Cell Cycle, Mitosis, and Meiosis Flashcards
1
Q
Abnormal number of chromosomes in a cell
A
aneuploidy
2
Q
Four phases of the cell cycle
A
G1, S, G2, M
3
Q
Resting phase of the cell cycle
A
G0
4
Q
What is the committed phase of the cell cycle? (no going back)
A
S phase
5
Q
Phase which comprises the largest segment of the cell cycle?
A
G1 phase
6
Q
Early cell divisions of embryos proceed without which two phases
A
G1 or G2
7
Q
Which phase of the cell cycle sees organelles replicated
A
G2 phase
8
Q
Kinase activity during late G1/S that prevents re-initiation of replication
A
CDK2 / Cyclin A
9
Q
What prepares the Origin Recognition Complex for initiating replication during late G1?
A
MCM helicase
10
Q
After what does the animal cell no longer need growth factors continue with the cycle?
A
Restriction point (in G1)
11
Q
Activate components of pathways responsible for DNA synthesis and even mitosis
A
Cyclin dependent kinases (CDK)
12
Q
Regulate activity of cyclin dependent kinases
A
Cylcins
13
Q
Provide additional cell cycle control in specific situations (eg absence of growth signals or the presence of DNA damage)
A
Cdk inhibitors
14
Q
Quality control checks preventing progression in the presence of errors in the cell cycle. Can initiate apoptosis
A
checkpoints
15
Q
The transition from G2 to M is regulated by…
A
Mitosis Promoting Factor (MPF)
16
Q
Mutated protein kinases which inhibit the cell cycle
A
Cell division cycle (CDC) mutants
17
Q
Components of the MPF complex
A
CDK1 and cyclin B
18
Q
Adds the activating phosphate to CDK1
A
CDK Activating Kinase (CAK)
19
Q
Adds the inhibitory phosphate to CDK1
A
Wee1 kinase
20
Q
Removes inhibitory phosphate from CDK1
A
Cdc25 Phosphatase
21
Q
Initiated by Cyclin B and CDK1
A
M phase
22
Q
Ubiquinates cyclin B for degradation
A
APC
23
Q
This CDK can be a placeholder for all others
A
CDK1
24
Q
How do cyclins control CDKs?
A
Determine the target specificity
25
CDK/Cyclin combination active in Early G1 through R
Cdk4, 6 and Cyclin D
26
CDK/Cyclin combination active from G1 to S transition
Cdk2 and Cyclin E
27
CDK/Cyclin combination active from G2 to M transition
Cdk1 and Cyclin B
28
Four mechanisms of Cdk regulation
1) association of Cdks with cyclins
2) phosphorylation of Cdk
3) Dephosphorylation of Cdk
4) association with Cdk inhibitors
29
Binds CDK 4,6 and inhibits progression through G1
Ink 4 family
30
Binds Cdk2/Cyclin A or E and inhibits progress through G1 and S
Cip/Kip family
31
Growth factors binds to their receptors, initiating a signaling cascade leading to the synthesis of...
Cyclin D
32
The altered gene for this protein is responsible for retinoblastomas
Retinoblastoma protein (Rb)
33
Binds to E2F to repress transcription
Rb
34
When phosphorylated by Cdk4,6/Cyclin D,E Rb dissociates from what to activate transcription?
E2F
35
Before the restriction point, Cdk2/Cyclin E is inhibited by...
p27
36
What is initiated once Cdk2/Cyclin E is activated
DNA replication
37
As G1 progresses, more Cyclin E is synthesized. Repression by p27 is relieved in what three ways
1) p27 synthesis decreases
2) p27 binds Cdk4,6/Cyclin D
3) p27 also targeted for degradation
38
Protect the cell from replication errors or passing down damaged DNA
DNA damage checkpoints
39
Ensures chromosomes are aligned properly so each daughter cell receives one copy of each chromosome
Spindle assembly checkpoint
40
Three DNA damage checkpoints
1) G1 phase - ensures cell does not proceed to S phase with damaged DNA
2) S phase continuously monitors for errors in replication and DNA damage
3) G2 phase - final monitor for DNA damage before segregation of the chromosomes in M phase
41
Checkpoint monitoring the alignment of chromosomes on the metaphase plate. What phase is this in?
M phase
42
Kinase part of the complex recognizing double strand DNA damage
ATM
43
Kinase part of the complex recognizing single strand DNA damage
ATR
44
ATM kinase phosphorylates which downstream kinase in DNA damage checkpoints
ChK2
45
ATR kinase phosphorylates which downstream kinase in DNA damage checkpoints
ChK1
46
Chk1 and Chk2, both tumor suppression genes, phosphorylate what to continue DNA damage checkpoint pathway?
