Lecture 23: Cell Cycle

Question 1

Each living cells undergoes growth and cell division resulting in the formation of ___________________ each of which contains the same genetic information

Answer 1

Two daughter cells

Question 2

The cell cycle is a balance of _____________ and ______________

Answer 2

cell division and cell death

Question 3

What are the stage of the cell cycle, which are the __________________, _____________, ______________ and _____________

Answer 3

G1, S, G2, and M phase

Question 4

What occurs during interphase

Answer 4

G1, S, and G2

it is the longest phase

Question 5

___________________ lasts for hours to several days, cell grows and proteins are synthesized, restoring daughter cells to normal volume and size, cells preparing for S phase

Answer 5

G1 phase

Question 6

_________ no cell division occurs

Answer 6

G0

Question 7

_________ RNA and protein synthesis, cell growth

Answer 7

G1 phase

Question 8

_____________- DNA replication, Histone synthesis, centrosome formed, chromosome duplication

Answer 8

S phase

Question 9

_________ preparation for mitosis

Answer 9

G2 phase

Question 10

______ mitosis, prophase, metaphase, anaphase, telophase, cytokinesis. Chromosome seperation, cell division

Answer 10

cytokinesis

Question 11

____________ also known as quiescence, temporarily suspend in non dividing rest cells, cells are in a stable state, cellular processes in the cell are continuing as usual, cells may reenter the cycle to begin to divide again through growth factors or can be made to enter through other means

Answer 11

Go Phase (Gap outside phase)

Question 12

_____________ DNA replication occurs, histone and non histone protein synthesis occurs, duplication of chromosomes, at the end of the S phase, chromosome consist of two double strands, cohesion applied to hold sister chromatids tightly together

Answer 12

S phase

Question 13

_____________________ several proteins regulated the cohesion complex interaction and chromatin. The roles of cohesion:
1. regulates sister chromatic cohesion during meiosis and mitosis
2. Regulates DNA replication
3. Regulates DNA repair
4. Regulates transcription

Answer 13

Cohesion complex

Question 14

________________ abnormalities in these genes are associated with multi system developmental disorders which are termed

Answer 14

Cohesionpathies

Question 15

____________ lasts 2-4 hours, extends to M phase, cells prepare for mitosis, second growth phase, high rate of cellular activity, energy required for the complete of mitosis is accumulated. RNA proteins and tubules for spindle apparatus are synthesized

Answer 15

G2 phase

Question 16

___________________ chromosomes begin to condense
Centrosomes made of two centrioles at tight angles, move to oppose pose of cell beginning formation of the spinal apparatus, nuclear membrane begins to break down

Answer 16

Prophase

Question 16

______________ nuclear membrane completely broken down, chromosomes continue to condense, centromere attach to spindle fibers and chromosomes move toward midway point between spindle poles

Answer 16

Prometaphase

Question 17

________________. chromosomes become fully condensed by end of this phase, chromosomes align on fibers of spindle apparatus at midway point, specialized proteins called kinetochores bind to centromeres and attach to chromosomes to spindle fibers

Answer 17

metaphase

Question 18

_______________ sister chromatids separate and move to opposite poles of spindle apparatus

Answer 18

Anaphase

Question 19

______________ chromosome begin to decondense, two nuclear membranes to form

Answer 19

Telophase

Question 20

____________ formation of two new daughter cells by division of cytoplasmic contents

Answer 20

Cytokinesis

Question 21

__________________ both sister chromatids go to same pole, it produces both trisomic and monosomic cells aneuploidy

Answer 21

Non disjunction

Question 22

__________________
separated sister chromatid “lags” behind and is not included within new nuclear membrane, micronucleus with lone chromosomes forms in cytoplasm, eventually lost from cell, results in monosomic cells,

Answer 22

anaphase lag

Question 23

________________is a ubiquitin ligase that
controls the levels of the M-phase
cyclins as well as other regulators of
mitosis. One important function of
APC is to control the initiation of
sister chromatid separation which
begins at the metaphase-anaphase
transition. The attachment of the
sister chromatids to the opposite
poles of the mitotic spindles occurs
early during mitosis. The ability of
the sister chromatids to be pulled
apart is initially inhibited because
they are bound together by a protein
complex termed cohesin complex.

