cell cycle Flashcards
How do chromosomes condense?
caused by multiple rounds of folding and coiling - they are condensed by condensin
How do chromosomes attach to the spindle?
microtubules form a network, connecting poles of each cell with each other and the cell wall - microtubules are produced by centrioles
How many centrioles are in a centrosome?
two and centrioles are at 90 degrees from each other
What do astral microtubules do?
bind to the plasma membrane and fix spindle in place
What does the kinetochore microtubule do?
affix to chromosome
What does the interpolar microtubule do?
affix to other microtubules in the spindle
What are the mitotic spindles?
tubulin molecules became polymerised into spirals to form microtubules
What does dynein do in mitosis?
attaches astral microtubules to the plasma membrane
What does kinesin-14 do?
tightens the spindle
What does kinesin-5 do?
expands the spindle
What does kinesin-4, -10 do?
move chromosomes to the poles of the microtubules
What does the centromere do?
joins chromatids together at a single point along their length
What are the layers of the kinetochore?
checkpoint - collar (attaches to spindle), outer - structural, inner - binds to DNA
How are the chromosomes orientated?
so that one chromatid faces each pole of the spindle
What pulls the chromatids apart?
separase
How do spindles shorten?
removal of tubulin from + end, this force pulls kinetochore to pole. removal of tubulin from - end causes depolymerisation of the + end of kinetochore microtubule
What happens during anaphase A?
separation of chromatids and shortening of kinetochore microtubules
What happens during anaphase B?
separation of spindle cores - a sliding force is generated between interpolar microtubules to push the poles apart
What happens during telophase?
spindle degraded, lamin reforma, cytokinesis initiates
What are the phases of the cell cycle?
G1 phases, S phases, G2 phase, M phase
What happens in G2 of interphase?
chromosomes condense, nuclear envelope dissolves, centrosomes replicate
What happens during prophase?
chromosomes fully condense and become visible, spindle forms
What happens during prometaphase?
chromosomes attach to spindle
What happens during metaphase?
chromosomes align at equator