AQA GCSE FOUNDATION Biology: Cell Division and the Cell Cycle

AQA GCSE Foundation Biology: Cell Division and the Cell Cycle

Introduction

All living organisms are made up of cells. For an organism to grow, repair damaged tissues, or reproduce, cells must divide. This process is called cell division. There are two main types of cell division: mitosis and meiosis. In this tutorial, we will focus on mitosis.

Mitosis: The Process of Cell Division

Mitosis is a type of cell division that produces two daughter cells that are genetically identical to the parent cell. This is important for growth, repair, and asexual reproduction.

Mitosis occurs in several stages:

1. Interphase: This is the longest stage of the cell cycle. During interphase, the cell grows and copies its DNA. The DNA is in the form of chromatin, which is a long, thin thread-like structure.

2. Prophase: The chromosomes condense and become visible as short, thick structures. The nuclear membrane breaks down, and the spindle fibers start to form.

3. Metaphase: The chromosomes line up at the center of the cell, attached to the spindle fibers by their centromeres.

4. Anaphase: The centromeres divide, and the sister chromatids separate, moving to opposite poles of the cell.

5. Telophase: The chromosomes reach the poles of the cell, and the nuclear membrane reforms around each set of chromosomes. The spindle fibers break down, and the cytoplasm divides, forming two daughter cells.

Cellular Growth

Before a cell can divide, it needs to grow and increase its size. This involves:

• Producing more cytoplasm: The cytoplasm is the gel-like substance that fills the cell and contains organelles.
• Increasing the number of organelles: Organelles are specialized structures that perform specific functions within the cell.
• Replicating DNA: DNA contains the genetic information for the cell. Before division, the DNA must be copied so that each daughter cell receives a complete set of genetic information.

Importance of Mitosis

Mitosis is an essential process for all living organisms. It is involved in:

• Growth: As organisms grow, they increase the number of cells through mitosis.
• Repair: Mitosis helps to repair damaged tissues by replacing damaged or dead cells with new ones.
• Asexual reproduction: Some organisms, such as bacteria and plants, reproduce asexually. This means that they produce offspring that are genetically identical to the parent. Mitosis is the process that enables this type of reproduction.

Summary

Cell division, particularly mitosis, is crucial for the growth, repair, and reproduction of living organisms. The process involves several stages, each with specific events that ensure the accurate replication of genetic material and the creation of two identical daughter cells. Understanding the cell cycle and mitosis is essential for comprehending the fundamental processes of life.