Monika

Cell Cycle Overview

The cell cycle is the process by which a cell grows, prepares for division, and divides to form two daughter cells. It has two main phases:

1. Interphase – the preparation phase (about 90% of the cycle)

2. M Phase (Mitotic Phase) – the division phase

🔹 INTERPHASE – Preparation for division

Interphase is divided into three stages:

🔸 G₁ Phase (Gap 1):

• The first stage after cell division

• The cell grows in size

• It makes proteins and organelles

• The cell prepares for DNA replication

🔸 S Phase (Synthesis):

• The cell replicates its DNA

• Each chromosome becomes two sister chromatids (exact copies)

🔸 G₂ Phase (Gap 2):

• The cell continues to grow

• It makes final preparations for mitosis

• Checks for DNA damage or replication errors

🔹 M PHASE (Mitosis Phase) – Division of the cell

The M phase includes mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).
Mitosis has four stages:

🔸 Prophase:

• Chromosomes condense and become visible

• Nuclear envelope starts to break down

• Spindle fibers begin to form

🔸 Metaphase:

• Chromosomes align at the center (equator) of the cell

• Spindle fibers attach to the centromeres of chromosomes

🔸 Anaphase:

• Sister chromatids are pulled apart toward opposite poles of the cell

• Now, each side has a complete set of chromosomes

🔸 Telophase:

• Chromosomes begin to de-condense

• Nuclear envelopes reform around each set of chromosomes

• Two new nuclei are formed

Then the cell completes cytokinesis, where the cytoplasm divides, forming two daughter cells.

🧾 In summary: