Mitosis and cancer Flashcards
What is the G0 phase?
State where cell is not going through the cell cycle and dividing
From what point in the cell cycle can a cell enter the G0 phase?
From G1 phase
but before the restriction R point
What can a cell in the G0 phase do?
Can remain in G0
or can re-enter G1 and go through cell cycle and divide
What are the quantities of genetic material in the following phases of the cell cycle?
- G1
- G2
G1 - 46 chromosomes
G2 - 46 replicated chromosomes, 92 sister chromatids
What is the function of the bipolar spindle apparatus?
To ensure that chromosomes are accurately segregated
each daughter cell gets one sister chromatid
What is the bipolar spindle apparatus made up of?
Microtubules
What organises microtubules in a cell?
Centrosomes
How do some cancer treatments target the bipolar spindle apparatus?
Prevent the formation and organisation of microtubules
so bipolar spindle apparatus isn’t formed
How does lack of a bipolar spindle apparatus affect cancer cells?
Lack of cell division
cell death
What is meant by diploid?
Two copies of each chromosome
How are oncogenes affected in cancer cells?
Increased oncogene expression
How are tumour suppressor genes affected in cancer cells?
Decreased tumour suppressor gene expression
What are the types of chromosomal instability?
Structural
Numerical
What can cause numerical chromosomal instability in cancer cells?
Amplified centrosomes
What are amplified centrosomes?
Increased number of centrosomes in dividing cell
more than two
What is a centrosome made up of?
Pair of centrioles
What causes amplified centrosomes?
Uncoupling of centrosome duplication cycle
from cell cycle
How do amplified centrosomes affect the mitotic spindle apparatus?
Give a multipolar spindle apparatus rather than a bipolar one
What are the consequences of a multipolar spindle apparatus?
Chrosomes pulled apart to multiple poles in the cell
daughter cells have severe aneuploidy
die as a result
How do cancer cells with amplified centrosomes survive?
Have developed mechanisms to cluster the extra centrosomes
into two groups
to still form somewhat bipolar spindle apparatus
How can some cancer treatments target clustering of amplified centrosomes?
Inhibit the clustering of amplified centrosomes
so multipolar spindle apparatus forms
cancer cells die
What is the advantage of targeting clustering of amplified centrosomes over targeting the bipolar spindle apparatus?
Targeting the clustering of amplified centrosomes only affects cancer cells
because normal cells have two centrosomes only
whereas targeting the bipolar spindle apparatus affects both cancer cells and normal cells
