Mitosis

Question 1

What is cell division?

Answer 1

• the parent cell divides into produce two genetically identical daughter cells
• mitosis is needed for growth in multi cellular organisms and for repairing damaged tissues
• in multicellular organisations not all cells keep their ability to divide

Question 2

What is the cell cycle?

Answer 2

• The cell cycle consists of a period of cell growth and DNA replication called interphase
• mitosis happens after that
• interphase is subdivided into three separate cell growth stages called G1, S and G2

Question 3

What are the stages of mitosis?

Answer 3

• interphase which is not a division stage
• prophase
• metaphase
• anaphase
• telophase

Question 4

What is interphase?

Answer 4

• The cell carries out normal functions while preparing to divide
• the cells DNA is unraveled and replicated to double its genetic content
• the organelles are replicated so it has spare ones
• the ATP content is increased which provides energy for cell division

Question 5

What is prophase?

Answer 5

• chromosomes condense getting shorter and fatter
• tiny bundles of protein called centrioles start moving to opposite ends of the cell forming a network of protein fibres across it called the spindle
• the nuclear envelop breaks down and chromosomes lie free in the cytoplasm

Question 6

What is metaphase?

Answer 6

-The chromosomes which each have two chromatids lie along the middle of the cell and become attracted to the spindle fibre by their centromere

Question 7

What is anaphase?

Answer 7

• the centromeres divide separating each pair of sister chromatids
• the spindles contract pulling chromatids to opposite poles of the spindle by the centromere
• the chromatids appear v shaped

Question 8

What is telophase?

Answer 8

• the chromatids reach opposite poles on the spindles
• they uncoil and become long and thin again (they are now chromosomes)
• a nuclear envelope forms around each group of chromosomes so there’s two nuclei
• they cytoplasm divides producing two daughter cells that are genetically identical the daughter cells start mitosis

Question 9

How do you calculate how long each stage of mitosis lasts?

Answer 9

• find how many cells are in metaphase out of the amount of visible cells
• find out how long the cell cycle lasts in minuets
• divide amount of cells by the amount of cells visible and times by the time the cell cycle lasts

Question 10

How is cancer related to cell division?

Answer 10

• mitosis and the cell cycle are controlled by genes
• when cells divide enough times to make a new cell they usually stop dividing but if there’s a mutation in the gene controlling cell division the cells can grow out of control
• the cells eventually forms a tumour

Question 11

How do some cancer treatments target the cell cycle?

Answer 11

• Some treatments for cancer are designed to control the rate of cell division in tumour cells by disrupting the cell cycle which kills tumour cells
• the treatments will also kill normal body cells but is more likely to kill tumour cells

Question 12

How do cancer treatments affect G1?

Answer 12

• some chemical drugs prevent the synthesis of enzymes needed for DNA replication
• without the enzymes the cell is unable to enter the synthesis phase disrupting the cell cycle to force the cell to kill itself

Question 13

How do cancer treatments affect the S phase?

Answer 13

• radiation and some drugs damage DNA
• the DNA in the cell is checked for damage several times during the cell cycle
• if severe damage is detected the cell will kill itself preventing further tumour growth

Question 14

What is cancer?

Answer 14

A tumour that invades surrounding tissue