Mitosis (Cambridge International AS Biology)

The Importance of Mitosis

Spec point — 5.1.2 · explain the importance of mitosis in the production of genetically identical daughter cells during: • growth of multicellular organisms • replacement of damaged or dead cells • repair of tissues by cell replacement • asexual reproduction

The importance of mitosis

• Mitosis is the process of nuclear division by which two genetically identical daughter nuclei are produced that are also genetically identical to the parent nucleus
• The process of mitosis is of great biological significance and is fundamental to many biological processes:

Growth of multicellular organisms

• The two daughter cells produced are genetically identical to one another (clones)
• They have the same number of chromosomes as the parent cell
• This enables unicellular zygotes (as the zygote divides by mitosis) to grow into multicellular organisms
• Growth may occur across the whole body of the organism or be confined to certain regions, such as in the meristems (growing points) of plants

Replacement of cells & repair of tissues

• Damaged tissues can be repaired by mitosis followed by cell division

• Dead and damaged cells need to be continually replaced by genetically identical cells

  • In humans, for example, cell replacement occurs particularly rapidly in the skin and the lining of the gut

Asexual reproduction

• Asexual reproduction is the production of new individuals of a species by a single parent organism

  • The offspring are genetically identical to the parent

• For unicellular organisms such as Amoeba, cell division results in the reproduction of genetically identical offspring

• For multicellular organisms (as seen with many plant species) new individuals grow from the parent organism (by cell division) and then detach (‘bud off’) from the parent in different ways

  • Some examples of these are budding in Hydra and yeast and runners from strawberries

Runners from strawberry plants are an example of asexual reproduction. The new strawberry plants that grow from these runners are genetically identical to the parent plant

Exam Hint Be mindful of the terminology here; dead and damaged cells are replaced to repair tissues. Do not make the mistake in an exam of saying that damaged cells are repaired.