4. Mitosis

Question 1

mitosis is needed for

Answer 1

growth of multicellular organisms and for repairing damaged tissues

Question 2

not all cells keep ability to divide but ones that do follow a

Answer 2

cell cycle

Question 3

interphase of the cell cycle

Answer 3

gap phase 1 (cell grows and new organelles and proteins made)
synthesis ( cell replicates DNA ready to divide by mitosis)
gap phase 2 cell keeps growing and proteins needed for cell division made)

Question 4

cell cycle

Answer 4

mitosis (starts here)
gap phase 1 
synthesis
gap phase 2 
mitosis (ends here)

Question 5

interphase

Answer 5

cell carries out normal functions but prepares to divide
cells DNA unravelled and replicated
organelles replicated
ATP content increased (provides energy for cell division)

Question 6

1. prophase

Answer 6

chromosomes condense getting shorter and fatter
proteins called centrioles start moving to opposite poles of cell forming network of protein fibres known as spindle
nuclear envelope breaks down and chromosomes lie free in cytoplasm

Question 7

2. metaphase

Answer 7

chromosomes line up along middle of cell and become attached to spindle by centromere

Question 8

3. anaphase

Answer 8

centromere divide separating each pair of sister chromatids
spindles contract pulling chromatids to opposite poles of spindle, centromere first
makes chromatids appear v shaped

Question 9

4. telophase

Answer 9

chromatids reach opposite poles on spindle
uncoil to become long and thin again
now called chromosomes again
nuclear envelope forms around each group of chromosomes so now 2 nuclei
cytoplasm divides (cytokenisis)
2 daughter cells that are genetically identical
each daughter cell now begins interphase

Question 10

cancer

Answer 10

mitosis and cell cycle regulated by genes
mutation in gene that controls cell division= uncontrolled cell growth
cells keep on dividing which eventually forms tumour
cancer is a tumour that invades surrounding tissue

Question 11

some cancer treatments target the

Answer 11

cell cycle

Question 12

examples of cell cycle targets of cancer treatment G1

Answer 12

g1 (cell growth and protein production) some chemical drugs (chemotherapy) prevent syntheis of enzymes needed for DNA replication. if these arent produced cell cant enter syntheis phase, disrupting cell cycle and causing cell to kill itself (apoptosis)

Question 13

examples of cell cycle targets of cancer treatment S phase

Answer 13

(DNA replication)
radiation and some drugs damage DNA
during cell cycle DNA is checked for damage
if damage is detected the cell will kill itself which prevent tumour growth

Question 14

issue with cell cycle cancer treatments

Answer 14

dont distinguish tumour cells from normal cells so also kill normal body cells
tumour cells divide more frequently so the treatment is more likely to kill tumour cells