cell cycle

Question 1

g1 phase (growth phase - interphase)

Answer 1

• accumulation of ATP + DNA nucelotides in preperation for DNA replication (S phase)
• cell enlargement (increasing cell size)

Question 2

G2 phase (growth phase 2 - interphase)

Answer 2

• ATP replenishment, cytoskeleton dismantles in preperation for mitosis
• cell continues to grow

Question 2

checkpoint 1 (g1)

Answer 2

• check if cell is an appropriate size + growth conditions (sufficent DNA nucelotides + ATP)
• checks for mutations

Question 3

S phase (synthesis phase- interphase)

Answer 3

• DNA replication occurs

Question 4

Check point 2 (G2)

Answer 4

• genome is checked to ensure all chromosomes have been replicated
• checks for mutations
• presence of MPF

Question 5

M phase (mitosis)

Answer 5

• begins due to an increase in MPF

Question 6

checkpoint 3 (M - right before anaphase)

Answer 6

• checks that spindle fibres are attached to centromere
• lowers MPD to initate anaphase

Question 7

regulation of cell cycle (external factors)

Answer 7

-growth factors (hormones)
(bind to complementary recpetors on the cell membrane of target cells. enables relay protein to send message to nucleus
- anchorage dependance: cells must be anchored to extracellular surface to divide
- density dependence: cells require space to divide
- nutrient avaliability
- Temperature, pH

Question 8

regulation of cell cycle (internal factors)

Answer 8

-CDK is an enzyme which is constant throughout the cell cycle, as an increase in cyclin (protein) the CDK and cyclin produce and enzyme-substrate model creating MPF, an increase in MPF initiates M phase, a decrease in MPF initiates anaphase
- cell size +SA:V

Question 9

factors increasing cancer

Answer 9

• ionising radiation
  -mutagenic chemicals
• carcinogens

Question 10

CANCER

Answer 10

-cyclin, and CDK are synthesised from proto-oncogenes and tumour suppressor genes
- if cells are faulty they go through apoptosis (cell death)