cell cycle Flashcards
(110 cards)
1
Q
What happens during prophase in mitosis?
A
Chromosomes condense and become visible, the nuclear envelope breaks down, and spindle fibers form.
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.
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.
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.
5
Q
What happens during telophase in mitosis?
A
Chromosomes reach opposite poles and begin to decondense, and nuclear envelopes start to reform.
6
Q
What is cytokinesis in mitosis?
A
It is the division of the cytoplasm, usually beginning during telophase.
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.
8
Q
What happens during the G1 phase of interphase?
A
The cell grows and carries out normal metabolic activities.
9
Q
What happens during the S phase of interphase?
A
DNA replication occurs.
10
Q
What happens during the G2 phase of interphase?
A
The cell prepares for mitosis by synthesizing proteins and organelles.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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).
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.
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.
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.
25
What happens during the G2 phase?
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.
26
What is the duration of G2 phase?
The duration of G2 phase is typically shorter than G1 phase, ranging from a few hours to a few days.
27
What are some factors that can influence the duration of G2 phase?
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.
28
How is the transition from G2 to mitosis regulated?
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.
29
What happens if a cell fails the G1 checkpoint?
The cell enters a non-dividing state called G0, or undergoes apoptosis (programmed cell death).
30
What happens if a cell fails the G2 checkpoint?
The cell is prevented from entering mitosis, and DNA repair mechanisms are activated to fix any damage.
31
What is S phase?
S phase is the stage in the cell cycle where DNA replication occurs.
32
When does S phase occur in the cell cycle?
S phase occurs between the gap phases G1 and G2 and precedes mitosis.
33
What happens during S phase?
During S phase, DNA helicase unwinds and separates the two strands of DNA, and DNA polymerase synthesizes new complementary strands.
34
How is DNA replication initiated in S phase?
DNA replication is initiated at multiple sites on the chromosome called origins of replication.
35
What is the direction of DNA synthesis during S phase?
DNA synthesis occurs in a 5' to 3' direction, adding nucleotides to the 3' end of the new strand.
36
How are the newly synthesized DNA strands separated during S phase?
The two newly synthesized DNA strands are separated by topoisomerases, which relieve tension in the double helix.
37
What is the outcome of DNA replication during S phase?
The outcome of DNA replication is two identical copies of the chromosome, called sister chromatids, which are separated during mitosis.
38
How is the accuracy of DNA replication ensured during S phase?
The accuracy of DNA replication is ensured by checkpoint controls, which detect and repair errors in DNA replication.
39
What are some factors that can disrupt DNA replication during S phase?
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.
40
What is the duration of S phase?
The duration of S phase varies depending on the cell type, but typically lasts for several hours to complete the replication of all chromosomes.
41
What are the key players in regulating the cell cycle?
The key players in regulating the cell cycle include cyclins, cyclin-dependent kinases (CDKs), tumor suppressor genes, and proto-oncogenes.
42
What are cyclins?
Cyclins are proteins that are produced and degraded in a cell cycle-dependent manner, and they regulate the activity of CDKs.
43
What are CDKs? cyclin-dependent kinases (CDKs)
CDKs are enzymes that phosphorylate target proteins to drive cell cycle progression.
44
How do cyclins and CDKs interact to regulate the cell cycle?
Cyclins bind to and activate CDKs, allowing them to phosphorylate target proteins and drive cell cycle progression.
45
What is the role of tumor suppressor genes in the cell cycle?
Tumor suppressor genes help prevent uncontrolled cell division by inhibiting the activity of CDKs or promoting cell cycle arrest.
46
What is the role of the p53 tumor suppressor gene in the cell cycle?
The p53 tumor suppressor gene helps prevent uncontrolled cell division by promoting cell cycle arrest or apoptosis in response to DNA damage.
47
What is the role of proto-oncogenes in the cell cycle?
Proto-oncogenes promote cell cycle progression by activating CDKs or stimulating the production of cyclins.
48
What happens if proto-oncogenes become mutated and become oncogenes?
