Cell Cycle Control and Cell Division Part 2

Question 1

G1/S checkpoint (1)

Answer 1

is the environment favorable?

Question 2

pass G1/S checkpoint…

Answer 2

enter cell cycle and proceed to S phase

Question 3

G2M checkpoint (2)

Answer 3

is the DNA replicated?

is the environment favorable?

Question 4

pass G2/M checkpoint…

Answer 4

enter mitosis

Question 5

metaphase to anaphase transition

Answer 5

are all chromosomes attached to the spindle?

Question 6

pass metaphase to anaphase transition…

Answer 6

trigger anaphase and proceed to cytokinesis

Question 7

checkpoint controls (4)

Answer 7

late G1 or start checkpoint
G2/M checkpoint
metaphase to anaphase transition
G0

Question 8

the system is designed to — — through each of the checkpoints if problems are sensed

Answer 8

block progression

Question 9

what is the G0 checkpoint associated with

Answer 9

dREAM complex

Question 10

passage through the start checkpoint in late G1 launches

Answer 10

DNA replication and the S phase of the cell cycle

Question 11

DNA replication occurs at specific sites or

Answer 11

origins of replications (AT rich regions)

Question 12

what two steps is the initiation phase of DNA replication divided into?

Answer 12

late mitosis-early G1: prereplication complex assembles at the origins of replication
onset of S phase when prereplication complex nucleates the formation of the preinitiation complex

Question 13

the G2/M checkpoint ensures that

Answer 13

all of the DNA has been properly replicated

Question 14

abrupt increases in M-cdk activity at the G2/M checkpoint drives (2)

Answer 14

entry into mitosis and the events of early mitosis

Question 15

M-cdk induces (4)

Answer 15

assembly of the mitotic spindle
chromosome condensation
promotes breakdown of the nuclear envelope
rearrangements of the actin cytoskeleton and the goggle apparatus

Question 16

each of the above events is triggered by — mediated — of specific proteins in conjugation with two other families of protein kinases

Answer 16

m-cdk

phosphorylation

Question 17

how long does mitosis take to occur

Answer 17

1 hour

Question 18

phases of mitosis

Answer 18

prophase
prometaphase
metaphase
anaphase
telophase

Question 19

at prophase, the replicated chromosomes, each consisting of two closely associated sister chromatids, —-

Answer 19

condense

Question 20

outside the nucleus the mitotic spindle assembles between the two centrosomes, which are (2)

Answer 20

replicated and moved apart

Question 21

what is at the center of sister chromatids

Answer 21

kinetochore

Question 22

pro metaphase starts abruptly with

Answer 22

the breakdown of the nuclear envelope

Question 23

chromosomes can now

Answer 23

attach to spindle MT via their kinetochores and undergo active movement

Question 24

what allows the chromosomes to line up and move apart?

Answer 24

kinetochore MT

Question 25

chromosome painting

Answer 25

Ab to specific regions of chromosome associated with fluorescent dye
paint the chromosome with dye
can see chromosome rearrangement in metaphase

Question 26

at metaphase, the chromosomes are

Answer 26

aligned at the equator of the spindle, midway between the spindle poles

Question 27

the kinetochore MT attach sister chromatids to

Answer 27

opposite poles of the spindle

Question 28

at anaphase, the sister chromatids

Answer 28

synchronously separate tot form two daughter chromosomes

Question 29

each is pulled slowly toward the

Answer 29

spindle pole it faces

Question 30

what contributes to chromosome segregation? (2)

Answer 30

the kinetochore microtiniles get shorter, and the spindle poles move apart

Question 31

during telophase, the two sets of daughter chromosomes arrive at the poles of the spindle and

Answer 31

decondense

Question 32

a new nuclear envelope reassekhpes around each set, completing the formation of

Answer 32

two nuclei and marking the end of mitosis

Question 33

the division of the cytoplasm begins with

Answer 33

contraction of the contractile ring (cleavage furrow)

Question 34

during cytokinesis. the cytoplasm is divided in to by

Answer 34

a contractile ring of actin and myosin filaments, which pinches the cell into two to create two daughter cells, each with one nucleus

Question 35

Roberts syndrome

Answer 35

Prenatal growth retardation (mild to severe), craniofacial
abnormalities such as microcephaly and cleft lip/palate and
limb malformations (usually limbs are short and the arms
are more severely affected than legs).

Question 36

roberts syndrome is a homozygous mutation of —, which encodes an
— important for the formation of the
cohesion complex that binds to chromosomes and creates
cohesion between sister chromatids.

Answer 36

ESCO2

acetyltransferase

Question 37

Closely related to Cornelia de Lange Syndrome (mutations in

Smc1, Smc3, NIPBL), collectively referred to as

Answer 37

Cohesionopathies

Question 38

Studies suggest that the ESCO2 mutations lead to decreased
— transcription and subsequent — biogenesis
and the observed defects in nucleolar morphology. This
leads to decreased — —

Answer 38

rDNA
ribosomal
protein synthesis

Question 39

extracellular signals controlling cell division (3)

Answer 39

mitogens
growth factors
survival factors

Question 40

mitogens

Answer 40

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

Question 41

growth factors

Answer 41

stimulate cell growth (increase in cell mass) by stimulating protein synthesis and inhibiting protein degradation

Question 42

survival factors

Answer 42

suppress programmed cell death (apoptosis)

Question 43

with growth factors, the cells get bigger but may or may not

Answer 43

divide

Question 44

mitogens interact with cell surface receptors to trigger multiple

Answer 44

intracellular signaling pathways

Question 45

one major pathway involves the small — — signaling proteins

Answer 45

GTPase ras

Question 46

was leads to activation of a

Answer 46

MAP kinase cascade

Question 47

MAP kinase cascade leads to

Answer 47

activation of immediate early gene expression (genes that are tuned on very early or almost immediately after a mitogen binds to its receptor)

Question 48

example of immediate early gene

Answer 48

Myc

Question 49

what does Myc promote

Answer 49

cell cycle entry

Question 50

how does Myc promote cell cycle entry?

Answer 50

by increasing the expression of the genes encoding the G1 cyclins (D cyclins) which results in increased G1-cdk (cyclin D-cdk4) activity

Question 51

One of the key functions of G1-Cdk is to

Answer 51

activate the E2F proteins that are themselves gene regulatory factors

Question 52

Normally the E2F proteins are inhibited by an

interaction between

Answer 52

E2F and the retinoblastoma protein (Rb) family

Question 53

G1-Cdk phosphorylates the — protein, rendering it inactive and reducing its binding to

Answer 53

Rb

E2F

Question 54

phosphorylation of Rb protein …

Answer 54

frees E2F to activate expression of its target genes

Question 55

extracellular factors can lead to (2)

Answer 55

cell growth then cell division

simultaneous cell growth and cell division

Question 56

growth factors lead to

Answer 56

cell growth

Question 57

mitogens lead to

Answer 57

cell division