Cell Division: Mitosis: Worked Reasoning

Worked Reasoning

Make each reasoning step visible: identify the knowns, choose the governing idea, apply it and check the result.

This extension applies that lens specifically to Cell Division: Mitosis.

Cells divide so that organisms can grow, repair damaged tissue and replace worn-out cells. The type of division that makes ordinary body cells is mitosis.

The cell cycle has two main parts:

1. Interphase - the cell grows and copies (replicates) its DNA, so each chromosome now has two identical chromatids.
2. Mitosis - the copied chromosomes are shared out in four stages, remembered as PMAT:

• Prophase - chromosomes become visible; nuclear membrane breaks down.
• Metaphase - chromosomes line up along the equator (middle) of the cell.
• Anaphase - the chromatids are pulled apart to opposite poles.
• Telophase - two new nuclei form; the cell then splits (cytokinesis).

Mitosis produces two genetically identical daughter cells, each with the same chromosome number as the parent cell.