Lecture A4 Flashcards
_____ is necessary to create the ___ different cell types in human body from a single cell zygote
-cell division
-200
5 types of proteins that regulate the cell cycle
I. Growth Factors
II. Growth Factor Receptors
III. Signal Transduction Proteins
IV. Transcription Factors
V. Cell-Cycle Regulators
Phases of the cell cycle
-Go
-G1
-S (DNA replication)
-G2
-M (nuclear division)
-Cytokinesis (cytoplasmic division)
Go phase (def.)
is a form of the resting state, or quiescence, in which cells reside until they receive appropriate signals that tell them to enter cell cycle (G1 extended)
Go cells are ____
quiescent (doing their specialized tasks)
Most of your cells are in this phase: ____
Go
______ control progression through the cell cycle
Cyclin and Cyclin Dependent Kinase (CDK) proteins
Cyclins associated with Go
-Cyclin D
-CDK4
-CDK6
Cyclins associated with G1 (before restriction point in late G1)
-G1 cyclins
-Cyclin D
Cyclins associated with G1 (after restriction point in late G1)
-Cyclin E
-CDK2
Cyclins associated with early S
-S cyclins
-S-phase-promoting factor(SPF) (CDK)
Cyclins associated with S
-Cyclin A
-CDK2
Cyclins associated with end of G2/start of M
-M cyclins
- M-Phase-promoting factor (MPF) -CDK
Cyclins associated with M
-Cyclin B
-CDK1
APC is ____ and does what?
-Anaphase-promoting complex
-a ubiquitin ligase that marks cell cycle proteins for degradation to cause anaphase
end of G1 phase is marked by _____
degradation of G1 cyclins, cyclin E
end of S phase is marked by _____
degradation of S cyclins, cyclin A
end of M phase is marked by _____
degradation of M cyclins, cyclin B
Go cells don’t pass this point?
restriction point
Cyclin D builds when? peaks when?
-G1
-G1
Cyclin E builds when? peaks when?
-G1
-G1/S
Cyclin A builds when? peaks when?
-G1/S
-S
Cyclin B builds when? peaks when?
-S
-M
Go cells partly _____ and exit the cycle to _____ state
-disassemble their cell-cycle control system
-specialized, non-dividing state
Go state and its reversibility is dependent on _____
cell type
cell cycle length depends on _____
time spent in G1/Go
______ are in a terminally differentiated G0 state
Neurons and skeletal muscle cells
terminally differentiated G0 state means that ______
the molecules of the cell-cycle control system are no longer expressed and cell division never occurs
Type of cells in Go but are not terminally differentiated Go+ situation that makes them enter cell cycle
-hepatocytes (stimulated to divide if the liver
is damaged)
-lymphocytes (need)
Maintenance of __________ (4) needs constant cell division so they are most affected by _____
-skin, blood, hair, gut
-chemotherapy
gut stem cells are found where? then they differentiate + migrate to _____
-the bottom of the crypts
-the top and undergo apoptosis
what is scarring?
failure of cell division + cell differentiation
signalling pathways that control cell diversity also impact _____
the cell cycle
Mitogens are ______
subset of cell-extrinsic signalling molecules that can modify the cell cycle
master TF that controls cell cycle
Myc
Myc (def.)
a transcription factor that regulates cell cycle genes like CycD and E2F and itself
SCF (def.)
a factor that regulates degradation of Cyclin proteins
E2F (def.)
a transcription factor that regulates key cell cycle genes and entry into S phase
Myc gene is activated through ____
Ras- Map K pathway
In G1 cells, E2F is activated by _____
the inhibition of Rb (which normally inhibits E2F) by cyclin D1-CDK4 complex
In non-proliferating cells, E2F is _____
inhibited by active Rb
In proliferating cells, E2F is _____
activated by release of inactivated Rb that as been phosphorylated by active cyclin D1-CDK4 complex
_____ acts as an anti-mitogen inducing cells _____
-TGF-β
-to enter G0
Anti-mitogens are also called _____
-anti-growth factors
Commitment (def.)
a change in gene expression has occurred but the effect of the translated proteins has not yet been realized
______ is needed to make neurons from neuronal progenitor cells
Entry into G0 coupled with expression of proneural
transcription factors
