some organisms, like bacteria, are single celled.
Most cells can only divide to make more cells of the same kind. Some cells are very special as they can become any type of cell. They are called stem cells.
growth is the permanent increase in the size of an organism.
new cells are made by cell division.
body cells such as teeth, hair, nails skin and muscle are made by a kind of cell division called mitosis. Mitosis produces cells for growth,repair or the replacement of older cells.
most plants keep growing sll their life however animals stop growing when they reach a certain height.
most body cells have a nucleus containing chromosomes. the chromosomes carry genes which control the characteristicsof an organism. before a cell can divide, it must make a copy of all its chromosomes. when the cell splits, each new cell will contain identical chromosomes, carrying identical genes. the new cells are called Daughter cells.
body cells are diploid - they have two copies of each chromosome.
mitosis begins with a single cell.
first the cell makes a copy of each chromosome.
then it divides.
each new cell has a full set of chromosomes and is identical to the original cell.
Original cells - parent cells
Replicated cells - daughter cells (identical to parent cells)
meiosis is growth and repair for gametes (sex cells) only.
a male's sperm determines the gender of the baby (x, y chromosomes)