Cell Cycle Control & Cell Division Part II (Exam IV)

Question 1

Passage through the start checkpoint in late G1 launches DNA replication & the ______ of the cell cycle

Answer 1

S-Phase

Question 2

DNA replication occurs at specific sites:

Answer 2

Origins of replication

Question 3

The initiation phase of DNA replication is divided into two steps:

Answer 3

1- late mitosis-early G1
2- Onset of S phase

Question 4

In the first initiation step of DNA replication in late mitosis-early G1 ______ assembles at the origins of replication

Answer 4

Prereplication complex

Question 5

In the second step of initiation of DNA replication, in the onset of S phase is when the prereplication complex _____ the formation of the _____

Answer 5

Nucleates
Preinitiation complex

Question 6

The prereplication complex is formed by various molecules including:

Answer 6

Cdc6 & Cdt1 & also a helicase

Question 7

The prereplication complex occurs in:

Answer 7

G1

Question 8

The prereplication complex forms at the:

Answer 8

Origins of replication

Question 9

After the prereplication complex is formed, it is just waiting on:

Answer 9

The right signals

Question 10

The signal that the phosphorylation complex is waiting on is:

Answer 10

S-Cyclin-Cdk

Question 11

The S-cyclin-Cdk is present in the S phase of the cell cycle because of:

Answer 11

The G1/S-Cdk activity that precedes it

Question 12

The S-Cyclin will function to phosphorylate the _____ thereby degrading it

Answer 12

Cdc6

Question 13

After the S-cyclin has degraded the Cdc6, another set of proteins come in called the:

Answer 13

Preinitiation complex

Question 14

The Preinitiation complex functions to:

Answer 14

Launch DNA replication

Question 15

At the end of DNA replication is when the ______ phase starts

Answer 15

G2/M

Question 16

The three steps of G1, S & G2/M:

1. Starts with the _______
2. Add _____, _____ & ______ to form the prereplication complex
3. The prereplication complex is converted into a _____ by addition of proteins that bind to the DNA through the action of ______ phosphorylating other proteins present & the DNA is opened in up by the action of _____

Once DNA replication is complete, you enter the ______ checkpoint

Answer 16

1- origin of replication
2- Cdc6, Cdt1, helicase
3- preinitiation complex, S-Cdk, helicase

G2/M

Question 17

What cell cycle phase does this process occur in:

Formation of the prereplicative complexes at all the replication origins

Answer 17

G1

Question 18

What cell cycle phase does this process occur in:

Starts by the formation of the preinitiation complex & initiation driven by the S-Cdk

Answer 18

S

Question 19

What cell cycle phase does this process occur in:

DNA replication occurs

Answer 19

S

Question 20

What cell cycle phase does this process occur in:

M-Cdk comes along & that triggers chromosome separation & cytokinesis to create the daughter cells

Answer 20

M

Question 21

What cell cycle phase does this process occur in:

Driven by the activation of APC/C complex that leads to inactivation of the Cdk

Answer 21

G1

Question 22

What cell cycle phase does this process occur in:

Assembly of the prereplicative complexes at the origins of replication

Answer 22

G1

Question 23

If we are talking about the G2/M checkpoint, which phase of cell-cycle is this associated with:

Answer 23

Mitosis

Question 24

The G2/M checkpoint is responsible for insuring that:

Answer 24

All of the DNA has been properly replicated

Question 25

What molecules activity abruptly increases at the G2/M checkpoint

Answer 25

M-Cdk

Question 26

Abrupt increases of the M-Cdk activity at the G2-M checkpoint drives:

Answer 26

Entry into mitosis & early mitosis events

Question 27

Responsible for inducing the assembly of the mitotic spindle, chromosome condensation, promotes breakdown of nuclear envelope, rearrangement of the actin cytoskeleton & Golgi apparatus:

Answer 27

M-Cdk mediated phosphorylation of specific proteins

Question 28

Events triggered by M-Cdk mediated phosphorylation of specific proteins in conjunction with two other families of protein kinases (4):

Answer 28

1- induces assembly of mitotic spindle
2- chromosome condensation
3- promotes breakdown of nuclear envelope
4- rearrangements of the actin cytoskeleton & Golgi apparatus

Question 29

How long does it take mitosis from start to finish:

Answer 29

1 hour

Question 30

Five phases of mitosis:

Answer 30

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 31

The interphase events of mitosis encompass:

Answer 31

G1/G0 phase
S phase
G2 phase

Question 32

What phase is separate from interphase:

