Cell Cycle Control And Cell Division Part II- Exam IV Flashcards
Passage through the start checkpoint in late G1 launches DNA replication and the ______ of the cell cycle
S phase
DNA replication occurs at specific sites:
Origins of replication
The initiated phase of DNA replication is divided into two steps:
- Late mitosis early G1
- Onset of S phase
In the first initiate step of DNA replication in late mitosis-early G1: _____ assembles at the origins of replication
Pre-replication complex
In second step of initiation of DNA replication in the onset of S phase is when the pre-replication complex ______ the formation of the _______.
Nucleates the formation of the pre-initiation complex
The pre-replication complex is formed by various molecules including:
Cdc6 and Cdt1 and then also a helicase
This pre-replication complex occurs in:
G1
The pre-replication complex forms at the
Origins of replciation
After the pre-replication process is formed, its waiting on:
The right signals
THe signal that the phosphorylation complex is waiting on is:
S-cyclin cdk
The s-cyclin CDK is present in the s-phase of the cell cycle because of:
The G1/S CDK activity that proceeds it
The S-cyclin will function to phosphorylate the _____ thereby degrading it:
Cdc6
After the s-cyclin has degraded the cdc6, another set of proteins come in called the:
Pre-initiation complex
The pre-initiation complex functions to:
Launch DNA replication
At the end of DNA replication is when the ____ phase starts:
G2M
The three steps of G1, S, & G2/M:
- Starts with the _____
- Add ___, ___, and _____ to form the pre-replication complex
- The pre-replication complex is converted into a ___ by addition of proteins that bind to the DNA through the action of _____, phosphorylating other proteins present and the DNA is opened up by the action of ____
Once DNA replication is complete, you enter the _____ checkpoint
- Origin of replication
- Cdc6, cdt1, helicase
- Pre-initiation complex; S-CDK, helicase
G2/M
What cell cycle phase does this process occur in:
Formation of the pre-replication complexes at all the replication origins:
G1
What cell cycle phase does this process occur in:
Starts by the formation of the pre-initiation complex’s, and initiation is driven by the S-CDK
S
What cell cycle phase does this process occur in:
DNA replication occurs
S phase
What cell cycle phase does this process occur in:
M-CDK comes along and that triggers chromosome separation and cytokinesis to create the daughter cells
G1
What cell cycle phase does this process occur in:
Assembly of the pre-replication complexes at the origin of replication
G1
If we are talking about the g2/M checkpoint, which phase of the cell cycle is this associated with
Mitosis
The G2M check point is responsible for insuring that:
All the DNA has been properly replicated
What molecules activity abruptly increases at the G2/M checkpoint?
M-CDK
Abrupt increases of the M-CDK activity at the G2/M checkpoint drives:
Entry into mitosis and early mitosis event
Responsible for inducing the assembly of the mitotic spindle, chromosome condensation, promotes breakdown of nuclear envelope, rearrangement of the actin cytoskeleton and Golgi apparatus
M-CDK mediated phosphorylation of specific proteins
Events triggered by M-CDK mediated phosphorylating of specific proteins in conjunction to other families of protein kinases: (4)
- Induces the assembly of mitotic spindle
- Chromosome condensation
- Promotes the breakdown of the nuclear envelope
- Rearrangements of the actin cytoskeleton and Golgi apparatus
How long does it take mitosis from start to finish?
1 hrs
5 phases of mitosis:
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
The interphase events of mitosis encompass:
G1/G0 phase
S phase
G2 phase
What phase is separate from Interphase?
M phase
At prophase the replicated chromosomes consist of:
Two closely associated sister chromatids
What phase of mitosis is this:
Intact nuclear envelope
Centrosomes forming outside the nucleus, beginning to move apart
Forming mitotic spindle
Condensing replicated chromosomes consisting of two chromatids
Prophase
Allows for the chromosomes to attach to spindle microtubules via their kinetic horse:
Breakdown of nuclear envelope
What phase of mitosis is this:
Breakdown of nuclear envelope
Chromosomes attach to spindle microtubules via their kinetichore
Chromosomes in active motion
Prometaphase
Important for the moving apart of chromosomes:
Kinetichores
What phase of mitosis is this:
Chromosomes are aligned at the equator of the spindle
Kinetichore microtubules attach sister chromatids to opposite poles of the spindle
Metaphase
What phase of mitosis is this:
Sister chromatids synchronously separate to form two daughter chromosomes
Kinetichore microtubules shorten
Spindle poles move apart
Anaphase
What phase of mitosis is this:
Set of daughter chromosomes at the spindle pole
Set of daughter chromosomes decondense
new nuclear envelope assembles around each set
Contractile ring starts to form
Telophase
What marks the end of mitosis
Completing the formation of 2 nuclei
During telophase the division of the cytoplasm beings with:
Contraction of contractile rings
Cytoplasm is divided into two by a contractile ring of actin and myosin filaments, which pinches the cell in two to create two daughter cells each with one nucleus:
Cytokinesis
Separation of the two daughter cells is accomplished through
Cytokinesis
Following cytokinesis each daughter cell will have a complete _____ surrounding all of the _____
Nuclear envelope; chromosomes
Following cytokinesis we have:
Two identical daughter cells
When fewer ribosomes are made for example (in the ESCO2 mutation), this will ultimately lead to:
Decrease protein synthesis
Prenatal growth retardation (mild to severe), craniofacial abnormalities such as microcephalic and cleft lip/palate in limb malformations due to a homozygous mutation in ESCO2:
Roberts syndrome
Roberts syndrome is due to a ____ mutation in the gene _____.
