The Cell Cycle Regulation

Question 1

Two basic parts comprise the cell cycle.

Answer 1

Mitosis and Interphase

Question 2

is the most dramatic stage of
the cell cycle.

Answer 2

Mitosis or Nuclear Division

Question 3

It is the time when the separation of daughter
chromosomes occurs and usually ends with cell division
or cytokinesis.

Answer 3

Mitosis or Nuclear Division

Question 4

A typical eukaryotic cell represented by a
human cell in culture divides approximately
Blank.

Answer 4

every 24 hours.

Question 5

Mitosis and cytokinesis last for approximately an
hour, so about 95% of the cell cycle is spent in
Blank, the period between Blank.

Answer 5

interphase and mitoses.

Question 6

the chromosomes are
decondensed and distributed throughout the
nucleus, so the nucleus appears morphologically
uniform.

Answer 6

interphase

Question 7

at the Blank level, interphase is the
time during which both DNA replication and cell
growth occur as the cell prepares to divide

Answer 7

molecular

Question 8

The cell maintains its growth rate throughout the
?

Answer 8

interphase

Question 9

is synthesized during only a portion of
the interphase.

Answer 9

DNA

Question 10

DNA synthesis divides the cycle of eukaryotic cells into
four discrete phases.

Answer 10

• M phase, G1 phase (gap 1), S phase, and G2 phase (gap 2).

Question 11

The Blank of the cell cycle is the period
when mitosis occurs.
* This is usually followed by cytokinesis.

Answer 11

M phase

Question 12

The mitotic phase is further divided into 4
major phases that include

Answer 12

Prophase, Metaphase, Anaphase, and Telophase.

Question 13

is the one that follows the M
phase, which corresponds to the interval
(gap) between mitosis and initiation of
DNA replication.

Answer 13

G1phase

Question 14

is the synthesis phase following
G1. During this phase, DNA replication
takes place.

Answer 14

S phase

Question 15

follows the completion of DNA
synthesis. During this phase, the proteins
are synthesized in preparation for
mitosis.

Answer 15

G2 phase

Question 16

from the environment regulate the progression
of cells through the division cycle.

Answer 16

Extracellular signals

Question 17

monitor and coordinate the various processes that take place during different cell cycle phases.

Answer 17

Internal signals

Question 18

An example of cell cycle regulation by
extracellular signals is provided by the
effect of Blank on animal cell
proliferation

Answer 18

growth factors

Question 19

TRUE OR FALSE
Also, various cellular processes that occur in cells, such
as growth, DNA replication, and mitosis, must not be
coordinated during the progression of the cell cycle.

Answer 19

False (must be coordinated)

Question 20

What are these regulatory transitions?

Answer 20

1. Start (or the restriction point) in late G1
2. G2/M transition.
3. Metaphase-to-anaphase transition

Question 21

In eukaryotic cells, the Blank generally governs cell-cycle
progression at three major regulatory
transitions

Answer 21

cell-cycle control system

Question 22

• Cell commits to cell-cycle entry
  and chromosome duplication.
• is controlled by external signals
  such as the availability of
  nutrients, as well as by cell size.

Answer 22

Start (or the restriction point) in
late G1.

Question 23

• Control system checks if all DNA has
  been replicated already and if the
  environment is favorable for nuclear
  division and triggers the early mitotic
  events that lead to chromosome
  alignment on the mitotic spindle in
  metaphase.
• Checks if all DNA has been replicated
  already and if the environment is
  favorable to proceed to the next phase
  of the cycle.

Answer 23

G2/M transition.

Question 23

• Control system checks if all
  chromosomes are already
  attached to the spindle and
  stimulate sister-chromatid
  separation, leading to the
  completion of mitosis and
  cytokinesis

Answer 23

Metaphase-to-anaphase
transition

Question 24

If problems are detected inside or outside of the cell, Blank blocks progression through each of the transitions.

Answer 24

the control system

Question 25

Two important checkpoints in eukaryotic cells ensure that complete genomes are transmitted to daughter cells:

Answer 25

1. DNA damage checkpoints 2. spindle assembly checkpoint

Question 26

* Ensure that damaged DNA is not replicated and passed on to daughter cells. * Sense damaged or incompletely replicated DNA and coordinate further cell cycle progression with the completion of DNA replication or repair. * function in G1, S, and G2 and lead to cell cycle arrest in response to damaged or unreplicated DNA.

Answer 26

DNA damage checkpoints

Question 27

Such arrested cells then enter a Blank of the cell cycle called G0, in which they can remain for long periods of time without proliferating. * cells are metabolically active, although they cease growth and have reduced rates of protein synthesis

Answer 27

G0 or quiescent stage

Question 29

* maintains the integrity of the genome occurring towards the end of mitosis. * sees to it that the alignment of chromosomes on the mitotic spindle is successful. * ensure that a complete set of chromosomes is distributed accurately to the daughter cells.

Answer 29

Spindle assembly checkpoint

Question 30

The two key components of the cell cycle control system are the?

Answer 30

cyclin and the cyclin-dependent kinases (Cdks).

Question 30

In the presence of unattached or misattached kinetochores (red circle), the spindle assembly checkpoint is turned on (SAC ON) and the kinetochore proteins Blank, Blank, Blank, Blank assemble at the cytosol to form the Blank. Once the MCC is generated, the CDC20 becomes unable to bind to the Blank, leading to mitotic arrest at the metaphase to anaphase transition.

Answer 30

BUB3, BUBR1, MAD2 and CDC20 mitotic checkpoint complex (MCC) anaphase-promoting complex/cyclosome (APC/C)

Question 31

TRUE OR FALSE Without cyclin, Cdk is active

Answer 31

False (inactive)

Question 32

Cyclins are of four classes

Answer 32

G1/S cyclins S-cyclins M-cyclins G1-cyclins

Question 33

activate Cdks in late G1 and thereby trigger progression through Start, resulting in the commitment to cell-cycle entry. * Their levels fall in the S phase.

Answer 33

G1/S-cyclins

Question 34

are those that bind Cdks soon after progression through Start and help stimulate chromosome duplication.

Answer 34

S-cyclins

Question 35

are those that activate Cdks that stimulate entry into mitosis at the G2/M transition. * Their levels fall in mid-mitosis.

Answer 35

M-cyclins

Question 36

the fourth class of cyclins called the Blank helps govern the activities of the G1/S cyclins, which control progression through Start in late G1.

Answer 36

G1-cyclins