Answer 23

The anaphase-promoting complex
(APC)

Question 24

____________________
*Initiate/induce cell progression through the
cell cycle
*Progression can be STOPED by various
checkpoints
* Accuracy of cellular events is monitored.
_____________________ key player
for cell cycle regulation
____________________for their
activity

Answer 24

Cyclins and Cyline dependent kinases
*Cyclin-dependent kinsase (Cdk)

Question 25

What are some checkpoints in G1 phase

Answer 25

*Cyclins D & E bind to their
respective Cdk’s
*Cyclin D: helps the passage
of cells through restriction
point in late G1 phase.
*Cyclin E: helps the cells at
the end of G1 phase to
commit to DNA replication
and enter S phase.
*Enable cell to enter/advance
to S phase

Question 26

What are some checkpoints are in the G1 and S phase

Answer 26

*Replication of DNA is monitored
*If errors are detected, the cell
cycle cannot continue until errors
corrected
*G1 DNA damage checkpoint
*S DNA damage checkpoint

Question 27

What are some checkpoints in the S phase

Answer 27

*Cyclin A binds to its CDK
*Cyclin A: enables cell to
leave S phase and enter G2
phase
Necessary for the initiation
of DNA synthesis
*Cyclin B is manufactured.

Question 28

What are some checkpoints at the G2 phase

Answer 28

*Replication of DNA is monitored
*If errors are detected, the cell cycle
cannot continue until errors corrected
*Unreplicated DNA checkpoint:
DNA that hasn’t been replicated can
not pass. Making sure S phase
occurred.
*G2 DNA damage checkpoint:
prevents the continuation of the G2
phase if errors are present in the
replicated DNA
*Cyclin B binds to its CDK
*Cyclin B: induces the cell
to leave the G2 phase and
enter the M phase
*Cyclin B is manufactured.

Question 29

Checkpoints at the M phase

Answer 29

Spindle Assembly Checkpoint:
*When: Beginning of the M phase
*Monitored: Spindle apparatus
If Spindle apparatus is faulty cell cannot leave
the M phase.
Chromosome Segregation Checkpoint
*When: End of the M phase
*Monitored: condition of chromosomes
if any of the chromosomes are sticking to each
other, cell is not permitted to leave M phase

Question 30

Tumor suppressor _______________ normally halts
cells in the G1 phase of the cell cycle.
In normal, resting cells, the RB
protein is unphosphorylated
RB prevents a cell’s entry into S
phase by binding to transcription
factor E2F and its binding partner
DP1/2, which are critical for the
G1/S transition
RB normally prevents progression
out of early G1 and into S phase in a
resting cell.

Answer 30

RB

Question 31

*The retinoblastoma protein (pRb or RB or
RB1)
*tumor suppressor
*important role in regulating the progression of
proliferating cells through the cell cycle
*the exit of differentiating cells from the cell
cycle.
* This protein affects these two functions by
sequestration of other transcription factors
and by promoting deacetylation of histones,
a chromatin modification associated with
gene silencing.
*Pathogenic variants cause ______________

Answer 31

Retinoblastoma

Question 32

Activation of mitotic ____________involves the addition of inhibiting and
activating phosphate groups
* Followed by removal of the inhibiting phosphate groups by a phosphatase.
* Once removal of the inhibiting phosphate groups has begun, a positive
feedback loop is set up:
* The activated Cdk-cyclin complex generated by this reaction stimulates the
phosphatase, thereby causing the activation process to proceed more
rapidly

Answer 32

Cdk-cyclin

Question 33

What two produces produce a response to damage to DNA

Answer 33

-ATM
-ATR

Question 34

ATM and ATR leads to the activation of p53 which in turn stimulates transcription of p21, which binds Cdks in G1 and S preventing progression of the cell cycle until ______________

Answer 34

damage DNA is repaired

Question 35

If DNA is too damaged p53 _________________

Answer 35

initiates apoptosis

Question 36

transcription factor p53
responds to diverse cellular
stresses to regulate target genes
that induce cell cycle arrest,
apoptosis, senescence, DNA
repair, or changes in metabolism
*p53 appears to induce apoptosis
through nontranscriptional
cytoplasmic processes
*Pathogenic variants cause ________________

Answer 36

Li Fraumeni syndrome