Mitosis

Question 1

Explain mitosis

Answer 1

Prophase - chromosomes condense
Get shorter and fatter become visible
Centrioles go to opposite poles of the cells
Releasing spindle fibres that create spindle apparatus
Nucleolus and nuclear envelope break down

Metaphase - chromosomes line up along the equator of the cell by the spindle fibres that are attached to their centromere

Anaphase - centromere divides separating sister chromatids (2)
Spindle fibres contract pulling apart the duster chromatids which are attached by centromere
Sister chromatids travel to opposite poles of the cell

Telophase - chromatids on opposite poles
Uncoil become long and thin
Nuclear envelope and nucleolus form around the chromosomes
Spindle apparatus is distinguished
Division of cytoplasm cytokinesis leads to 2 genetically identical daughter cells

Question 2

What is cancer

Answer 2

Genes that regulate mitosis and the cell cycle are damaged
This leads to uncontrolled growth and division
Abnormal group of cells called tumour produced

Question 3

Why is cancer caused

Answer 3

Mitosis caused but two types of genes if one mutates
Uncontrolled mitos
Mutated cells that survive produce clones

Question 4

Strength and weakness of cancer treatments

Answer 4

They also kill human body cells that are dividing as treatments can’t distinguish between tumour cells and normal cells

But tumour cells divide much more frequently than normal cells so treatments more likely to kill