Mitosis and cancer

Question 1

What is the G0 phase?

Answer 1

State where cell is not going through the cell cycle and dividing

Question 2

From what point in the cell cycle can a cell enter the G0 phase?

Answer 2

From G1 phase

but before the restriction R point

Question 3

What can a cell in the G0 phase do?

Answer 3

Can remain in G0

or can re-enter G1 and go through cell cycle and divide

Question 4

What are the quantities of genetic material in the following phases of the cell cycle?

• G1
• G2

Answer 4

G1 - 46 chromosomes

G2 - 46 replicated chromosomes, 92 sister chromatids

Question 5

What is the function of the bipolar spindle apparatus?

Answer 5

To ensure that chromosomes are accurately segregated

each daughter cell gets one sister chromatid

Question 6

What is the bipolar spindle apparatus made up of?

Answer 6

Microtubules

Question 7

What organises microtubules in a cell?

Answer 7

Centrosomes

Question 8

How do some cancer treatments target the bipolar spindle apparatus?

Answer 8

Prevent the formation and organisation of microtubules

so bipolar spindle apparatus isn’t formed

Question 9

How does lack of a bipolar spindle apparatus affect cancer cells?

Answer 9

Lack of cell division

cell death

Question 10

What is meant by diploid?

Answer 10

Two copies of each chromosome

Question 11

How are oncogenes affected in cancer cells?

Answer 11

Increased oncogene expression

Question 12

How are tumour suppressor genes affected in cancer cells?

Answer 12

Decreased tumour suppressor gene expression

Question 13

What are the types of chromosomal instability?

Answer 13

Structural

Numerical

Question 14

What can cause numerical chromosomal instability in cancer cells?

Answer 14

Amplified centrosomes

Question 15

What are amplified centrosomes?

Answer 15

Increased number of centrosomes in dividing cell

more than two

Question 16

What is a centrosome made up of?

Answer 16

Pair of centrioles

Question 17

What causes amplified centrosomes?

Answer 17

Uncoupling of centrosome duplication cycle

from cell cycle

Question 18

How do amplified centrosomes affect the mitotic spindle apparatus?

Answer 18

Give a multipolar spindle apparatus rather than a bipolar one

Question 19

What are the consequences of a multipolar spindle apparatus?

Answer 19

Chrosomes pulled apart to multiple poles in the cell
daughter cells have severe aneuploidy
die as a result

Question 20

How do cancer cells with amplified centrosomes survive?

Answer 20

Have developed mechanisms to cluster the extra centrosomes
into two groups
to still form somewhat bipolar spindle apparatus

Question 21

How can some cancer treatments target clustering of amplified centrosomes?

Answer 21

Inhibit the clustering of amplified centrosomes
so multipolar spindle apparatus forms
cancer cells die

Question 22

What is the advantage of targeting clustering of amplified centrosomes over targeting the bipolar spindle apparatus?

Answer 22

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