Homozygous mutation; ESCO2
ESCO2 is the gene responsible for encoding a _____ important for the formation of the cohesion complex that binds to chormosomes and creates cohesion between sister chromatids:
Acetyl transferase
The acetyl transferase encoded by the ESCO2 is important in the formation of the:
Cohesion complex
The cohesion complex is responsible for binding chromosomes and creating:
Cohesion between sister chromatids
Studies suggest that ESCO2 mutation lead to decreased:
Ribosome production
The metaphase to anaphase transition involves:
Proteolysis
During proteolysis:
1.The APC/C protein binds to _____ producing an active APC/C molecule
2.This process is regulated by:
- The active m-CDK complex ubiquinylates and degrades a protein called _____.
- Securin is normally bound to an and inactive protein called ____.
- When the securin is ubiquinylated and subsequently degrades, the separase becomes ____.
- CDC20
- M-CDK
- Securin
- Separase
- Active
Molecule responsible for breaking down the cohesion complexes that hold the sister chromatids together:
Activated separase
The breakdown of the cohesion complexes by activated separase occurs during:
Anaphase
What are the 3 types of basic signals that control cell division:
- Mitogens
- Growth factors
- Survival factors
Stimulate cell division mainly by stimulating G1/S-CDK activity that inhibits intracellular negative controls that block the progression through the cell-cycle
Mitogens
Stimulate cell growth (increase cell mass) by stimulating protein synthesis and inhibiting protein degradation.
Growth factors
Suppress programmed cell death (apoptosis)
Survival factors
Mitogens act through a highly generalized:
Cascade of MAPK
In the MAPK cascade, the initial stimulase stimulates a:
MAPKKK
The stimulation of the MAPKKK will lead to the stimulation of _____ which leads to the stimulation of ______ and ultimately leading to ______.
Stimulus——> MAPKKK—-> MAPKK—-> MAPK——> Biological response
When Mitogens bind to their cell surface receptor, they will trigger:
Multiple intracellular signaling pathways
One major pathway that the Mitogens trigger is the:
small GTPase Ras signaling proteins
The Ras protein lead to the activation of a ______.
MAP Kinase cascade
When the Ras leads to tacitvation of a MAP Kinase cascade that leads to the activation of:
Multiples early gene expression
Genes that are turned on very early or almost immediately after a Mitogens binds to its receptor:
immediate early gene expression
One of the immediate early gene expressions is a gene called:
Myc
Myc is thought to promote cell cycle entry by:
Increasing the expression of genes encoding the G1 cyclins
Results in increased G1-CDK activity :
Myc increasing the expression of genes encoding G1 cyclins
One of the key functions of G1-CDK is to activate the:
E2F proteins
The E2F proteins are:
Gene regulatory factors
Normally, the E2F proteins are inhibited by an interaction between E2F and the:
Retinoblastoma protein family (Rb)
What is responsible for phosphorylating the Rb protein:
G1-CDK
When the Rb protein gets phosphorylated by G1-CDK, this: (3)
- Renders it inactive
- Reduces its binding to EF2
- Frees EF2
When the EF2 is free it:
activates the expression of target genes
One of the immediate downstream targets of activated E2F is:
S-cyclin
The E2F protein, when activated, leads to:
S-phase of gene transcription
What can directly lead to cell growth:
Growth factor & extracellular factor
What can directly lead to cell division:
Mitogens & extracellular factor
What causes cell growth to go into cell division:
Extracellular factor
Summary of Mitogens induced cell cycle entry and S-phase initiation:
- Mitogens binds to its receptor leading to the activation of _____
- The activation of RAS leads to the activation of _____.
- The activation of MAPK leads to a _____
- The transcription factor binds to _____.
- The immediate early genes lead to the ____
- Myc expression leads to the activation of _____
- Eventually you get DNA synthesis through early inhibition of ____.
- Ras protein
- MAPK
- Transcription factor
- Immediate early genes
- Myc expression
- G1-CDK
- Rb protein
_____ signals through PI3 kinase/AKT signaling
EGF
EGF works through what 3 pathways?
- ERK pathway
- JAK/STAT pathway
- PI3 Kinase/ AKT pathway
EGF pathway that lead to increase protein synthesis:
PI3/AKT pathway
EGF pathway that leads to cell survival and protein synthesis
ERK pathway
The EGF pathway that leads to cell survival
JAK/STAT
Growth factor that has an effect on cell-cycle progression:
TGF beta
When TGF beta binds to the Type I and Type II receptor complex, that leads to:
SMAD pathway
What proteins does the SMAD pathway target?
P15 and P21
The P15 and P21 proteins that are targeted by SMAD resulting in teh inhibitors of:
Cyclin E and Cyclin D
Occurring at the same time of SMAD activating P21 and P15, there is a secondary pathway that leads to the inhibition of:
CDC25
The growth factors are ultimately shutting down the cell cycle process in favor of:
Growth
When growth factors bind to their receptors they lead to:
A series of intracellular events
The signaling events in many instances resulting from growth factors binding their receptors in many instances involve:
PI3 Kinase
The PI3 kinase leads to the intracellular signaling molecule:
PIP3
Downstream, PIP3 leads to the activation of the:
TOR pathway
The TOR pathway eventually leads to:
Protein synthesis and growth
