2. Cell cycle and its regulation Flashcards
Recall the stages of interphase in eukaryotes
G0 = cell cycle machinary dismantled G1 = decision point S = synthesis G2 = decision point
Recall the structure and function of centrioles
Contain centrioles: referred to as mother and daughter centrioles
Function: Regulate microtubules (are themselves ma)de of microtubules
Summarise the function of prophase
Condensation of chromatin to minimise DNA damage in mitosis; histone wrapping; spindle formation
What is the role of the centromere?
Acts as a “belt” in prophase to constrict chromosomes
What is a kinetochore?
Develops at point of centromere belt: = key regulator of cell cycle processes around chromosomes
How does the kinetochore sense whether it is attached to microtubules?
CENP-E
Summarise the process of spindle formation
- Radial microtubule arrays (asters) form around each centrosome
- Meet between mother and daughter centrosomes: where they meet they are called “polar microtubules”
- Direct chromosome migration
Summarise the process of cytokinesis
- Assembly of contractile ring of actin and myosin which squeezes cell to divide it into 2 daughter cells
- Ring formed at “midbody”
- Cells cleaved at “cleavage furrow”
When is the “spindle assembly” checkpoint?
Between metaphase and anaphase
How does the cell signal passage of the spindle-assemble checkpoint
Whilst kinetochore is unattached, singal proteins are emitted
Once attached, these are no longer produced
Recall the role of BUB protein kinases in cell-cycle progression
Dissociate from the kinetochore when chromatids are attached to spindle to allow progression to anaphase
Give 3 examples of mis-attachment of spindle to kinetochores
Syntelic (both Ks, same centrosome)
Merotelic (more than one microtubule array: one K)
Monotelic (only 1 K is attached)
Where i the spindle-assembly checkpoint can an anti-cancer drug be directed?
Can use inhibitor of spindle-assembly checkpoint so that cell thinks kinetochore is attached and precedes to anaphase when it is not yet ready
Give an example of how a tumour may bypass a cell-cycle checkpoint
May block ability to re-enter G0 after G1, thus forcing cell straight into mitosis