Cell Division Flashcards
1
Q
_____ is the nondividing cell state
A
G0
2
Q
The ___ ____ is every other phase, other than the G0 phase. When chromosomes are duplicated and two identical, daughter cells are formed.
A
Cell cycle
3
Q
The ___ is the phase when cells decide if they can divide and commit to dividing. The point when cells commit to dividing is called ____ ___.
A
G1
Restriction point
4
Q
The ____ phase is when DNA synthesis and replication occurs. This is also the time where the centrosome is duplicated.
A
S
5
Q
The ____ phase involves verification that all DNA synthesis has been completed and includes assembling the machinery that will trigger entry into mitosis
A
G2
6
Q
The ___ phase also called ___ is when the replicated chromosomes separate into two cells
A
M
Mitosis
7
Q
____ refers to the behavior of chromosomes in dividing somatic cells. ____ is a behavior of the entire cell pinching into two daughter cells, and occurs toward the end of mitosis during telophase.
A
Mitosis
Cytokinesis
8
Q
Mitosis is divided into five stages:
1.
2.
3.
4.
5.
A
Prophase, pro metaphase, metaphase, anaphase, and telophase
9
Q
During ____ the replicated daughter centrosomes move apart, chromosomes begin to condense, and the nuclear envelope breaks down
A
Prophase
10
Q
During ____ bipolar spindles become apparent, microtubules attach to kinetichores, and chromosome/nuclear events continue
A
Prometaphase
11
Q
During ____ maximally, condensed replicated, chromosomes align in a single plane as a disk like plate
A
Metaphase
12
Q
During ______ daughter, chromatids separate from each other, and begin to move apart as individual chromosomes
A
Anaphase
13
Q
During _____ the plasma membrane begins to constrict around at the spindle midline, chromosomes begin to decondense, and the nuclear envelope begins to reform
A
Telophase
14
Q
______ encompass adjacent daughter chromatids, so that they remain attached to each other throughout G2, prophase, prometaphase, and metaphase. These proteins are proteolyzed at the onset of anaphase to allow the chromatids to segregate into two daughter cells
A
Cohesions
15
Q
In prophase, ____ are activated and are responsible for chromosome compaction. They bridge different points along DNA strands to form loops in sequential waves forming loops within loops this process reaches its peak in metaphase.
A
Condensins
16
Q
At the onset of Mphase, the duplicated centrioles, split and move apart to form the two poles of the spindle apparatus. Spindle pool movement is driven by ____ involving the motor proteins ___ and ____.
A
Microtubules
Kinesin
Dynein
17
Q
The nuclear envelope is broken down when lamin filaments (intermediate filaments) are ____ by ____, causing them to depolymerize
A
Phosphorylated
Cyclin-dependent kinase (CDK1)
18
Q
Spindle microtubules include ____ microtubules, ____ microtubules, and ____ microtubules.
A
Kinetochore
Interpolar
Astral
19
Q
A ____ is a complex of proteins that assemble on centromeric DNA. they function as attachment points for spindle microtubules. They also sense alignment of chromosomes in metaphase.
A
Kinetochore
20
Q
____ is a histone in the kinetochore composition. It defines centromeric chromatin, and mediates binding of kinetochores to DNA.
A
CENP-A
21
Q
The ______ complex of Kinetochore permits tubulin polymerization and D polymerization to occur while continuing to maintain microtubule – kinetochore coupling.
A
Ndc80
22
Q
The ____ end of the microtubule directs motor proteins to push chromosomes away from the spindle poles
A
+
23
Q
_____ of microtubules at the kinetochore pulls chromosomes toward the spindle pole.
A
Depolymerization
24
Q
Microtubule ____, where, in tubulin subunits are removed at the ___ end, can also pull microtubules and attach to chromosomes to towards the pole.
