Why cell division matters

Understand the idea

Cell division is required for growth, repair, and reproduction in every living creature. Unicellular organisms reproduce by binary fission. Multicellular organisms use division to make gametes and to add or replace body cells. Without control, division can contribute to cancer.

Division renews damaged cells, produces new cells from older ones, keeps a working chromosome set, and increases cell number for growth. In plants, mitosis also builds new organs and repairs wounded parts. Meiosis is the special path that halves chromosomes for sexual reproduction.

Mitosis forms genetically identical sister chromatids and two daughters with the parent number. Meiosis pairs homologues, allows crossing over, and yields four daughters with half the count. Those two outcomes must not be swapped in an exam answer.

What to remember

• Uses: growth, repair, reproduction, development.
• Mitosis: two identical cells, same chromosome number.
• Meiosis: four haploid cells, half the number, variety.

Recap

Ask what the new cells are for. Body growth and repair point to mitosis. Gametes and halved chromosomes point to meiosis.