Chromosones And Mitosis

Question 1

What is the cell cycle

Answer 1

• Body cells divide to produce new cells as part of a series of stages called the cell cycle
• The stage of the cell cycle when the cell divides is called mitosis
• multicellular organisms use mitosis to grow and develop or replace cells that have been damaged
• the end of the cell cycle results in two new cells identical to the original cell with the same number of chromosomes

Question 2

What are the two main stages of f the cell cycle

Answer 2

• growth and DNA replication
• Mitosis

Question 3

Explain Growth and DNA replication

Answer 3

• in a cel that’s not dividing, the DNA is all spread out in long strings
  1) the cell grows and increases the amount of sub cellular structures such as mitochondria and ribosomes
  2) It then duplicates its DNA - so there’s one copy for each new cell
  3) The DNA is copied and forms X-shaped Chromosomes
  4) Each ‘arm’ of the chromosome is an exact duplicate of the other

Question 4

Explain mitosis

Answer 4

• Once its contents and DNA have been copied, the cell is ready for mitosis
  1) The chromosomes line up at the centre of the cell and cell fibres pull them apart.
  2) The two arms of each chromosome go to opposite ends of the cell
  3) Membranes form around each of the sets of chromosomes (these become the nuclei of the 2 new cells)
  4) The nucleus has divided
  5) lastly, the cytoplasm and cell membrane divide
  6) The cell has now produced 2 new daughter cells
  7) the daughter cells contain exactly the same DNA - They’re identical. Their DNA is also identical to the parent cell