F lec 18 Flashcards
(127 cards)
1
Q
in _____ of the cell cycle a pre-replication complex (preRC) forms at origins of replication
A
G1
2
Q
at S phase, the _________’s are sites where the 2 kinases DDK and CDK2 phosphorylate substrates to promote DNA replication by DNA polymerase
A
preRC
3
Q
enzyme in S phase that phosphorylates MCM helicase
A
DDK
4
Q
enzyme in S phase that phosphorylates initiator proteins
A
CDK2-cycA
5
Q
CDK2-cyclin A phosphorylates ________________ ______________ at the preRC in S phase
A
initiator proteins
6
Q
DDK phosphorylates ______ ___________________ at the preRC in S phase
A
MCM Helicase
7
Q
in higher eukaryotes, the G1 cyclin is _________ / ____________ and is inhibited by INK4
A
CDK4, cyclin D
8
Q
in higher eukaryotes, the G1/S cyclin is ___________/ _______________, which is inhibited by p27 and p21
A
CDK2, cyclin E
9
Q
in higher eukaryotes, the S cyclin is ___________/ ______________ , which is inhibited by p27 and p21
A
CDK2, cyclin A
10
Q
CDK4- cyclin D is inhibited by ___________
A
INK4
11
Q
CDK2- cyclin E is inhibited by _________ and _________
A
p27, p21
12
Q
CDK2- cyclin A is inhibited by ________ and _________
A
p27, p21
13
Q
after anaphase, APC cdc20 is inactivated and cyclin levels start to ________, which is what leads to _____-_____________
A
rise, S-phase
14
Q
in G1, there is ______ CDK activity
A
low
15
Q
after anaphase, APC ________ is inactivated
A
cdc20 (once mitotic cyclins are degraded to complete anaphase)
16
Q
after anaphase, APC _________ becomes active
A
cdh1
17
Q
APC cdc20 and APC cdh1 are __________________ regulated by phosphorylation (CDK phosphorylation is decreasing due to inactivation of CDKs upon completion of anaphase)
A
oppositely
18
Q
APC cdc20 is only active when ________________
A
phosphorylated
19
Q
APC cdh1 is only active when ___________________
A
dephosphorylated (there is no phosphorylation)
20
Q
APC ___________ is activated in mitosis and then inactivated after it degrades cyclins upon the completion of anaphase
A
cdc20
21
Q
APC __________ is activated when there is low CDK activity - and has the job of maintaining low cyclin levels (keeping them low)
A
cdh1
22
Q
______ is defined as the point in the cell cycle with little to no CDK activity
A
G1
23
Q
in G1 of the cell cycle there are 3 things that keep CDK activity low:
A
cdh1 becomes active, cyclins are at low transcription levels, CDK inhibitors present (mentioned previously INK4, p21, p27 and there are many more undiscussed)
24
Q
cdh1 and CDK inhibitors, along with the low transcriptional levels of cyclins in G1, help keep CDK activity low in G1 which is what allows for ______________ __________________
A
preRC assembly
25
APC cdh1 ________________ _____________ to degrade them
ubiquitinates cyclins (A and B)
26
______ and ______ bind and inhibit CDK2/ cyclin A and CDK2/ cyclin E
p21, p27
27
_____________ binds and inhibits CDK4/ cyclin D
INK4
28
in G1, ________________ transcription is low
cyclin
29
cells that are terminally differentiated (most cells in our body) arrest permanently in a G1-like state referred to as ______
G0
30
in unicellular organisms the main determinant of the rate of cell division is _______________ __________________ for the cell
nutrient availability
31
in multicellular organisms the rate of cell division is largely determined by ____________________ ______________, typically from neighboring cells
extracellular signals
32
in most cells, the decision of when and if to divide is made in _____ of the cell cycle
G1
33
entry into ___-____________ involves sequential activation of G1-CDKs ---> G1/S- CDKs ---> S-CDKs
S-phase
34
cell growth is roughly equated with ___________ ______________
protein synthesis
35
rate of cell division must be coupled to the rate of __________ ______________
cell growth
36
in S. cerevisiae (budding yeast), nutrients entering the cell activate the kinase __________
TOR
37
protein activated by nutrients entering the cell that promotes protein synthesis by promoting ribosome synthesis and ribosome activity, as well as inhibiting 4EBP (discussed earlier in the course)
TOR
38
in _____________ _____________, the growth and protein synthesis generated by the TOR pathway will also signal entry into the S-phase from G1
budding yeast
39
in budding yeast, the G1 cyclin ________ is very unstable (constantly subject to ubiquitin-proteasome degradation)
Cln3
40
in budding yeast, the G1 cyclin Cln3 is very _____________
unstable
41
Cln3 ______________ is inefficient, so accumulation of Cln3 only occurs when translation machinery is highly active
translation
42
Cln3 translation is inefficient, so accumulation of Cln3 only occurs when translation machinery is ____________ _____________
highly active
43
because Cln3 only accumulates when translation is highly active, Cln3 acts as a sensor for ___________ __________ and CDK1-Cln3 activity leads to progression into S-phase
