Regulation of Cell Cycle Flashcards
True or False: Rates of cell division will vary depending on cell type
True
True or False: There is rapid turn over of cardiac and neurons but a slow turn over of epithelial cells
False
There is rapid turn over of epithelial cells but slow turn over of cardiac cells and neurons
G1-S-G2 constitutes ___, one of two major process in the cell cycle
Interphase
Mitotic phase consists of: ___ and ___
cytokinesis and mitosis
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 ___
G1; RNA/proteins; duplicate and increase in volume
During S phase, there is transcription and translated mostly for genes related to ____ synthesis and ___
DNA; histones
True or False: During S phase, sister chromatids are converted into chromosomes
False
During S phase, each chromosome is replicated, forming sister chromatids (attached duplicated chromosomes)
True or False: Heterochromatin (histones) increases towards the end of M phase
False
Heterochromatin (histones) increases towards the end of S-phase
During the __ phase of interphase, DNA errors are identified and repaired
G2
___ are cylindrical structures that help organize microtubules
Centrioles
____ are specific regions of chromosomes that allow for attachment of protein complexes known as kinetochores
Centromeres
The centrosome, which is the microtubule organizing center of the cell, is composed of: ___ + ___
centrioles; microtubules
____ is made of tubulin and is known to shorten and lengthen rapidly
microtubules
True or False: During cell division, the centrosome duplicates
True
Attachment of microtubules to ____ will play an important role in separation of sister chromatids during mitosis
kinetochores
____ will form a “mitotic spindle” consisting of microtubules during mitosis
Centrosomes
Stages of mitosis?
1) Prophase
2) Prometaphase
3) Metaphase
4) Anaphase
5) Telophase
During what phase of mitosis does:
-DNA in chromosomes condenses
-kinetochores attach to centromeres
-condensed sister chromatids are formed
Prophase
During what phase of mitosis does:
-nuclear membrane break down
-microtubules bind to kinetochores
Prometaphase
___ are the names of the microtubules that overlap and become bound to one another during metaphase
polar microtubules
During anaphase __ microtubules lengthen, pushing centrosomes to opposite ends of the cell while ___ microtubules shorten, separating sister chromatids
polar; kinetochore
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
Telophase
During cytokinesis, a contractile ring—also known as: cleavage furrow—composed of __ and __ proteins forms between cells
actin; myosin
During ____, the cytoplasm and organelles are separated into two new cells and the membrane of each new cell is sealed off
cytokinesis
What does the Haylink Limit state?
Most human cells can only divide a limited amount of times
Cells in ___ phase have exited the cell cycle but remain functional
G0
True or False: Entry into G0 is always reversible
False
Entry into G0 may be permanent or reversible
True or False: The Hayflick Limit applies to stem cells
False - the Hayflick Limit does NOT apply to stem cells
Stem cell converting into a viable and functional neuron, but no longer able to divide, is an example of ___ ____
terminal differentiation
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.
senescence
In ____ senescence, cells permanently leaves the cell cycle. In other words, this a non-reversible form of senescence.
Replicative senescence
An example of___, a reversible state of G0, is memory of t-cells staying in G0 until stimulated to proliferate
Quiescence
What is a mechanism of replicative senescence?
Telomerase shortening
True or False: stem cells do not express telomerase but somatic cells do
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
What domain of the CDK is activated when cyclin binds?
kinase domain
True or False: Cyclin levels remain constant during the cell cycle while CDK levels rise and fall
False
CDK levels remain constant while cyclin levels rise and fall during cell cycle
Cyclin D combines with CDK _ and CDK _ to allow for progression through G1
CDK4 and CDK6
Cyclin _ and _ combine with CDK2 to initiate DNA synthesis in early S-phase
E, A
Cyclin B combines with CDK1. How does it function?
G2/M transition
CIP/KIP and INK4 are both what type of inhibitors?
cyclin dependent kinase inhibitors (CKI)
INK4 inhibitors block cyclin _ binding, stopping the cell cycle at G1
D
p15, p16, p18, and p19 are all examples of ___
INK4 (cyclin dependent kinase inhibitor)
CIP/KIP inhibitors block CDK _, inhibiting DNA synthesis
p21 is an example a ___/___. What makes p21 special?
CIP/KIP (cyclin dependent kinase inhibitor)
p21 can inhibit multiple CDK complexes, including cyclin: A, B, D, and E
During the ___ checkpoint, the cell checks that kinetochores are bound by microtubules in preparation for cell division
spindle/M checkpoint
The ___ check point will assess DNA damage and induce DNA repair pathways if needed
G2
The early G1 check point is ___ while the late G1 check point is ___
growth factor dependent; growth factor independent
___ 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
Growth ; cyclin D
Typically Rb binds and inhibits ___
E2F (transcription factor)
Activity of E2F up-regulates genes needed for progression of cell cycle, such as ___ _, which moves the cell past the Restriction Point (G1 checkpoint)
Cyclin E