Answer 32

M phase

Question 33

At prophase the replicated chromosomes consist of:

Answer 33

Two closely-associated sister chromatids

Question 34

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 sister chromatids

Answer 34

Prophase

Question 35

Allows for the chromosomes to attach to spindle microtubules via their kinetochores:

Answer 35

Breakdown of nuclear envelope

Question 36

What phase of mitosis is this:

Breakdown of nuclear envelope
Chromosomes attach to spindle microtubules via their kinetochore
Chromosomes in active motion

Answer 36

Prometaphase

Question 37

Important for the moving apart of chromosomes:

Answer 37

Kinetochores

Question 38

What phase of mitosis is this:

Chromosomes are aligned at the equator of the spindle
Kinetochore microtubules attach sister chromatids to opposite poles of the spindle

Answer 38

Metaphase

Question 39

What phase of mitosis is this:

Sister chromatids synchronously separate to form two daughter chromosomes
Kinetochore microtubules shorten
Spindle poles move apart

Answer 39

Anaphase

Question 40

What phase of mitosis is this:

Set of daughter chromosomes at the spindle pole
Set of daughter chromosomes decondense
New nuclear envelope reassembles around each set
Contractile ring starts to form

Answer 40

Telophase

Question 41

What marks the end of mitosis:

Answer 41

Completing the formation of of two nuclei

Question 42

During telophase, the division of the cytoplasm begins with:

Answer 42

Contraction of the contractile ring

Question 43

Cytoplasm is divided in two by a contractile ring of actin & myosin filaments, which pinches the cell in two to create two daughters, each with one nucleus:

Answer 43

Cytokinesis

Question 44

Separation of the two daughter cells is accomplished through:

Answer 44

Cytokinesis

Question 45

Following cytokinesis each daughter cell will have a complete ______ surrounding all of the ____

Answer 45

Nuclear envelope; chromosomes

Question 46

Following cytokinesis we have:

Answer 46

Two identical daughter cells

Question 47

When fewer ribosomes are made (for example in an ESCO2 mutation) this will ultimately lead to:

Answer 47

Decreased protein synthesis

Question 48

Prenatal growth retardation (mild to severe), craniofacial abnormalities such as microcephalic & cleft lip/palate & limb malformations due to a homozygous mutation in ESCO2:

Answer 48

Roberts syndrome

Question 49

Roberts syndrome is due to a ______ mutation in the gene _____

Answer 49

Homozygous mutation; ESCO2

Question 50

ESCO2 is a gene responsible for encoding a _____ important for the formation of the cohesion complex that binds to chromosomes & creates cohesion between sister chromatids

Answer 50

Acetyltransferase

Question 51

The Acetyltransferase encoded by ESCO2 is important in the formation of the:

Answer 51

Cohesion complex

Question 52

The cohesion complex is responsible for binding chromosomes & creating:

Answer 52

Cohesion between sister chromatids

Question 53

Studies suggest that the ESCO2 mutation lead to decreased:

Answer 53

Ribosome production

Question 54

The metaphase to anaphase transition involves:

Answer 54

Proteolysis

Question 55

During proteolysis:

The APC/C protein binds to ____ to produce an active APC/C molecule

This process is regulated by:

The active M-Cdk complex ubiquitylates & degrades a protein called:

Securin is normally bound to an inactive protein called:

When securin is ubiquinated & subsequently degrades the separase becomes _____

Answer 55

Cdc20
M-Cdk
Securin
Separase
Active

Question 56

Molecule responsible for breaking down the cohesion complexes that hold the sister chromatids together:

Answer 56

Activated separase

Question 57

The breakdown of the cohesion complexes by activated separase occurs during:

Answer 57

Anaphase

Question 58

Three types of basic signals that control cell division:

Answer 58

Mitogens, growth factors, survival factors

Question 59

Stimulate cell division mainly by stimulating G1/S-Cdk activity that inhibits intracellular negative controls that block the progression through the cell-cycle

Answer 59

Mitogens

Question 60

Stimulate cell growth (increase cell mass) by stimulating protein synthesis & inhibiting protein degradation:

Answer 60

Growth factors

Question 61

Suppress programmed cell death (apoptosis)

Answer 61

Survival factors

Question 62

Mitogens generally act through a highly generalized:

Answer 62

Cascade of mitogen-activated protein kinases (MAPK)

Question 63

In the MAPK cascade:

The initiate stimulus stimulates a ______

Answer 63

MAPKKK

Question 64

In the MAPK cascade:

The stimulation of the MAPKKK will lead to the simulation of _____ which leads to the stimulation of _______ & ultimately leading to ____