If proto-oncogenes become mutated and become oncogenes, they can promote uncontrolled cell division and contribute to the development of cancer.
49
What is the role of checkpoint controls in the cell cycle?
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
How are checkpoint controls activated in the cell cycle?
Checkpoint controls are activated by DNA damage or incomplete processes, which halt the cell cycle until the issues are resolved.
51
What is the role of the retinoblastoma (Rb) protein in the cell cycle?
The Rb protein helps regulate the G1 checkpoint by inhibiting CDK activity and promoting cell cycle arrest.
52
How is the Rb protein regulated in the cell cycle?
The Rb protein is regulated by cyclin-CDK complexes, which phosphorylate and inactivate it, allowing cell cycle progression.
53
What is the role of the anaphase-promoting complex (APC) in the cell cycle?
The APC helps regulate the transition from metaphase to anaphase by degrading cyclins and other regulatory proteins.
54
How is the activity of APC regulated in the cell cycle?
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
What are some factors that can disrupt the normal regulation of the cell cycle?
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
What are the signaling pathways involved in cell cycle progression?
The signaling pathways involved in cell cycle progression include growth factor signaling, extracellular matrix signaling, and the Ras-Raf-MEK-ERK pathway.
57
How does growth factor signaling promote cell cycle progression?
Growth factors bind to cell surface receptors, activating intracellular signaling pathways that stimulate the production of cyclins and activate CDKs.
58
What is the role of extracellular matrix signaling in cell cycle progression?
Extracellular matrix signaling regulates cell adhesion, migration, and survival, which can influence cell cycle progression.
59
How does the Ras-Raf-MEK-ERK pathway promote cell cycle progression?
The Ras-Raf-MEK-ERK pathway promotes cell cycle progression by stimulating the production of cyclins and activating CDKs.
60
What is the role of cyclin D in cell cycle progression?
Cyclin D binds to and activates CDK4 and CDK6, promoting the phosphorylation and inactivation of the Rb protein.
61
What is the Rb protein and how does it regulate cell cycle progression?
The Rb protein inhibits CDK activity and promotes cell cycle arrest, helping regulate the G1 checkpoint.
62
How does phosphorylation of the Rb protein regulate cell cycle progression?
Phosphorylation of the Rb protein by cyclin-CDK complexes inactivates it, allowing cell cycle progression.
63
What is the role of cyclin E in cell cycle progression?
Cyclin E binds to and activates CDK2, promoting the initiation of DNA replication in S phase.
64
What happens during the G1 phase of the cell cycle?
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
What is the restriction point in the G1 phase?
The restriction point is the point in G1 where the cell commits to entering S phase, and is regulated by the Rb protein.
66
How does the cell transition from G1 to S phase?
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
What is the role of the MCM complex in DNA replication?
The MCM complex is a helicase that unwinds and separates the two strands of DNA during S phase.
68
What is the role of DNA polymerase in DNA replication?
DNA polymerase synthesizes new complementary strands of DNA during S phase.
69
What is the outcome of DNA replication during S phase?
The outcome of DNA replication is two identical copies of the chromosome, called sister chromatids, which are separated during mitosis.
70
How is the accuracy of DNA replication ensured during S phase?
The accuracy of DNA replication is ensured by checkpoint controls, which detect and repair errors in DNA replication.
71
What happens when a cell senses DNA damage?
When a cell senses DNA damage, it activates checkpoint controls to halt the cell cycle and initiate DNA repair mechanisms.
72
What are the checkpoint controls that are activated in response to DNA damage?
The checkpoint controls that are activated in response to DNA damage include the G1 checkpoint, G2 checkpoint, and spindle checkpoint.
73
What is the purpose of checkpoint controls in response to DNA damage?
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
What are some common causes of DNA damage?
Some common causes of DNA damage include environmental toxins, radiation, and errors in DNA replication.
75
What are the pathways that are activated in response to DNA damage?
The pathways that are activated in response to DNA damage include the ATM-CHK2 pathway and the ATR-CHK1 pathway.
