Regulation of Cell Cycle

Question 1

True or False: Rates of cell division will vary depending on cell type

Answer 1

True

Question 2

True or False: There is rapid turn over of cardiac and neurons but a slow turn over of epithelial cells

Answer 2

False
There is rapid turn over of epithelial cells but slow turn over of cardiac cells and neurons

Question 3

G1-S-G2 constitutes ___, one of two major process in the cell cycle

Answer 3

Interphase

Question 4

Mitotic phase consists of: ___ and ___

Answer 4

cytokinesis and mitosis

Question 5

During __ phase of interphase, there is high levels of ___ and synthesis of ____. Further the cell grows and organelles (lysosome and mitochondria) begin to ___ and increase in ___

Answer 5

G1; RNA/proteins; duplicate and increase in volume

Question 6

During S phase, there is transcription and translated mostly for genes related to ____ synthesis and ___

Answer 6

DNA; histones

Question 7

True or False: During S phase, sister chromatids are converted into chromosomes

Answer 7

False

During S phase, each chromosome is replicated, forming sister chromatids (attached duplicated chromosomes)

Question 8

True or False: Heterochromatin (histones) increases towards the end of M phase

Answer 8

False
Heterochromatin (histones) increases towards the end of S-phase

Question 9

During the __ phase of interphase, DNA errors are identified and repaired

Answer 9

G2

Question 10

___ are cylindrical structures that help organize microtubules

Answer 10

Centrioles

Question 11

____ are specific regions of chromosomes that allow for attachment of protein complexes known as kinetochores

Answer 11

Centromeres

Question 12

The centrosome, which is the microtubule organizing center of the cell, is composed of: ___ + ___

Answer 12

centrioles; microtubules

Question 13

____ is made of tubulin and is known to shorten and lengthen rapidly

Answer 13

microtubules

Question 14

True or False: During cell division, the centrosome duplicates

Answer 14

True

Question 15

Attachment of microtubules to ____ will play an important role in separation of sister chromatids during mitosis

Answer 15

kinetochores

Question 16

____ will form a “mitotic spindle” consisting of microtubules during mitosis

Answer 16

Centrosomes

Question 17

Stages of mitosis?

Answer 17

1) Prophase
2) Prometaphase
3) Metaphase
4) Anaphase
5) Telophase

Question 18

During what phase of mitosis does:
-DNA in chromosomes condenses
-kinetochores attach to centromeres
-condensed sister chromatids are formed

Answer 18

Prophase

Question 19

During what phase of mitosis does:
-nuclear membrane break down
-microtubules bind to kinetochores

Answer 19

Prometaphase

Question 20

___ are the names of the microtubules that overlap and become bound to one another during metaphase

Answer 20

polar microtubules

Question 21

During anaphase __ microtubules lengthen, pushing centrosomes to opposite ends of the cell while ___ microtubules shorten, separating sister chromatids

Answer 21

polar; kinetochore

Question 22

During ___ phase of mitosis, the kinetochores and mitotic spindles disassemble, nuclear membrane reforms, and chromosomes de-condense. Further: chromosomes are equally separated to opposite poles of the cell

Answer 22

Telophase

Question 23

During cytokinesis, a contractile ring—also known as: cleavage furrow—composed of __ and __ proteins forms between cells

Answer 23

actin; myosin

Question 24

During ____, the cytoplasm and organelles are separated into two new cells and the membrane of each new cell is sealed off

Answer 24

cytokinesis

Question 25

What does the Haylink Limit state?

Answer 25

Most human cells can only divide a limited amount of times

Question 26

Cells in ___ phase have exited the cell cycle but remain functional

Answer 26

G0

Question 27

True or False: Entry into G0 is always reversible

Answer 27

False
Entry into G0 may be permanent or reversible

Question 28

True or False: The Hayflick Limit applies to stem cells

Answer 28

False - the Hayflick Limit does NOT apply to stem cells

Question 29

Stem cell converting into a viable and functional neuron, but no longer able to divide, is an example of ___ ____

Answer 29

terminal differentiation

Question 30

In response to stress, toxins, lack of nutrients, or damage, a cell can enter G0 where they are viable yet non-dividing. This process, known as ____, involves genetic and metabolic reprogramming.

Answer 30

senescence

Question 31

In ____ senescence, cells permanently leaves the cell cycle. In other words, this a non-reversible form of senescence.

Answer 31

Replicative senescence

Question 32

An example of___, a reversible state of G0, is memory of t-cells staying in G0 until stimulated to proliferate

Answer 32

Quiescence

Question 33

What is a mechanism of replicative senescence?

Answer 33

Telomerase shortening

Question 34

True or False: stem cells do not express telomerase but somatic cells do

Answer 34

False
Stem cells express telomerase but somatic cells do not. Therefore, the prior cells can replicate infinitely, maintaining telomere length, while the latter eventually undergo senescence due to telomere shortening

Question 35

What domain of the CDK is activated when cyclin binds?

Answer 35

kinase domain

Question 36

True or False: Cyclin levels remain constant during the cell cycle while CDK levels rise and fall

Answer 36

False
CDK levels remain constant while cyclin levels rise and fall during cell cycle

Question 37

Cyclin D combines with CDK _ and CDK _ to allow for progression through G1

Answer 37

CDK4 and CDK6

Question 38

Cyclin _ and _ combine with CDK2 to initiate DNA synthesis in early S-phase

Answer 38

E, A

Question 39

Cyclin B combines with CDK1. How does it function?

Answer 39

G2/M transition

Question 40

CIP/KIP and INK4 are both what type of inhibitors?

Answer 40

cyclin dependent kinase inhibitors (CKI)

Question 41

INK4 inhibitors block cyclin _ binding, stopping the cell cycle at G1

Answer 41

D

Question 42

p15, p16, p18, and p19 are all examples of ___

Answer 42

INK4 (cyclin dependent kinase inhibitor)

Question 43

CIP/KIP inhibitors block CDK _, inhibiting DNA synthesis

Question 44

p21 is an example a ___/___. What makes p21 special?

Answer 44

CIP/KIP (cyclin dependent kinase inhibitor)

p21 can inhibit multiple CDK complexes, including cyclin: A, B, D, and E

Question 45

During the ___ checkpoint, the cell checks that kinetochores are bound by microtubules in preparation for cell division

Answer 45

spindle/M checkpoint

Question 46

The ___ check point will assess DNA damage and induce DNA repair pathways if needed

Answer 46

G2

Question 47

The early G1 check point is ___ while the late G1 check point is ___

Answer 47

growth factor dependent; growth factor independent

Question 48

___ factors bind cellular receptors and initiate the cell cycle in early G1. As a result of these factors, there is an increase in ___ _ levels, which activated CDK4/6. Activated CDK4/6 phosphorylates Rb, which changes the structure of Rb, causing it to release E2F

Answer 48

Growth ; cyclin D

Question 49

Typically Rb binds and inhibits ___

Answer 49

E2F (transcription factor)

Question 50

Activity of E2F up-regulates genes needed for progression of cell cycle, such as ___ _, which moves the cell past the Restriction Point (G1 checkpoint)

Answer 50

Cyclin E