A
25
_______ is activated at the metaphase – anaphase transition. Cdc20 is an activator of this complex. Together they tag securin for destruction. Securin is an inhibitor of ______ . Activated ____ is released which hydrolyzes cohesin and promotes daughter chromatid separation.
APC/C anaphase promoting complex, a ubiquitin ligase complex
Separase
Separase
26
In addition to cohesins, the protein _______ helps maintain sister chromosome attachment, particularly in the centromere region, preventing premature separation prior to anaphase
SGO (shugoshin)
27
During anaphase, there is an initial movement of chromosomes to the ____, due to a net balance of push and pull. Overlapping _____ microtubules push against each other via motor proteins and the spindles elongate. The initial kinetochore and spindle pole mediated movements are referred to as anaphase ___. The subsequent spindle elongation is referred to as anaphase ____.
Poles
Interpolar
A
B
28
During _____, a Central spindle assembly forms at the overlap of interpolar and astral microtubules. This assembly recruits and activates ______, which re-organizes actin microfilaments to form a contractile ring of actin and myosin under the plasma membrane. Contraction is initiated, pinching the cell into two daughter cells.
Cytokinesis
RhoA
29
The result of spindle defects in mitosis is usually _____, meaning the daughter cells have an abnormal number of chromosomes
Aneuploidy
30
31
Signals from both outside and inside, the cell are integrated to regulate proliferation. ____ ____ provide very strong signals promoting proliferation and get cells past the restriction point. ___ ____ are no longer required past the restrictive point (R).
Growth factors
Growth factors
32
Cell cycle control systems are generally ____ (on/off) and launch events in an irreversible manner.
Binary
33
One major cell cycle controller is phosphorylation and dephosphorylation events carried out by _______ _____. Another major cell cycle controller regulated proteolysis which is carried out by ____ and ____ (ubiquitin ligase complexes).
Cyclin-dependent kinases (CDKs)
APC/C
SCF
34
CDKs are regulated by _____, which lack enzymatic activity, but help control, CDK activity and target selection. ____ are proteins that can inhibit CDK activity.
Cyclins
CKIs cyclin-dependent kinase inhibitors
35
Different pairs of cyclines/CDKs Drive different stages of the cell cycle. The decision to pass the restriction point involves ______. S phase on set and progression involves cyclines ____ and ____. Entry into M phase involves cyclin ____.
G1-CDK
G1/S-CDK and S-CDK
M-CDK
36
Most ____ are destroyed at the end of the preceding phase via a ubiquitin ligase complex, therefore the first part of G1 is a period with very low ____ activity.
Cyclines
CDK
37
Growth factors and other signals, as well as lack of DNA damage, trigger the synthesis of _____ __, which then promotes the activation of ____. This further activates more transcription factors that drive the expression of proteins that push the cell through ____.
Cyclin D
G1 CDK
R
38
Another process that pushes the cell past R is the Ubiquitin ligase complex, ____, which triggers the destruction of ___ ____, removing this potential inhibition to full CDK activation.
SCF
G1 CKIs
39
Cyclin _____ induces gene transcription for cyclin ____ and ____, which together with CDK2 push a cell into and through S phase respectively.
D
E
A
40
Growth factor mitogen binds to the tyrosine kinase family of growth factor receptors, _____. This activates Ras G proteins which then activates the ____ ____ pathway.
RTKs
MAP kinase (MAPK)
41
The MAP kinase pathway consists of three sequential kinases that function as a cascade. ______ phosphorylates _____, which phosphorylates ____.
MAPKKK
MAPKK
MAPK
42
activated MAPK enters the _____ and phosphorylates and activates transcriptional regulators that are associated with immediate response genes comprising a first wave of transcriptional response
Nucleus
43
The immediate response genes in the first wave, encode more transcription factors and regulators that produce a ____ _____ of transcription, producing delayed response gene products important in cell cycle advancement including cyclin D.
