The Cell Cycle

Cells follow a natural life cycle. Most cells are formed, grow bigger, and then divide. This process is known as the cell cycle and it has two main phases:

1. Interphase (Growing phase, 90%)
2. Mitosis (Dividing phase, 10%)

The cell cycle describes the stages a cell goes through from when it is created to when it divides again.

It covers both the growing phase (interphase) and the dividing phase (mitosis).

1. Interphase

• Interphase is the phase when the cell is not dividing, and it makes up about 90% of the cell cycle.
• During this time, the cell:
  • Grows and carries out its normal functions.
  • Prepares for division by copying its DNA.
• Towards the end of interphase, the chromosomes become visible under a microscope.
• Each chromosome makes an exact copy of itself, forming double-stranded chromosomes (also called sister chromatids).

2. Mitosis

• Mitosis is the phase when the cell actually divides, making up about 10% of the cell cycle.

Mitosis can be broken down into four stages:

3. Prophase
4. Metaphase
5. Anaphase
6. Telophase

Mitosis will be explored in much greater detail in the next note.