76
What is the ATM-CHK2 pathway?
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
What is the ATR-CHK1 pathway?
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
What is the role of the p53 tumor suppressor gene in response to DNA damage?
The p53 tumor suppressor gene helps prevent uncontrolled cell division by promoting cell cycle arrest or apoptosis in response to DNA damage.
79
How is the activity of p53 regulated in response to DNA damage?
The activity of p53 is regulated by phosphorylation and stabilization, which promote its activity in response to DNA damage.
80
What are the consequences of a failure to repair DNA damage?
A failure to repair DNA damage can lead to mutations, chromosomal abnormalities, and an increased risk of cancer.
81
What is the DNA damage response?
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
What are the common types of DNA damage?
The common types of DNA damage include single-strand breaks, double-strand breaks, and base damage.
83
What are the consequences of DNA damage?
DNA damage can lead to mutations, chromosomal abnormalities, and an increased risk of cancer.
84
What are the processes involved in the DNA damage response?
The processes involved in the DNA damage response include checkpoint controls, DNA repair mechanisms, and apoptosis.
85
What are checkpoint controls in the DNA damage response?
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
What are the DNA repair mechanisms in the DNA damage response?
The DNA repair mechanisms in the DNA damage response include base excision repair, nucleotide excision repair, and double-strand break repair.
87
What is base excision repair?
Base excision repair is a DNA repair mechanism that repairs single-strand breaks and base damage.
88
What is nucleotide excision repair?
Nucleotide excision repair is a DNA repair mechanism that repairs damage to DNA caused by ultraviolet radiation and other environmental factors.
89
What is double-strand break repair?
Double-strand break repair is a DNA repair mechanism that repairs double-strand breaks by homologous recombination or non-homologous end joining.
90
What is apoptosis in the DNA damage response?
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
What is replication stress?
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
What are the common causes of replication stress?
The common causes of replication stress include DNA damage, nucleotide depletion, and defects in DNA replication machinery.
93
What are the consequences of replication stress?
Replication stress can lead to DNA damage, chromosomal abnormalities, and an increased risk of cancer.
94
What is the major pathway for sensing and signaling repair mechanisms in response to replication stress?
The major pathway for sensing and signaling repair mechanisms in response to replication stress is the ATR-CHK1 pathway.
95
What is the ATR-CHK1 pathway?
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
What is the role of ATR in the ATR-CHK1 pathway?
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
What is the role of CHK1 in the ATR-CHK1 pathway?
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
What are the downstream targets of CHK1 in the ATR-CHK1 pathway?
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
How is the ATR-CHK1 pathway regulated in response to replication stress?
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
What are some therapeutic strategies for targeting replication stress in cancer cells?
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
What is the mitotic spindle checkpoint?
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
What is the purpose of the mitotic spindle checkpoint?
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
What is the role of the kinetochore in the mitotic spindle checkpoint?
The kinetochore is a protein complex that is responsible for attaching chromosomes to spindle fibers and is involved in the mitotic spindle checkpoint.
104
How is the mitotic spindle checkpoint activated?
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
What are the proteins involved in the mitotic spindle checkpoint?
The proteins involved in the mitotic spindle checkpoint include MAD1, MAD2, BUB1, BUB3, and the anaphase-promoting complex (APC).
106
What is the role of MAD1 and MAD2 in the mitotic spindle checkpoint?
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
What is the role of BUB1 and BUB3 in the mitotic spindle checkpoint?
BUB1 and BUB3 are checkpoint proteins that help activate the mitotic spindle checkpoint by recruiting and activating MAD1 and MAD2.
108
What is the role of the APC in the mitotic spindle checkpoint?
The APC is an enzyme that helps regulate the transition from metaphase to anaphase by degrading cyclins and other regulatory proteins.
109
How is the activity of the APC regulated in the mitotic spindle checkpoint?
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
What are the consequences of a failure in the mitotic spindle checkpoint?
A failure in the mitotic spindle checkpoint can lead to chromosomal abnormalities, aneuploidy, and an increased risk of cancer.