Second wave
44
Cyclin D binds to CDK2, forming G1-CDK, which triggers a ___ ____ of gene expression by phosphorylating and inhibiting the _____ protein. This protein is an inhibitor of the _____ family of transcription factors. These transcription factors are then activated. proteins needed for DNA replication and entry into S phase, including cyclin ____ and ___ are produced.
Third wave
Retinoblastoma (pRb)
E2F
E
A
45
In S phase, DNA synthesis is triggered by making ___ __ ____ competent to replicate DNA and by activating _____ activity.
Origins of replication
Helicase
46
In early G1, Mcm helicases are loaded onto origin recognition complexes ____ by accessory proteins, _____ the ORCs to become active later in S phase. Mcm helicases can only bind and license ORCs under conditions of very low ____ activity. The _____ of CDK inhibits the binding of these helicases to origins of replication.
ORCs
Licensing
CDK
Phosphorylation
47
Binding of helicases to origins of replication early in G1 results, in the formation of a ________ _____, which triggers DNA replication, and entrance into the S phase.
Pre-replicative complex (Pre-RC)
48
When helicases leave the ORCs, they are ______ them. During the rest of the cell cycle _____ and _____ suppress rebinding of Mcm helicases to ORCs, thereby preventing licensing from reoccurring until M phase is complete
De-licensing
S-Cdk
M-Cdk
49
In M phase, the _____ ____ _____ is activated by M-Cdk activity which tags and targets all ______ for proteosomal destruction. This abolishes ____ activity and allows ORCs to become de-phosphorylated, allowing Mcm helicases and associated proteins to bind ORCs early in G1, forming _____, once again, licensing the ORCs in each daughter cell. ______ is turned off later in G1 allowing cyclin accumulation, and S Cdk activation, repeating the cycle.
Ubiquitin ligase APC/C
Cyclin
CDK
PreRCs
APC/C
50
PreRCs should only be assembled ____ per cell cycle to ensure that DNA is replicated only ___ per cycle.
Once
Once
51
_____ ____ is synthesized and accumulates throughout S and G2. _____ ___ binds to CDK 1 and M- Cdk. M-Cdk is _____ at both activating and inhibiting sites by ____ and _____ kinases, respectively, resulting in very low activity. M-Cdk activation occurs through the activation of ____ _____, which removed the inhibitory phosphate. The phosphatase activity of Cdc25 is _____ by Phosphorylation of M-Cdk and the activity of the inhibitory Wee1 kinase is _____ by phosphorylation of M-Cdk. This comprises ____ ____ feedback loops, which lead to a switch like activation of M-Cdk, triggering the sudden onset of _____ phase.
Cyclin B
Cyclin B
Phosphorylated
CAK
Wee1
Cdc25 phosphatase
Enhanced
Inhibited
Double positive
M- phase
52
The functions of _____ drive a cell from G2 into M. To progress beyond metaphase the cell must then inactivate _____.
M-Cdk
M-Cdk
53
M-Cdk phosphorylates _____ to condense chromosomes, _____ _____ to increase dynamic behavior of microtubules and assemble spindles, _____ ___ _____ and ____ to facilitate nuclear envelope disassembly, _____, and proteins associated with ____ and _____ to promote their fragmentation.
Condensins
Centrosomal proteins
Nuclear pore complexes and lamins
APC/C
Golgi and ER
54
Anaphase promoting complex/cyclosome ______ is a ubiquitin ligase that tags _____ and _____ for proteosomal destruction.
APC/C
Securin
Cyclins
55
M-Cdk ____ APC/C which allows the binding of an activator protein _____. APC/C then targets securin, the destruction of securin liberates active _____ which initiates anaphase by destroying cohesins.
Phosphorylates
Cdc20
Separase
56
APC/C also targets cyclins for destruction which constitutes a _____ feedback loop where M-Cdk leads to its own inactivation via activation of APC/C.
Negative
57
Inactivation of M-Cdk is necessary for a cell to leave Mphase, a process called ____ ___.
