producing new cells

• what is cell division

  Cell division, or mitosis, helps organisms make more cells. Single-celled organisms use it to reproduce, while multicellular organisms use it for growth and repair.
• Genetic material

  When cells divide, it is essential that genes are copied

  into the new cells. Because it contains the chromosomes, the nucleus controls all the activities of the cell (including cell division).
• Role of Cell Division

  Cell division provides new cells

  for growth

  to repair damaged tissues

  to replace damaged cells
• During cell division, the parent cell divides to produce two identical daughter cells.

  They contain the same number of chromosomes in their nuclei as the parent cell.
• Every species of plant and animal has a definite and

  characteristic number of chromosomes called the chromosome complement, present in each cell.
• The full chromosome complement for normal human

  body cells is 46 or 2 sets (each containing 23 chromosomes)
• Mitosis maintains the diploid chromosome complement so no genetic information is lost.
• A cell’s chromosomes are usually long, thin strands. Just before the cell divides, however, the chromosomes become shorter, thicker and more visible.
• Each chromosome duplicates and becomes two strands, each one called a chromatid. The two chromatids are joined at the centromere.
• During cell division, the parent cell divides to produce two identical daughter cells

  They contain the same number of chromosomes in

  their nuclei as the parent cell
• 1.The number of cells doubles after each

  division.

  2. This is used to calculate the number of cells present after a certain time.
• 1.The number of chromosomes found in a cell is

  called the chromosome complement

  2. Most cells are diploid and have 2 sets of

  matching chromosomes
• Diploid cells

  have a double set of chromosomes which form pairs (2n)

  Normal body cell are diploid, as are zygotes

  (fertilised eggs).

  In humans diploid cells have 46 chromosomes

  (23 pairs).
• Haploid cells

  have a single set of chromosomes (n)

  All normal sex cells (sperm & egg) are haploid. In humans haploid cells have 23 chromosomes
• The type of cell division that makes animals and plants grow is called mitosis.
• Mitosis refers to the division of a cell’s nucleus.
• In mitosis, a parent cell divides into two identical

  daughter cells. These daughter cells divide in two, and so on.
• Chromosomes become visible inside the nucleus of the parent cell