growth rate
44
because Cln3 only accumulates when translation is highly active, Cln3 acts as a sensor for growth rate and ________-_________ activity leads to progression into S-phase
CDK1-Cln3
45
because Cln3 only accumulates when translation is highly active, Cln3 acts as a sensor for growth rate and CDK1-Cln3 activity leads to progression into ____-___________
S-phase
46
under ______ ____________ ______________, yeast cell makes less protein and does not divide
low nutrient conditions
47
under _________ _____________ ________________, TOR is active so there is increased translation and more growth so therefore translation of Cln3 is highly active, so there is higher activity of CDK/Cln3 which triggers entry into S-phase
high nutrient conditions
48
extracellular proteins called ________________ signal the cell to divide
mitogens
49
growth factors and mitogens often bind to the same receptors, which are transmembrane ______________ ______________ _______________
receptor tyrosine kinases
50
extracellular regulators of growth are called ____________ __________________
growth factors
51
extracellular regulators of survival (prevent a cell from performing apoptosis) are called ______________ _______________
survival factors
52
the effect of a given extracellular signal depends on the cell ________________ ____
receiving it
53
many _______________ are also growth factors
mitogens
54
many mitogens such as ____________ and _________ activate the Ras/ MAPK pathway and receptor tyrosine kinase binding causes the receptor to dimerize and trans-phosphorylate - then that receptor can recruit Grb2 (which is an SH2 domain protein recruited to the receptor), then Grb2 binds to Sos (a GEF for Ras) which leads us into a pathway called the Ras/ MAPK pathway
PDGF, EGF
55
many mitogens such as PDGF and EGF activate the Ras/ MAPK pathway and receptor tyrosine kinase binding causes the receptor to ______________ and ______________________ - then that receptor can recruit Grb2 (which is an SH2 domain protein recruited to the receptor), then Grb2 binds to Sos (a GEF for Ras) which leads us into a pathway called the Ras/ MAPK pathway
dimerize, trans-phosphorylate
56
many mitogens such as PDGF and EGF activate the Ras/ MAPK pathway and receptor tyrosine kinase binding causes the receptor to dimerize and trans-phosphorylate - then that receptor can recruit ___________ (which is an _________ _____________ protein recruited to the receptor), then Grb2 binds to Sos (a GEF for Ras) which leads us into a pathway called the Ras/ MAPK pathway
Grb2, SH2 domain
57
many mitogens such as PDGF and EGF activate the Ras/ MAPK pathway and receptor tyrosine kinase binding causes the receptor to dimerize and trans-phosphorylate - then that receptor can recruit Grb2 (which is an SH2 domain protein recruited to the receptor), then Grb2 binds to _________ (a ______ for Ras) which leads us into a pathway called the Ras/ MAPK pathway
Sos, GEF
58
many mitogens such as PDGF and EGF activate the Ras/ MAPK pathway and receptor tyrosine kinase binding causes the receptor to dimerize and trans-phosphorylate - then that receptor can recruit Grb2 (which is an SH2 domain protein recruited to the receptor), then Grb2 binds to Sos (a GEF for ________) which leads us into a pathway called the Ras/ MAPK pathway
Ras (activates Ras)
59
Once Ras becomes bound to GTP after being activated by the GEF Sos, Ras-GTP binds to _______ and activates it, which then phosphorylates MEK to activate it, which then phosphorylates MAPK, allowing MAPK to enter the nucleus
Raf
60
Once Ras becomes bound to GTP after being activated by the GEF Sos, Ras-GTP binds to Raf and activates it, which then ______________________ ________ to activate it, which then phosphorylates MAPK, allowing MAPK to enter the nucleus
phosphorylates MEK
61
Once Ras becomes bound to GTP after being activated by the GEF Sos, Ras-GTP binds to Raf and activates it, which then phosphorylates MEK to activate it, which then ________________ ___________, allowing MAPK to enter the nucleus
phosphorylates MAPK
62
Once Ras becomes bound to GTP after being activated by the GEF Sos, Ras-GTP binds to Raf and activates it, which then phosphorylates MEK to activate it, which then phosphorylates MAPK, allowing MAPK to enter the ________________
nucleus
63
_________ _______________ is the kinase that can phosphorylate transcription factors in the nucleus to activate them
MAP kinase
64
once MAPK enters the nucleus, it phosphorylates and activates ________________ _____________ that promote the expression of 2 genes called myc and fos
transcription factors
65
once MAPK enters the nucleus, it phosphorylates and activates transcription factors that promote the expression of 2 genes called ________ and _________
myc, fos
66
_________ binds to a protein called jun to form the AP1 transcription factor
fos