Mitotic exit
58
The destruction of cyclins abolishes Cdk activity, and _____ _____ activities then dephosphorylate Cdk target proteins, reversing all of the CDK affects. Destruction of mitotic cyclins is necessary to ___ the cell.
Endogenous phosphatase
Reset
59
_______ is used in cell cycle control because it can completely inactivate a protein and it is not reversible, thereby provides directionality to the cell cycle.
Proteolysis
60
Protease activity destroys _____ to initiate entrance into Sphase. It destroys _____ to initiate anaphase. It destroys _____ to initiate mitotic exit.
CKI p27
Securin
Cyclin B
61
The three cell cycle checkpoints are ___, ___, and ___. Cell cycle progression is halted if things are not going well at these points.
G1/S
G2/M
M
62
The G2/M checkpoint ensures that all DNA is _____. The M checkpoint ensures that all chromosomes are attached to the ____ and lined up at the center
Replicated
Spindle
63
_____ is an important transcription factor involved in cell cycle checkpoints. It it sensitive to DNA damage. If DNA damage occurs ____ can upregulate CKI p21, halting cell cycle progression. It can also upregulate _____, a pro-apoptotic protein if DNA damage is unrepairable. p53 is a powerful ____ suppressor.
p53
p53
Bax
Tumor
64
Under healthy conditions, p53 upregulates ______, which is a ubiquitin ligase that targets p53 for destruction. This is a _____ feedback loop whereby p53 limits its own quantity.
Mdm2
Negative
65
DNA damage results in the activation of ___ and ____ kinases, which bind to damaged DNA and then activate ____ and ____ checkpoint kinases. ____ and ____ phosphorylate p53, which reduces it’s binding to Mdm2, allowing p53 quantity in the cell to rapidly rise.
ATM and ATR
Chk1 and Chk2
Chk1 and Chk2
66
p53 acts as a transcription factor turning on the expression of genes coding for _____, which arrests the cell cycle allowing time for the cell to repair damaged DNA.
CKIs
67
Open kinetochores block ____ ____ by serving as a signal for the assembly of a protein complex that binds Cdc20, preventing its binding to APC/C (inactive), halting the cell cycle.
Mitotic exit
68
____ is the spindle assembly checkpoint
SAC
69
Genes encoding proteins that stimulate proliferation are called ____. Genes that inhibit proliferation are called _____ ____ genes. In cancer gain of function, mutations are seen in ____ and loss of function Mutations are seen in ___ ___.
Oncogenes
Tumor suppressor
Oncogenes
tumor suppressor
70
Many cells tend to stop proliferating as a gene progresses in a process called _____. This is a result of various internal and external stimuli, including DNA damage, telomere shortening, oncogenic activation, radiation, oxidative stress, etc.
Senescence
71
Senescence is more complex than just a resting or dismantling the cell cycle machinery, senescent cells undergo specific changes in gene expression patterns and display a specialized phenotype called the ________ _____ ____ or _____. This can promote tissue repair, recruit immune cells, and modulate cell programming during development. However, it can also promote chronic inflammation and facilitate cancer progression.
Senescence associated secretory phenotype or SASP
72
73
_____ reduces the number of chromosomes in each gamete from 2 sets of 22 to a single set of 22 (haploid). They progress from diploid to tetraploid to diploid to haploid
Meiosis
74
The same chromosome from each parent are called _____. They are similar, not identical
Homologs
75
Replication of chromosome in S phase produces two _____, which are essentially genetically identical.
Chromatids
76
____ = the number of homologs represented, will normally be 2 in mitotic cells, 1 or 2 in meiotic cells
____ = total number of copies of a chromosome present
N
C
77
One S phase followed by two M phases results in a cell with ____ number of chromosomes.
Haploid
78
The two Mphase of meiosis are called _____ and _____.
Meiosis I and Meiosis II
79
Pairing of homologous chromosomes occurred in ______. This facilitates homologous recombination (crossing over).