Answer 64

Stimulus —> MAPKKK —> MAPKK —> MAPK —> biological response

Question 65

When mitogens bind to their cell surface receptor they will trigger:

Answer 65

Multiple intracellular signaling pathways

Question 66

A major pathway that the mitogen trigger is the:

Answer 66

Small GTPase Ras signaling proteins

Question 67

The Ras protein leads to the activation of a:

Answer 67

MAP-Kinase cascade

Question 68

When the Ras leads to the activation of a MAP-kinase cascade that leads to the activation of:

Answer 68

Multiple early gene expression

Question 69

Genes that are turned on very early or almost immediately after a mitogen binds to its receptor

Answer 69

Immediate early gene expression

Question 70

One of the immediate early gene expressions is in a gene called:

Answer 70

Myc

Question 71

Myc is thought to promote cell cycle entry by:

Answer 71

Increasing the expression of genes encoding the G1 cyclins

Question 72

Results in increased G1-Cdk activity:

Answer 72

Myc increasing the expression of genes encoding G1 cyclins

Question 73

One of the key functions of G1-Cdk is to activate the:

Answer 73

E2F proteins

Question 74

The E2F proteins are:

Answer 74

Gene regulatory factors

Question 75

Normally the E2F proteins are inhibited by an interaction between E2F & the:

Answer 75

Retinoblastoma protein family (Rb)

Question 76

What is responsible for phosphorylating the Rb protein:

Answer 76

G1-Cdk

Question 77

When the Rb protein is phosphorylated y G1-Cdk, this (3):

Answer 77

1- renders it inactive
2- reduces it binding to EF2
3- Frees EF2 to activate expression of its target genes

Question 78

When the EF2 is free it:

Answer 78

Activates the expression of target genes

Question 79

One of the immediate downstream targets of activated E2F is:

Answer 79

S-cyclin

Question 80

When activated the E2F proteins leads to:

Answer 80

S-phase of gene transcription

Question 81

Can directly lead to cell growth:

Answer 81

Growth factor & extracellular factor

Question 82

Can directly lead to to cell division:

Answer 82

Mitogens & extracellular factor

Question 83

Causes cell growth to go into cell division:

Answer 83

Extracellular factor

Question 84

Summary of mitogen induced cell-cycle entry & S-phase initiation:

1- mitogen binds to its receptor leading to the activation of ____
2- the activation of RAS leads to the activation of ____
3- the activation of MAPK leads to a _____
4- the transcription factor binds to ______
5- the immediate early genes leads to _______
6- myc expression leads to the activation of _____
7- eventually you get DNA synthesis through early inhibition of ____

Answer 84

1- RAS
2- MAPK
3- transcription factor
4- immediate early genes
5- Myc expression
6- G1-Cdk
7- Rb protein

Question 85

Signals through PI3 kinase/AKT signaling

Answer 85

EGF

Question 86

EGF works through what three pathways:

Answer 86

1- ERK
2- JAK/STAT
3- PI3 Kinase/AKT

Question 87

EGF pathway that leads to increased protein synthesis:

Answer 87

PI3/AKT

Question 88

EGF pathway that leads to cell survival & protein synthesis:

Answer 88

ERK

Question 89

EGF pathway that leads to cell survival:

Answer 89

JAK/STAT

Question 90

Growth factor that has an affect on cell cycle progression

Answer 90

TGF-Beta

Question 91

When TGF-beta binds to the type I & type II receptor complex, that leads to the:

Answer 91

SMAD pathway

Question 92

Proteins targeted by the SMAD pathway

Answer 92

P15
P21

Question 93

P15 & P21 proteins (that are targeted by SMAD) result in the inhibition of:

Answer 93

Cyclin E
Cyclin D

Question 94

Occuring at the same time of SMAD activating P21 & P15, there is a second pathway that leads to the inhibition of:

Answer 94

Cdc25

Question 95

Growth factors are ultimately shutting down the cell cycle process in favor of:

Answer 95

Growth

Question 96

When growth factors bind to their receptors this leads to:

Answer 96

A series of intracellular events

Question 97

The signaling events resulting from growth factors binding to their receptors in many instances involve the:

Answer 97

PI3 kinase

Question 98

The PI3 kinase leads to the intracellular signaling molecule:

Answer 98

PIP3

Question 99

Downstream, PIP3 leads to the activation of the:

Answer 99

TOR pathway

Question 100

The TOR pathway eventually leads to:

Answer 100

Protein synthesis & growth