2.17 Cell Cycle and Apoptosis Flashcards
Confined to a specific part of the body
Local Control
Involves multiple organ systems, or the whole body
Systemic Control
How do cells reproduce
Cell division of existing cells
True or false
DNA replication and cell division must take place in a highly coordinated fashion in eukaryotes
True
True or false
Synthesis takes place after mitosis
False
M after S
Chromosomes are segregated and packaged into separate nuclei
Mitosis
Separation of two nuclei into two genetically identical daughter cells
Cytokinesis
Two major processes of M phase
Mitosis
Cytokinesis
Nucleolus and nuclear envelope are distinct and the chromosomes are in the form of threadlike chromatin
Interphase
Thick, coiled chromosomes, each with two chromatids, are lined up on the metaphase plate
Metaphase
Division into two daughter cells is completed
Cytokinesis
The chromatids of each chromosome have separated and are moving toward the poles
Anaphase
The chromosomes appear condensed, and the nuclear envelope is not apparent
Prophase
The chromosomes are at the poles, and are becoming more diffuse. The nuclear envelope is reforming. The cytoplasm may be dividing
Telophase
Stages of mitosis
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
Bipolar array of microtubules that become attached to the sister chromatids
Mitotic spindle
Mitosis depends on the machinery of the ___
Mitotic spindle
__ movement towards minus end of microtubules, these minus ends are located towards the centrosome
Dynein -mediated
___ movement towards plus end, some microtubule plus ends are attached to the kinetochore
Kinesin-mediated
Large protein complex that provides microtubule binding site on the chromosome
Kinetochore
Movement of the sister chromatids lining up at metaphase plate and connected to the opposite poles
Congression
Holds the sister chromatids together
Cohesin
After birth and before the cell gets ready to split
G1
Exit for non-proliferating, differentiated cells
Cells remain in a quiescent state
G0
Replication
S
Getting ready for mitosis
G2
Mitosis
M
Timing Rapidly dividing human cells Mitosis G1 S G2
around 24 hours; 0.5 h; 9 h 10 h 4.5 h
Timing
Rapidly growing yeast cells
around 90 minutes
E. coli doubing time
20 m
How is the timing maintained?
Dominoes or clocks as model
The next phase is dependent on the previous part
Dominoes
Schedule is followed
Clock
Clock timer that has feedback points for regulation
Control system
Checks for cell size, nutrients, growth factors, and DNA damage
G1/S checkpoint
Restriction point
Checks if replicated DNA is suitable for cell division - no mutation, appropriate cell size
G2/M checkpoint
Check for chromosome attachment to spindle fiber
Metaphase to anaphase checkpoint
Heart of the control system
Cyclins and Cyclin-dependent Kinases (CDK)
True or false
In control system, cyclins are always present while CDKs are variable
False
The other way around
DNA pre-replication complexes are dephosphorylated, and they assemble onto chromosome replication origin
Early G1
G1 CDK compelxes are synthesized
These kinases phosphorylate and activate certain transcription factors
Late G1
Target of the transcription factors are genes encoding components of the ___ , which is blocked by a specific inhibitors
S-phase CDK complex
G1 CDK phosphorylates the inhibitor, targeting it for degradation
Near the start of S-phase
Marks the onset of S-phase
Release of S-phase CDK
Made during S-phase and G2, but activities are inhibited until DNA synthesis is complete
Mitotic CDK complexes
Activation of Mitotic CDK begins at ___
M-phase
Targets cohesin regulators for degradation, allowing segragation of sister chromatids
Anaphase promoting complex (APC)
Degrades mitotic CDK complexes, resulting in the final mitotic events
APC
True or false
Transcription level control is possible after the S phase because DNA is tightly bound as chromosomes
False
Not possible
Kinases turn or or off proteins needed after the S phase through ___
Phosphorylation
Proteins are controlled via:
Phosphorylation
Degradation
Two methods of degradation
Via lysosome
Via ubiquitin-meidated proteasomal degradation
only protein that attaches to cohesin because of the presence of enzymes that are specific to both substrates
Ubiquitin
True or false
Degradation of the stage-specific proteins ensures one way traffic
True
Protein degrading machine
APC
APC is regulated by __
Phosphorylation
Direct anaphase promoter
APC
Protects protein linkages that hold the chromatids, also an inhibitor of separase
Securin
When separase is no longer inhibited by securin, it leads to ___
Cohesin degradation
G1-CDK
Cyclin D
CDK4, 6
G1/S -CDK
Cyclin E
CDK2
S - CDK
Cyclin A
CDK2, 1
M - CDK
Cyclin B
CDK 1
Signal proliferation
Growth factors
Cancer drug which is a proteasome inhibitor
Velcade
Active ingredient in Velcade
Bortezomib
Programmed cell death
Apoptosis
Blebbing of the cell
Apoptosis
Characterized by extensive tissue damage
Cystolic matter spills into the extracellular space through the damaged plasma membrane and this may provoke inflammatory response
Necrosis
Apoptosis is triggered by:
Absence of signals from trophic factors
Internal conditions in the cell (induced by toxins that enter the cell)
External death signals
Failure to pass the cell cycle checkpoints leads to __
Cell cycle arrest
Gene regulator of the cell cycle
Inhibits the activity of cyclin-CDK complexes upon detection of DNA damage
p53
TNF binds to __ (Fas receptor)
Death receptor
Binding of TNF to death receptors which activates caspases and leads to appoptosis
External pathway
Involved after death signaling
Activation of Caspase 8, 3
Fomration of apostosome: mitochondrial cytochrome-c, apaf-1 and caspase 9
Triggers apoptosis
Plasma membrane (GF withdrawal)
Nucleus (irreparable DNA damage)
Death receptor signaling
ER (unfolded proteins)
True or false
Apoptosis is reversible
Depends.
True unless DNA damage is permanent
Implications of reversibility when it comes to chemotherapy
Anastasis
