Genre: Information/Explanation

Look at picture 15 . Part A shows the nucleus of a cell . The nucleus contains genetic material in the form of chromosomes . a ) How many chromosomes does the cell in picture A contain ? b ) Before mitosis , there is an increase in genetic material . Why do you think this happens ? c ) How many chromosomes would each of the new cells ( part C ) have ? d ) Why are the cells formed by motosis genetically identical ? e ) Explain why cancer cells keep growing even though the original mutation happened in only a single cell . What our experts say : a ) 6 . b ) Cell copies all its parts and this includes making a copy of the DNA in its nucleus . Just before a cell splits during mitosis it has double the normal amount of DNA . c ) 6 . d ) During the first stages of mitosis , the cell's DNA makes an exact copy of itself . One copy is passed onto each of the two new cells . This means the two new cells are genetically identical . e ) The cancer is caused by a mutation that happens in just one cell . This is a change in the original cell's DNA that triggers it to grow out of control . The mutation is copied when the DNA is copied during mitosis and so all of the cells that grow from the original cell will contain the mutation . This means that the new cancer cells continue to grow in an uncontrolled way .