6.4 The Significance of Mitosis

Question 1

What is mitosis?

Answer 1

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

Question 2

What three biological processes are those most significant carried out by mitosis?

Answer 2

Growth of multicellular organisms

Replacement of cells & repair of tissues

Asexual reproduction

Question 3

How is mitosis significant in the growth of multicellular organisms?

Answer 3

The two daughter cells produced are genetically identical to one another (clones) and 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

Question 4

How is mitosis significant in the replacement of cells & repair of tissues?

Answer 4

Damaged tissues can be repaired by mitosis followed by cell division

As cells are constantly dying they 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

Some animals can regenerate body parts, for example, zebrafish can regenerate fins and axolotls regenerate legs and their tail amongst other parts

Question 5

How is mitosis significant in asexual reproduction?

Answer 5

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 a genetically identical offspring

For multicellular organisms, new individuals grow from the parent organism (by cell division) and then detach (‘bud off’) from the parent in different ways

This type of reproduction can be observed in different plant, fungi and animal species

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