cell cycle

Question 1

how does the cell transition out of metaphase

Answer 1

goes through spindle assembly checkpoint

Question 2

what 2 things are sensed in spindle assembly checkpoint

Answer 2

completion of chromosome alignment, completion of spindle assembly (monitors kinetochore activity as unattached)

Question 3

what 2 things are required for spindle assembly checkpoint

Answer 3

CENP-E, BUB protein kinases

Question 4

what must occur in spindle assembly checkpoint for anaphase to proceed

Answer 4

each BUB protein kinase dissociates from kinetochore when chromosomes are attached to spindle; when all are dissociated, anaphase proceeds

Question 5

2 roads to aneuploidy regarding spindle assembly checkpoint

Answer 5

mis-attachment of microtubules to kinetochores, aberrant centrosome/DNA duplication

Question 6

4 types of attachments of microtubules to kinetochores

Answer 6

syntelic attachment, amphelic attachment, merotelic attachment, monotelic attachment

Question 7

what is syntelic attachment

Answer 7

when the 2 sister kinetochores of an individual chromosome bind microtubules from same spindle pole

Question 8

what is amphitelic attachment

Answer 8

attachment of the 2 sister kinetochores to microtubules from opposite spindle poles (normal attachment)

Question 9

what is merotelic attachment

Answer 9

when a single kinetochore binds microtubules from two poles rather than just one (can break chromosome)

Question 10

what is monotelic attachment

Answer 10

when one of the 2 sister kinetochores of an individual chromosome is attached to one spindle pole whereas the other sister is unattached

Question 11

examples of how syntelic or merotelic attachments cause aneuploid

Answer 11

cohesion defects or syntelic attachments, which cause both sister chromatids to migrate to the same pole, or merotelic attachment, where there is chromosome loss at cytokinesis

Question 12

what does aberrant centrosome/DNA duplication result in

Answer 12

creates 4 centrosomes, misforming and creating multipolar spindles, forming 3 or 4 inviable cells with differing amounts of chromosomes

Question 13

how can anti-cancer therapy induce gross chromosome mis-segregations to kill tumour cells

Answer 13

inhibit attachment-error-correction mechanism, with checkpoint kinase inhibitor binding (cell proceeds to anaphase prematurely), resulting in gross chromosomal mis-segregation and apoptotic cell death

Question 14

what happens during checkpoint kinase (CHKE1 and CHKE2)

Answer 14

serine threonine kinase activation holds cells in G2 phase until all is ready, with inhibition leading to untimely cell transition to mitosis

Question 15

2 examples of breast and ovarian cancer treatments

Answer 15

taxanes and vinca alkaloids

Question 16

what 3 things do taxanes and vinca alkaloids in treating breast and ovarian cancers

Answer 16

alters microtubule dynamics -> produces unattached kinetochores -> causes long-term mitotic arrest

Question 17

3 cell cycle checkpoints, which can be blocked/bypassed by tumours

Answer 17

G2 entering M (checking if DNA damage), metaphase checkpoint (exiting from metaphase; ensures sister chromatid alignment), G1 checkpoint (driven by growth factors)

Question 18

which checkpoint are most tumour progressions present

Answer 18

G1 checkpoint, as increases speed of cycle (growth factors)

Question 19

where do tumorous cells exit the cell cycle, and what do they do

Answer 19

exit cell cycle at G0 (after M) as have no stimulus, but bypass having cell cycle apparatus dismantled so reenter again

Question 20

what happens in G0 (quiescent phase)

Answer 20

cells are not dormant, but are non-dividing (carry out function)

Question 21

how do cells exit from G0 phase

Answer 21

requires growth factors and IC signalling cascades