Chapter 18 Flashcards
In eukaryotic cells, progression through the cell cycle is controlled by
protein kinases
(nuclear division), usually ending with cell division (cytokinesis).
Mitosis (M phase)
period between mitoses, divided into G1, S, and G2.
Interphase
interval between mitosis and DNA replication. The cell is metabolically active and growing.
G1 phase
DNA replication takes place.
S phase
cell growth continues and proteins are synthesized in preparation for mitosis.
G2 phase
_______ may have cell cycles of 30 minutes, but there is no growth (G1 or G2) phase.
Early embryos
During S phase, replication increases the DNA content to:
4n
______ controls progression from G1 to S, first defined in yeast
START
Passage through START is highly regulated by _______, such as nutrient availability, mating factors and cell size.
external signals
In most animal cells, ________ in late G1 functions like START.
restriction point
If appropriate growth factors are not present in G1, progression stops at the restriction point and cells enter a resting stage called:
Gzero
Coordination of the cell cycle phases is dependent on a series of
cell cycle checkpoints.
ensure that damaged DNA is not replicated and passed on to daughter cells.
DNA damage checkpoints
stops mitosis at metaphase if chromosomes are not properly aligned on the spindle.
Spindle assembly checkpoint
a general regulator of transition from G2 to M.
maturation promoting factor (MPF).
responsible for the progression of the cell cycle (2 things)
cyclins and CDK proteins
Proliferation of animal cells is regulated by extracellular growth factors that control progression through the restriction point in:
late G1.
_____cyclins provide one link between growth factor signaling and cell cycle progression.
D-type
As long as ________ are present through G1, Cdk4,6/cyclin D1 complexes drive cells through the restriction point.
growth factors
Cell cycle arrest at DNA damage checkpoints: (2 things)
ATM and ATR
____ recognizes double-strand breaks; _____ recognizes single-stranded or unreplicated DNA.
ATM, ATR
ATM and ATR phosphorylate and activate the checkpoint kinases, _______.
Chk1 and Chk2
In mammalian cells, arrest at the G1 checkpoint is also mediated by this protein
p53
mitosis phases
Prophase
Metaphase
Anaphase
Telophase
appearance of condensed chromosomes (two sister chromatids).
prophase
The chromatids are attached at the:
centromere
site of eventual spindle attachment
kinetochore
Centrosomes serve as the two poles of:
mitotic spindle
transition between prophase and metaphase.
prometaphase
The chromosomes shuffle back and forth until they align on the ________ plate
metaphase
links between sister chromatids break during this phase
anaphase
nuclei re-form and chromosomes decondense.
telophase
________ usually begins during late anaphase and is almost complete by the end of telophase.
Cytokinesis
Cdk1/cyclin B protein kinase (MPF) is the master regulator of ___ phase transition.
M
These 3 things are activated in a positive feedback loop to signal entry into M phase.
Cdk1, Aurora and Polo-like kinases
contribute to chromosome segregation.
(2 things)
condensins and cohesins
Condensins are activated by Cdk1/cyclin B _________
phosphorylation
The _________ fragments into vesicles at mitosis, which are absorbed into the ER or distributed to daughter cells at cytokinesis.
Golgi apparatus
_________ maturation and spindle assembly involve the Aurora and Polo-like kinases.
Centrosome
_________ turnover rate increases, resulting in depolymerization and shrinkage of the interphase microtubules.
Microtubule
Unattached kinetochores lead to the assembly of the:
mitotic checkpoint complex (MCC)
APC/C ubiquitylates cyclin B and securin, which inactivates Cdk1 and activate:
separase.
Separase degrades ______, which breaks the link between sister chromatids
cohesin
