex in DNA replication?

A

The MCM complex is a helicase that unwinds and separates the two strands of DNA during S phase.

68
Q

What is the role of DNA polymerase in DNA replication?

A

DNA polymerase synthesizes new complementary strands of DNA during S phase.

69
Q

What is the outcome of DNA replication during S phase?

A

The outcome of DNA replication is two identical copies of the chromosome, called sister chromatids, which are separated during mitosis.

70
Q

How is the accuracy of DNA replication ensured during S phase?

A

The accuracy of DNA replication is ensured by checkpoint controls, which detect and repair errors in DNA replication.

71
Q

What happens when a cell senses DNA damage?

A

When a cell senses DNA damage, it activates checkpoint controls to halt the cell cycle and initiate DNA repair mechanisms.

72
Q

What are the checkpoint controls that are activated in response to DNA damage?

A

The checkpoint controls that are activated in response to DNA damage include the G1 checkpoint, G2 checkpoint, and spindle checkpoint.

73
Q

What is the purpose of checkpoint controls in response to DNA damage?

A

The purpose of checkpoint controls in response to DNA damage is to prevent DNA replication or cell division until the damage has been repaired.

74
Q

What are some common causes of DNA damage?

A

Some common causes of DNA damage include environmental toxins, radiation, and errors in DNA replication.

75
Q

What are the pathways that are activated in response to DNA damage?

A

The pathways that are activated in response to DNA damage include the ATM-CHK2 pathway and the ATR-CHK1 pathway.

76
Q

What is the ATM-CHK2 pathway?

A

The ATM-CHK2 pathway is activated in response to double-strand breaks in DNA, and helps prevent cell cycle progression by inhibiting CDK activity and promoting cell cycle arrest.

77
Q

What is the ATR-CHK1 pathway?

A

The ATR-CHK1 pathway is activated in response to single-stranded DNA breaks, and helps prevent cell cycle progression by inhibiting CDK activity and promoting DNA repair.

78
Q

What is the role of the p53 tumor suppressor gene in response to DNA damage?

A

The p53 tumor suppressor gene helps prevent uncontrolled cell division by promoting cell cycle arrest or apoptosis in response to DNA damage.

79
Q

How is the activity of p53 regulated in response to DNA damage?

A

The activity of p53 is regulated by phosphorylation and stabilization, which promote its activity in response to DNA damage.

80
Q

What are the consequences of a failure to repair DNA damage?

A

A failure to repair DNA damage can lead to mutations, chromosomal abnormalities, and an increased risk of cancer.

81
Q

What is the DNA damage response?

A

The DNA damage response is a complex set of cellular processes that are activated in response to DNA damage to prevent the transmission of damaged DNA to daughter cells.

82
Q

What are the common types of DNA damage?

A

The common types of DNA damage include single-strand breaks, double-strand breaks, and base damage.

83
Q

What are the consequences of DNA damage?

A

DNA damage can lead to mutations, chromosomal abnormalities, and an increased risk of cancer.

84
Q

What are the processes involved in the DNA damage response?

A

The processes involved in the DNA damage response include checkpoint controls, DNA repair mechanisms, and apoptosis.

85
Q

What are checkpoint controls in the DNA damage response?

A

Checkpoint controls help prevent cell cycle progression until DNA damage has been repaired, and are activated by the ATM-CHK2 and ATR-CHK1 pathways.

86
Q

What are the DNA repair mechanisms in the DNA damage response?

A

The DNA repair mechanisms in the DNA damage response include base excision repair, nucleotide excision repair, and double-strand break repair.

87
Q

What is base excision repair?

A

Base excision repair is a DNA repair mechanism that repairs single-strand breaks and base damage.

88
Q

What is nucleotide excision repair?

A

Nucleotide excision repair is a DNA repair mechanism that repairs damage to DNA caused by ultraviolet radiation and other environmental factors.

89
Q

What is double-strand break repair?

A

Double-strand break repair is a DNA repair mechanism that repairs double-strand breaks by homologous recombination or non-homologous end joining.

90
Q

What is apoptosis in the DNA damage response?

A

Apoptosis is a programmed cell death mechanism that is activated in response to severe DNA damage to prevent the transmission of damaged DNA to daughter cells.

91
Q

What is replication stress?

