Two methods of cell division - Mitosis, meiosis!
Cell ---> nucleus with chromosomes in ---> DNA doubles ---> Nucleus disappears and fibre forms ---> fibre pulls chromosomes apart ---> Chromosomes have been sepparated and nucleus reforms to produce two genetically identical cells.
Mitosis is responsible for - Growth, Replacement & Repair.
Mitosis in animals -
- all tissues in the body will undergo mitosis at some stage in their development.
- Some of these tissues are more efficient at this type of cell division e.g. skin cells - have a special layer of that keeps replacing cells that wear away throughout your life.
- Red cells are produced in the bone marrow - mature red blood cells don't posses a nucleus, they had a nucleus at the early stage of development.
- Nerve cells - aren't very good at replacing themselves.
- Animals are able to repair most damaged tissues using mitosis.
Mitosis in plants
- the parts that undergo mitosis are limited to the growing areas.
- Meristems - regions of the plant where growth due to mitosis occurs/responsible for the growth of the roots downwards into the soil and upwards towards light.
- tips of roots and the shoots there are areas of growth to which mitosis is confined.