3.12 - Mitosis

Question 1

What do cancer targeting drugs target within the cell cycle?

Answer 1

• S phase- Some drugs can prevent DNA from replicating.
• Metaphase - Some drugs interfere with the formation of spindle fibres.

these drugs also disrupt the cell cycle of healthy cells. However, tumour cells divide at a faster rate than healthy cells so are more likely to be damaged by these drugs

Question 2

What causes cancer specifically?

Answer 2

Mutations in genes can lead to uncontrolled cell division and growth, resulting in a group of abnormal cells known as a tumour. Tumours become cancerous when they start to invade neighbouring tissues

Question 3

What happens during cytokinesis?

Answer 3

the cytoplasm divides in a process known as cytokinesis. This produces two daughter cells that are genetically identical to one another

Question 4

What happens during telophase?

Answer 4

The chromatids reach the opposite poles of the cell where they uncoil to become long and thin chromosomes again.

A nuclear envelope forms around each set of chromosomes to form two nuclei and the nucleolus starts to reform.

Question 6

What happens during metaphase?

Answer 6

The chromosomes line up at the equator (middle) of the cell.

Each chromosome attaches to the spindle by their centromere.

Question 7

Prophase (what happens):

Answer 7

The chromosomes condense (become shorter and thicker) and are now visible under a microscope.

Centrioles (bundles of protein) migrate to opposite poles (sides) of the cell.Each centriole starts forming spindle fibres.

The nucleolus disappears and the nuclear envelope starts to break down, leaving the chromosomes free in the cytoplasm

Question 8

Order of the stages of mitosis

Answer 8

prophase
metaphase
anaphase
telophase

Question 9

Importance of mitosis (5):

Answer 9

• Growth- Unicellular zygotes can divide by mitosis to form multicellular organisms.
• Replacement of damaged or dead tissues- Cells are constantly dying and being replaced using mitosis.
• Asexual reproduction- Some organisms reproduce using mitosis to form genetically identical offspring.
• Development of body plans- Mitosis is used to form the different parts of an organism.
• Production of stem cells - Stem cells divide by mitosis.

Question 10

What happens during mitosis and cytokinesis?

Answer 10

• Mitosis- The nucleus divides.
• Cytokinesis- The whole cell and cytoplasm divides.