A

Replication stress is a condition where DNA replication is disrupted or slowed down, leading to DNA damage and activation of the DNA damage response.

92
Q

What are the common causes of replication stress?

A

The common causes of replication stress include DNA damage, nucleotide depletion, and defects in DNA replication machinery.

93
Q

What are the consequences of replication stress?

A

Replication stress can lead to DNA damage, chromosomal abnormalities, and an increased risk of cancer.

94
Q

What is the major pathway for sensing and signaling repair mechanisms in response to replication stress?

A

The major pathway for sensing and signaling repair mechanisms in response to replication stress is the ATR-CHK1 pathway.

95
Q

What is the ATR-CHK1 pathway?

A

The ATR-CHK1 pathway is a DNA damage response pathway that is activated in response to replication stress and helps prevent cell cycle progression until DNA damage has been repaired.

96
Q

What is the role of ATR in the ATR-CHK1 pathway?

A

ATR is a protein kinase that is activated in response to replication stress, and helps prevent cell cycle progression by inhibiting CDK activity and promoting DNA repair.

97
Q

What is the role of CHK1 in the ATR-CHK1 pathway?

A

CHK1 is a protein kinase that is activated by ATR, and helps prevent cell cycle progression by inhibiting CDK activity and promoting DNA repair.

98
Q

What are the downstream targets of CHK1 in the ATR-CHK1 pathway?

A

The downstream targets of CHK1 in the ATR-CHK1 pathway include CDC25A, which is a phosphatase that activates CDK activity, and replication protein A (RPA), which is involved in DNA replication and repair.

99
Q

How is the ATR-CHK1 pathway regulated in response to replication stress?

A

The ATR-CHK1 pathway is regulated by multiple factors, including the activity of ATR and CHK1, as well as the availability of nucleotides and other factors required for DNA replication.

100
Q

What are some therapeutic strategies for targeting replication stress in cancer cells?

A

Therapeutic strategies for targeting replication stress in cancer cells include inhibiting ATR, CHK1, or other factors in the ATR-CHK1 pathway, as well as combining these inhibitors with DNA-damaging agents to enhance DNA damage and apoptosis.

101
Q

What is the mitotic spindle checkpoint?

A

The mitotic spindle checkpoint is a cell cycle checkpoint that ensures that chromosomes are properly aligned and attached to spindle fibers before the cell enters anaphase.

102
Q

What is the purpose of the mitotic spindle checkpoint?

A

The purpose of the mitotic spindle checkpoint is to prevent chromosomal abnormalities and ensure that daughter cells receive the correct number of chromosomes during cell division.

103
Q

What is the role of the kinetochore in the mitotic spindle checkpoint?

A

The kinetochore is a protein complex that is responsible for attaching chromosomes to spindle fibers and is involved in the mitotic spindle checkpoint.

104
Q

How is the mitotic spindle checkpoint activated?

A

The mitotic spindle checkpoint is activated by the presence of unattached or improperly attached chromosomes, which generates a signal that halts cell cycle progression.

105
Q

What are the proteins involved in the mitotic spindle checkpoint?

A

The proteins involved in the mitotic spindle checkpoint include MAD1, MAD2, BUB1, BUB3, and the anaphase-promoting complex (APC).

106
Q

What is the role of MAD1 and MAD2 in the mitotic spindle checkpoint?

A

MAD1 and MAD2 are checkpoint proteins that help monitor the attachment of chromosomes to spindle fibers and generate a signal to halt cell cycle progression if attachment is improper.

107
Q

What is the role of BUB1 and BUB3 in the mitotic spindle checkpoint?

A

BUB1 and BUB3 are checkpoint proteins that help activate the mitotic spindle checkpoint by recruiting and activating MAD1 and MAD2.

108
Q

What is the role of the APC in the mitotic spindle checkpoint?

A

The APC is an enzyme that helps regulate the transition from metaphase to anaphase by degrading cyclins and other regulatory proteins.

109
Q

How is the activity of the APC regulated in the mitotic spindle checkpoint?

A

The activity of the APC is regulated by the spindle checkpoint, which ensures that all chromosomes are properly attached to spindle fibers before the cell enters anaphase.

110
Q

What are the consequences of a failure in the mitotic spindle checkpoint?

A

A failure in the mitotic spindle checkpoint can lead to chromosomal abnormalities, aneuploidy, and an increased risk of cancer.