3.5 Summary

3.5 Summary (ESG5Y)

Mitosis and the cell cycle

• During interphase the DNA replicates.
• The process of mitosis occurs in four stages: prophase, metaphase; anaphase and telophase.
• Cytokinesis differs in plant and animal cells. In animal cells the cytoplasm invaginates and divides the cell in two, and in a plant cell the cell is divided in two by the cell plate which forms the cell wall.
• Mitosis ensures growth of tissues and organisms.
• Damaged and worn out tissues are repaired and replaced by new cells through mitosis.
• Single-celled (unicellular) organisms like amoeba often reproduce asexually by mitosis.

Cancer

• Cancer is caused by DNA mutations.
• Abnormal and uncontrolled cell division results in tumour formation.
• Tumours affect the functioning of the tissue or organ.
• Cancer cells can enter the bloodstream or lymph and spread to distant parts of the body and form new tumours (metastasise).
• Cancers are caused by substances called carcinogens.
• Carcinogens such as certain chemicals, radiation, viruses and genetics can be the cause of certain cancers.
• Cancers can be treated by various methods including surgery, radiation, chemotherapy and traditional medicines.