Cdc25
47
What happens when Cdc25 is phosphorylated
Cdc25 is unable to activate Cdk1 and Cdk2
48
Which two kinases phosphorylate p53
ATM and Chk2
49
Transcription factor regulating transcription of the cyclin-dependent kinase inhibitor p21
p53
50
Inhibition target of p21
Cdk2/Cyclin E complex (causing G1 arrest)
51
[Stage of Mitosis] Chromosomes condense, initial formation of mitotic spindles, nuclear envelop breaks down
Prophase
52
[Stage of Mitosis] Spindle microtubules attach to kinetochore, chromosomes align at center of spindles
Metaphase
53
[Stage of Mitosis] Sister chromatids separate and move to poles
Anaphase
54
[Stage of Mitosis] Reformation of nuclear envelope, chromosome condensation
Telophase
55
Positive feedback by MPF in mitosis
MPF (CDK1/Cyclin B) phosphorylates Aurora kinase which then phosphorylates Polo-like kinase. Polo-like Kinase then phosphorylates MPF (CDK1/Cyclin B)
56
Why would chromosomes need to be condensed
to move them around
57
Why would chromosomes need to be diffuse
to allow transcription / replication / etc
58
Binds sister chromatids together side by side
Cohesin
59
Chromosomes are condensed during ____ to facilitate separation
prophase
60
Promotes condensation (of chromosomes) in a process that requires hydrolysis of ATP
Condensin complex
61
The ____ complex is a target of MPF and Aurora B
Condensin complex
62
Sister chromatids are held together by cohesin along their entire length in this phase
G2
63
Cohesin is removed from most of the length of the chromosome arms but remains at the centromere in this phase
prophase
64
Phosphorylate lamins to cause their deploymerization
MPF
65
Lamins A and C disperse to where during nuclear envelope breakdown
cytoplasm
66
Diffuse to the endoplasmic reticulum and form vesicles during nuclear envelope breakdown (2)
membrane proteins and lamin B
67
Nuclear pore complexes disperse when _____ are phosphorylated
nucleoporins
68
Attachment of chromosomes at the kinetochore
spindle formation
69
Two types of microtubules which push spindle poles apart
Polar and Astral Microtubules
70
Four Types of Microtubules in Mitosis
1) Kinetochore
2) Chromosomal
3) Polar - separates poles
4) Astral - position and orient spindle
71
Regulate assembly and disassembly of microtubules
Microtubule Associated Proteins (MAPs)
72
Drug that stabilizes the microtubules and interferes with the ability to align the chromosomes. Used in cancer
Paclitaxel (Taxol)
73
Protein complex that binds centromere and spindle microtubules
Kinetochore
74
Proteins associated with the centromere (think packaging)
Histone H3-like Centromeric Protein (CENP)
75
Tension sensor transmitting information about microtubule attachment to regulatory complex during spindle checkpoint
CENP-E
76
Four proteins in the Mitotic Checkpoint Complex (MCC)
BubR1, Bub3, Mad2, and Cdc20
77
The required activator of APC which is blocked when part of the Mitotic Checkpoint Complex
Cdc20
78
APC's activation when all chromosomes are properly oriented triggers...
anaphase
79
Destruction promotes chromosome separation by activating separase. Target of APC
Securin
80
Anaphase Promoting Complex (APC) is what sort of enzyme
ubiquitin ligase (E3 enzyme)
81
Chromosome segregation must be completed before ____ is degraded. Its degradation allow the cell to exit mitosis. Failure to complete chromosome segregation is called nondisjunction
Cyclin B
82
Anaphase A
Sister chromatid separation
83
Anaphase B
Separation of spindle poles
84
When do cyclin b levels peak
during mitosis
85
Decrease in its activity permits events of telophase and cytokinesis to proceed
MPF
86
Nuclear envelope reassembled, chromosomes decondense, and the formation of the cleavage furrow
telophase
87
Dephosphorylation by ___ promotes nuclear reassembly
Cdc14 phosphatase
88
Signal for formation of contractile ring emitted during this phase of mitosis
cytokinesis
89
Actin filaments attached to plasma membrane, active in cytokinesis
Contractile Ring
90
Interacts with the actin filaments in sliding filament mechanism to contract ring
Bipolar Myosin II
91
A transient increase in intracellular Ca2+ activates Myosin Light Chain (MLC) kinase. What does this trigger?
Contraction of the contractile ring
92
Two nuclear and cell divisions without an intervening S phase
Meiosis
93
Ploidy of haploid cells?
N
94
Ploidy of diploid cells?
2N
95
At the end of S phase when DNA synthesis is complete (meiosis), a diploid cell has a _C DNA content and is _N.
4C and 2N
96
At the end of mitosis the daughter cells are _N and have _C DNA content
2N and 2C
97
At the end of meiosis I, gametes have a _N chromosome number and _C DNA content
1N and 2C
98
At the end of meiosis II, gametes have a _N chromosome number and _C DNA content
1N and 1C
99
Exchange of genetic material between non-sister chromatids of homologous chromosomes
recombination
100
Purpose of the Synaptonemal Complex in meiosis
Hold the chromosomes together
101
First part of the synaptonemal complex to appear, lining the chromatin loops and later forming lateral elements
Axial elements
102
Zipper-like structure that holds Synaptonemal Complex together
Transverse filaments
103
Site of recombinatin in the synaptonemal complex. Contains proteins mediating this process.
Recombination nodules
104
Points of attachment of homologs. Sites of recombination. Required for proper segregation of homologous chromosomes.
Chiasmata
105
stage female meiosis arrested at before puberty and in the absence of ovulation
diplotene stage of prophase I
106
Two points of regulation for oocyte meiosis
1) Diplotene (Prophase I) -- chromosomes decondense and are transcriptionally active
2) Metaphase II arrest
107
Induces chromosome condensation, breakdown of nuclear envelope, and formation of spindle in oocyte meiosis
Cdk1/Cyclin B
108
Responsible for maintaining Cdk1 activity in oocyte meiosis. Its essential component, Mos, is synthesized in oocytes following meiosis I -- inhibits APC/C.
Cytostatic factor (CSF)
109
Fertilization results in activation of APC/C via inhibition of Cytostatic Factor (CSF) by...
Emi2/Erp1 (cyclin B degraded and the second meiotic division completes)