67
fos binds to a protein called _______ to form the _______ transcription factor
jun, AP1
68
myc and fos promote _______________ ____ ________________
cyclin D transcription
69
_________ represses INK4 transcription and therefore helps activate CDK4 (G1 cyclin)
myc
70
myc ________________ ________ ________________ and therefore helps activate CDK4-cyclin D (G1 cyclin)
represses INK4 transcription
71
the accumulation of cyclin D (due to myc and fos) and the reduction of INK4 (due to myc) leads to the activation of _________-______________
CDK4- cyclin D (first step in the transition from G1 to S)
72
the same RTK that stimulates the Ras/MAPK pathway may also stimulate the ________ pathway
TOR
73
ras, raf, jun, myc were all discovered as _____________ __________________ because they are related to cell division
viral oncogenes
74
once activated by myc and fos, CDK4-cyclin D binds _______, helping to relieve the inhibition of CDK2-cyclin E
p27 (but p27 does not inhibit CDK4 it only inhibits CDK2 so taking it away just frees up CDK2 with no cost to CDK4)
75
after relief of p27 from CDK2 by CDK4, CDK4-cycD and CDK2-cycE phosphorylate ____ to _______________ it, thus activating the protein E2F1
Rb, inactivate
76
after relief of p27 from CDK2 by CDK4, CDK4-cycD and CDK2-cycE phosphorylate Rb to inactivate it, thus activating the protein __________, which drives high level expression of cyclin E and other S-phase genes
E2F1
77
after relief of p27 from CDK2 by CDK4, CDK4-cycD and CDK2-cycE phosphorylate Rb to inactivate it, thus activating the protein E2F1, which drives high level expression of ___________ and other S-phase genes
cyclin E
78
in _____/_____ cyclin E levels are low and all CDK2 cyclin E complexes are inhibited by p27 or p21 binding
G0/G1
79
________________ levels increase in response to mitogens
cyclin D
80
CDK4-cyclin D binds and sequesters ______, allowing for low level activation of CDK2-cyclin E
p27
81
once activated a tiny bit by CDK4 removing p27, CDK2 cycE can now _________________ ______ itself
phosphorylate p27
82
once activated a tiny bit by CDK4 removing p27, CDK2 cycE can now phosphorylate p27 itself - then phosphorylated p27 is recognized by ________ __________________ _____________ and targeted for destruction = POSITIVE FEEDBACK because now CDK2 is activating itself further and further by destroying its own inhibitor
SCF ubiquitin ligase
83
both CDK4 and CDK2 phosphorylate and a protein called Rb, which binds to and inhibits the E2F transcription factor, so indirectly the activity of G1 CDK4 and G1/S CDK2 activates _________, which is then available to go and promote transcription
E2F
84
the ______ gene is famous because it was the first identified tumor suppressor gene
Rb
85
Rb is famous because it was the first identified ______________ _________________ ____________
tumor suppressor gene
86
for now, Rb is named after the type of cancer it causes when it is absent, called ____________________
retinoblastoma
87
Rb is the ________________ of E2F
inhibitor
88
gene that promotes the cell cycle
oncogene
89
gene inhibiting the cell cycle
tumor suppressor gene
90
E2F also has a positive feedback type of activation because once activated by the removal of the Rb inhibitor by CDK4 and CDK2, E2F can serve as its own _______________ ______________ which provides even further activation of E2F and therefore even more transcription of cycE and cycA, cycA being the critical one for transition into S-phase
transcription factor
91
E2F also has a positive feedback type of activation because once activated by the removal of the Rb inhibitor by CDK4 and CDK2, E2F can serve as its own transcription factor which provides even further activation of E2F and therefore even more transcription of cycE and cycA, _________ being the critical one for transition into S-phase
cycA
92
E2F also has a positive feedback type of activation because once activated by the removal of the Rb inhibitor by CDK4 and CDK2, E2F can serve as its own transcription factor which provides even further activation of E2F and therefore even more transcription of _________ and ____________, cycA being the critical one for transition into S-phase
cycE, cycA
93
once activated _________-___ and ___________-____ can both phosphorylate p27 and then trigger its destruction by SCF ubiquitin ligase, further promoting the activation of any CDK2 complexes
CDK2-E, CDK2-A
94
once activated, __________ and ____________ phosphorylate and inactivate APC cdh1 --> and cyclin A is thereby stabilized
CDK2-A, CDK2-E
95
once activated, CDK2-A and CDK2-E phosphorylate and inactivate ________ __________ --> and cyclin A is thereby stabilized - which therefore allows for progression into S phase
APC cdh1
96
once APC cdh1 is inactivated, __________-_______________ promotes S phase by phosphorylating multiple targets
