cell cycle
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overview of the cell cycle?
G1 - cell synthesis of proteins S - DNA replication G2 - gap phase M - cell divides
what happens to chromosomes in S and M?
in S, chromosomes are duplicated, in M, chromosomes are segregated into daughter nuclei
what is flow cytometry?
it detects and analyzes chemical and physical characterizations of cells/particles measures fluorescence cells measure amount of DNA (using dye) to tell us cell cycle phase
what are the checkpoints in the cell cycle?
G2 (entering M) - is DNA replicated and is environment favourable metaphase (exiting M) - are all chromosomes attached to spindle G1 (entering S) - is the environment favourable
what happens to cyclin?
forms complex with Cdk (activates it) to trigger specific cell cycle events
what is cdk terminated by?
cyclin degradation
what are the three main cyclins?
G1/S-cyclins activate Cdks at end of G1 and commit cell to DNA replication S-cyclins activate Cdks during S phase for DNA replication M-cyclins promote mitosis sometimes G1-cyclin is included (controls G1 start)
what triggers final part of cell division?
protein destruction
what is APC?
anaphase-promoting complex is activated during metaphase and promotes M-cyclin degradation
what happens do chromosomes at the end of S?
they are a pair of chromatids held together by cohesin
what is the biggest issue in M phase?
segregating its chromosomes
what happens in prophase?
replicated chromosomes condense and mitotic spindle assembles outside nucleus
what happens in prometaphase?
nuclear envelope breaks and microtubules attach to chromosomes at positive ends
what happens in metaphse?
chromosomes align to spindle center Iastral and kinetochore make up the mitotic spindle
what are the main kinesins?
kinesin-5 slides microtubules in opposite directions kinesin-14 crosslinks antiparallel microtubules at center (moves one) kinesin-4/10 are positive direction to push chromosomes to center
what happens in anaphase?
sister chromotids become two chromosomes (spindle also moves)
what are important sensors in anaphase?
aurora B (kinase force sensor) tells cell that chromosomes are orientated properly (if active = improper = low tension) seperase (cysteine protease) triggers anaphase by hydrolysing cohesin
what happens in telophase?
chromosomes arrive at poles, form new nuclear envelopes (end of mitosis and start of cytokinesis)
what does cytokinesis do?
separates two cells using a contractile ring (actin and myosin)
what happens if cytokinesis doesn’t happen?
cells have many nucleus called syncytium
what happens if cytokinesis is incomplete?
cells connected by intercellular bridges
what is endoreplication?
replicates nuclear genome in the absence of mitosis (leads to polyploidy)