Prophase I
80
______ is the process of homologous chromosome pairs binding via synaptonemal complexes.
Synapsis
81
____ ____ form between chromatids of different homologous on average at 2 to 3 locations per chromosome pair
Recombination nodules
82
The end result of homologous recombination is the chromatid contains the same ____ of genes but has either a _____ origin or ____ origin.
Sequence
Maternal
Paternal
83
_____ ______ is the random distribution of paternal and maternal homologs to the two daughter cells. Thus in meiosis, each daughter cell receives a different mix of replicated and recombinant homologs
Independent assortment
84
In meiosis I, the _____ that form at sites of recombination help hold the homologous pair (XX) together.
Chiasma
85
The protein _____ protects the centromeric cohesions from being digested by Separase during meiosis I. During metaphase II _____ is dislodged and Separase destroys ______ , allowing the separation of chromatids
Shugoshin
Shugoshin
Cohesions
86
____ is the failure of chromosomes to separate. This can occur in meiosis I or II. Results in monosomies or trisomies
Nondisjunction
87
Down syndrome is _____ _, Edward syndrome is ___ _, and patau syndrome is ____ __.
Trisomy 21
Trisomy 18
Trisomy 13
88
Non-disjunction can also occur during mitotic divisions in the embryo, resulting in a genetically _______ individual.
Chimeric (mosaic)
89
Autosomal _____ usually arise by nondisjunction during meiosis I of oogenesis.
Trisomies
90
_____ disjunction is the most common type of paternal nondisjunction event.
XY
91
_____ ____ ____ are cells in embryos that have become committed to eventually undergoing meiosis and forming gametes
Primordial Germ Cells (PGCs)
92
93
94
95
Primordial germ cells in the gonads become highly proliferative and differentiate into ____ and ____. Once these enter the first meiotic division they are called _____ _____ and ____ ____
Spermatogonia and oogonia
Primary spermatocytes and primary oocytes
96
Completion of meiosis II forms haploid ____ in males and ____ in females
Spermatids
Ovum
97
The _____ gene on the Y chromosome drives gonads to develops into testes. The absence of this gene leads to the formation of ovaries.
SRY
98
In primordial germ cells, certain genes are epigenetically modified in a process called ______. This involves DNA methylation.
Imprinting
99
_____ occurs in males. Spermatogonia increase in numbers during fetal developed and then become dormant. At puberty, _____ is onset and Spermatogonia undergo mitotic division.
Spermatogenesis
Spermatogenesis
100
In females, _______ arrests cells in their primary oocyte state. They remain arrested in ______ until puberty.
Prophase I
Prophase I
101
A singular gene has two versions called ______. If the two alleles are the same they are called ______. If the two alleles are different they are called ____.
Alleles
Homozygous
Heterozygous
102
_____ is what we see. The ____ is the actual generic variants (alleles).
Phenotype
Genotype
103
If there are two different alleles present, the visible allele is the ____ one.
Dominant
104
_____ gene pairs assort independently at meiosis.
Unlinked
105
______ gene disorders often correspond to Mendels Laws. _______ disorders are heritable but do not follow Mendelian laws.
Single
Complex/polygenic disorders
106
______ have no current genetic testing available.
Complex/polygenic disorders
107
______ ______ is when more than one gene’s variance can cause the same final phenotype or disease. _____ _____ is when different alleles of the same gene may have multiple distinct phenotypes.
Locus heterogeneity
Allelic heterogeneity
108
A ______ in a pedigree indicates a male. A ____ indicates a female. A ____ is the affected individual by which a family with a genetic disorder is ascertained (first in the family to present to medical attention).
Square
Circle
Proband
109
A ______ degree relative has 50% genes in common like parents, children, and siblings. A _____ degree relative has 25% genes in common like aunts, uncles, nieces, grandparents. A _____ degree relative has 12.5 genes in common like first cousins.
First
Second
Third
