Cell division

The basic structure of most animal and plants cells is shown below.

Animal and plant cells,  The animal cell shows cytoplasm, nucleus and cell membrane. The plant cell also has these, it also has chloroplast, vacuole and cell wall.

All cells are produced from other cells by the process of cell division. Cell division occurs when one cell divides to produce two new cells. Unicellular organisms use cell division to reproduce.

One parent bacterial cell divides into two daughter cells with identical DNA. The combined size of the two daughter cells equals the size of the parent.

Multicellular organisms use cell division for growth and repair of damage such as wounds.

The new cells produced by cell division are genetically identical to the parent cell because they each receive a copy of all the chromosomes it has in its nucleus.

One parent human cell with 46 chromosomes divides into two genetically identical daughter cells each with 46 chromosomes. The combined size of the two daughter cells equals the size of the parent.

Sometimes the cells in part of a multicellular organism divide uncontrollably. The result is a large mass of cells called a tumour. If tumour cells successfully invade other tissues in the body the result is cancer.

A section of skin showing the lower and upper sections plus cells at the surface of the skin. A cell within the upper layer divides and new cells replace dead cells.  Old dead cells at the surface of the skin are discarded.Normal cell division in the skin

Section of skin showing lower and upper sections plus cells at the surface of the skin. A cell within the upper layer divides, a tumour is formed and invades the surrounding tissue, causing cancer.Tumour formation
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