CDK2-cyclin A
97
in higher eukaryotes ______________ pathways are activated by the same thing, those pathways being growth and cell division
parallel
98
in yeast, there is more of a ______________ relationship by which growth in the TOR pathway leads to an increase in levels of a G1 cyclin that leads to buildup and entry into S phase
linear
99
S phase should only occur _____________ in a cycle of cell division
once
100
for DNA replication to occur at S phase, we need pre-replication complexes to form at ____________ ____ ________________ - discrete sites throughout the genome at which complexes assemble in G1 and need to be there to bring replication machinery to that site to initiate DNA replication
origins of replication
101
when deciding which sequence becomes the origin of replication, the decision is based on a DNA sequence that attracts the _________
ORC (origin of replication complex)
102
after binding to a specific DNA sequence, the ORC brings 2 different proteins to the site in ______, which are cdc6 and cdt1
G1
103
after binding to a specific DNA sequence, the ORC brings 2 different proteins to the site in G1, which are _________ and ____________
cdc6, cdt1
104
__________ is first attracted to the ORC, and then it recruits cdt1 along with MCM helicase
cdc6
105
cdc6 is first attracted to the ORC, and then it recruits ___________ along with ________-______________
cdt1, MCM-helicase
106
after MCM-helicase is attracted to the ORC, _________ and ___________ are released
cdc6, cdt1
107
after MCM-helicase is attracted to the ORC, cdc6 and cdt1 are ____________________
released
108
once MCM-helicase is present at the ORC, the preRC is considered to be ___________________ throughout the rest of G1
licensed
109
after licensing of the preRC consisting of MCM-helicase and the ORC, the activity of 2 kinases ( ________ and _________) triggers replication at the origins
CDK2, DDK1
110
kinase at the preRC that phosphorylates initiator proteins
CDK2-cyclin A
111
kinase at the preRC that phosphorylates MCM-helicase
DDK1
112
at the completion of DNA replication, the ________ remain attached to the origin of replication sites - and for the rest of the cell cycle after this replication there is no chance that replication can happen again after one cycle
ORCs (inhibiting another round of replication until a cell division has occurred completely)
113
method of detecting DNA replication using a analogue of dTTP that is incorporated into the cells during S-phase, then fixing the cells and detecting this special substance with primary and fluorescent secondary antibodies - only gets incorporated during S phase
BrdU incorporation (bromodeoxyuridine)
114
preRC assembly is ___________________ after S-phase to ensure that re-replication does not occur
inhibited
115
if the preRC were not present after S-phase, then re-replication would result in ________________ , which is frequently a first step in cancer development
tetraploidy
116
if the preRC were not present after S-phase, then re-replication would result in tetraploidy, which is frequently a first step in _________________ _________________
cancer development
117
type of APC:
APC cdc20
118
type of APC:
APC cdh1
119
pre-replication complexes only form when there is ________ CDK activity
low (therefore forms in G1)
120
in S-phase, CDK2 at peak activity has a role in initiating replication at the preRC, but CDK2 also has other targets, like phosphorylating _________ which leads to its recognition and degradation by SCF ubiquitin ligase
cdc6
121
in S-phase, CDK2 at peak activity has a role in initiating replication at the preRC, but CDK2 also has other targets, like phosphorylating cdc6, which leads to its recognition by ________ ________________ _______________, leading to its degradation = low cdc6 activity
SCF ubiquitin ligase
122
in S-phase other than initiating replication at the preRC and phosphorylating cdc6 to target it for degradation, CDK2 also phosphorylates the _________ which inhibits these preRC from forming
ORC
123
In S-phase, cdt1 is necessary for preRC formation and is inhibited by a protein called ______________ that is present in G2 and mitosis
geminin
124
2 things CDK2 does to prevent the formation of new preRC after S-phase (CDK2 preventing re-replication):
phosphorylates ORC so it cannot recruit preRC, phosphorylates cdc6 to target it for degradation
125
__________________ is a protein that aids CDK2 and the prevention of re-replication after S-phase by inhibiting cdt1 from bringing MCM-helicase to a new preRC
geminin
126
At S phase Cdk2 phosphorylates and activates a number of proteins to promote origin firing.
JUST READ IT
127
At anaphase - APC targets geminin and cyclins for destruction. Low Cdk activity allows Cdc6 accumulation and ORC dephosphorylation and activation.
JUST READ IT - relieves inhibition of preRC formation in G1
