cells can be fused in vitro by adding:
ethylene glycol
diffusable factor in M-phase cells can induce G1 phase cell to enter M-phase
MPF
diffusible factor responsible for initiating S-phase
SPF
diffusable S-phase factor (SPF) does not act on:
G2 phase
xenopus females lay eggs when injected with:
hCG
oocytes are arrested this in cell phase
G2
meiosis induced in oocyte arrested in G2 by:
steroid hormone (progesterone)
egg arrested in this phase after progesterone previously added
Meiosis II
egg arrests in metaphase of Meiosis II until:
fertilization
fertilization induces completion of: (3)
meiosis, pronuclear fusion, mitotic cleavage
orientation of kinetochores during Mesiosis I
co-orientation
2 phases not part of Meiosis II
interphase and prophase
during oogenesis, this is discarded and becomes 1st polar body
2n daughter cell
during oogenesis, this is discarded and becomes 2nd polar body
1n
chromosome recombination happens in:
meiosis I
cytoplasm from oocytes arrested in this phase induces oocytes arrested in G2 to enter meiosis
meiosis II
promotes entry into the cell cycle
Maturation Promoting Factor (MPF)
test MPF level of cell phase by:
removing cytoplasm (at different stages) and inject into G2 oocyte (arrested)
hormone induces MPF activity
progesterone
MPF levels high during these parts of cell cycle
Meiosis I, Meiosis II metaphase arrest, 1st embryonic mitosis, 2nd embryonic mitosis
chemical blocks: (2)
MPF activity and translation
MPF activity is independent of: (2)
nucleus and transcription
location components required for cell cycle progression stored
cytoplasm
levels of this protein crash right before cleavage
Cyclin B
activity of this rises/falls in synchrony with cyclin B concentration
MPF
rise of MPF is necessary to:
enter mitosis
fall of MPF activity and exit from mitosis depend on:
degredation of Cyclin B
organism type does not divide evenly
budding yeast
way to assay mutants in genes controlling cell cycle (which typically cannot be recovered)
conditional loss-of-function mutation
mutant prevents entry into mitosis
cdc2
cdc2 mutant is characterized by:
larger than normal cells
type of cdc2 mutation produces very small cells
dominant cdc2
mutant arrests in G1 phase wihtout entering S-phase
cdc28 mutant
cdc28 is a condidate for:
SPF
cdc2 acts in these transitions
G2 to M and G1 to S
cdc2 cell cycle transition more sensitive to changes in MPF
C2 to M
cdc28 acts in these transitions
G2 to M and G1 to S
cdc28 cell cycle more sensitive to changes in SPF
G1 to S
technique used to assay yeast genomic library
functional complementation
cdc2 and cdc28 encode small proteins with kinase activity
Cyclin Dependent Kinases (CDK)
CDK protein regulated by:
cyclin
part of cyclin blocks access of protein substrates to g-phosphate of ATP in free CDK
T-loop
this induces conformational change that pulls T-loop of cyclin from actin site
Cyclin A binding
point in late G1 phase when cell becomes irrevocably commited to entering cell cycle
START
inactive cdc28 mutants after START arrest in:
G1
cdc mutants cannot pass:
START
CLN1, CLN2, and CLN3 drive this cell cycle transition
G1 to S
overexpression of CLN1, CLN2, or CLN3 decreases:
number of cells in G1 (cells go through G1 quicker)
technique sorts cells based on DNA content
flow cytometry
flow cytometry: amount of fluorescence proportional to:
amount of DNA in cell
two general sypes of cyclins in vertebrates
G1 type and B-type cyclins
cyclin acts in G1
G1 cyclin
B-type cyclins act in these parts of cell cycle
S, G2, and M
G1 type cyclins act in Mid-G1
CLN3 and Cyclin D
G1 type cyclins act in late G1
CLN1, CLN2, and Cyclin E
general types of cyclins contain conserved destruction box for degradation by APC/C
B-type cyclins
specific types of B-type cyclins
Cyclin A and Cyclin B