cell cycle

Question 1

what is the cell cycle

Answer 1

highly ordered sequence of events that takes place in a cell, resulting in the divison of the cell, and the formation of 2 genetically identical daughter cells

Question 2

interphase

Answer 2

• DNA is replicated and checked for errors in the nucleus
• protein synthesis occurs in the cytoplasm
• mitochondria grow and divide
• chloroplasts grow and divide
• normal metabolic processes occur (e.g. respiration)

Question 3

interphase G1

Answer 3

• first growth phase
• proteins from which organelles are synthesised are produced
• organelles replicate
• cell size increases

Question 4

interphase S

Answer 4

• synthesis phase
• DNA(chromosomes) are replicated in the nucleus

Question 5

interphase G2

Answer 5

• second growth phase
• cell continues to increase in size
• energy stores are increased
• duplicated DNA is checked for errors and repairs are made

Question 6

difference between mitosis and cytokinesis (mitotic phase)

Answer 6

mitosis- the nucleus divides
cytokinesis- the cytoplasm divides and 2 cells are produced

Question 7

G0

Answer 7

• when the cell leaves the cycle
  due to:
• differentiation (a specialised cell is no longer able to divide)
• DNA is damaged (cell can no longer divide and enters period of permanent cell arrest )
• cells can divide a limited number of times and become senescent
• lymphocytes can be stiumulated to go back into the cell cycle and divide again

Question 8

what are checkpoints

Answer 8

• control mechanism of cell cycle
• monitor and verify whether processes at each stage have been accurately completed before cell progresses into the next stage

Question 9

G1 checkpoint

Answer 9

• at the end of the G1 phase
  check for:
• cell size
• nutrients
• growth factors
• DNA damage

DNA replication is triggered

Question 10

G2 checkpoint

Answer 10

• at the end of G2 phase
  check for:
• cell size
• DNA replication without error
• DNA damage

cell initiates molecular processes that signal the beginning of mitosis

Question 11

spindle assembly checkpoint (metaphase)

Answer 11

• at the point in mitosis where all the chromosomes should be attached to spindles and have aligned
• checks for chromosome attachment to spindle