Stem Cells

This lesson covers stem cells — what they are, where they are found, their potential uses and the ethical issues surrounding them — as required by the AQA GCSE Combined Science Trilogy specification (8464).

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What Are Stem Cells?

A stem cell is an undifferentiated cell that has the ability to:

1. Divide by mitosis to produce more stem cells (self-renewal).
2. Differentiate into one or more types of specialised cell.

Stem cells are the source of all the specialised cells in the body. They are critically important for growth, development and repair.

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Types of Stem Cell

There are different types of stem cell, which vary in their ability to differentiate:

1. Embryonic Stem Cells

• Found in early-stage embryos (typically at the blastocyst stage, a few days after fertilisation).
• Can differentiate into any type of cell in the body — they are described as pluripotent (or sometimes totipotent at the very earliest stage).
• Extremely versatile and are of great interest to medical researchers.

2. Adult Stem Cells