Mitosis

Question 1

Give three uses for mitosis in living organisms

Answer 1

1. Growth
2. Repair
3. Reproduction (asexual)

Question 2

Give the names of the four phases in mitosis

Answer 2

Prophase

Metaphase

Anaphase

Telophase

Question 3

Describe what happens in prophase

Answer 3

1. The chromosomes condense and become visible in the nucleus.
2. The nucleolus disappears and the nuclear membrane breaks down
3. Centrioles move to the opposite poles of the cell
4. Proteins produce spindle fibres which attatch to the centromeres of the chromosomes and begin to move the chromosomes to the equator of the cell

Question 4

Describe what happens in metaphase

Answer 4

1. The spindle apparatus is completely formed
2. The chromosomes are all lined up at the equator of the cell

Question 5

Describe what happens in anaphase

Answer 5

1. The centormeres holding the sister chromatids togehter splits
2. The spindle fibres shorten pulling the sister chormatids apaprt to opposite poles of the cell
3. The chromatids form ‘V’ shapes as they are being dragged by the centromere through the liquid cytosol

Question 6

Describe what happens in telophase

Answer 6

1. The chromatids have now reached the opposite poles of the cell and are now chromosomes
2. The spindle apparatus breaks down
3. The nuclear membrane reforms around the chromosomes at each pole of the cell
4. The chromosomes uncoil into chromatin state
5. The nucleolus reappears in each nucleus
6. Cytokinesis begins

Question 7

Describe what happens in cytokinesis

Answer 7

1. The central cell membrane is pulled inwards by the cytoskeleton
2. This creates a cleavage furrow which gradually deepens until the cell membranes fuse in the middle to form two individual cells