2: Mutations

A mutation is a random change in the amount of, or arrangement of, the genetic material in a cell. DNA muations are changes to genes due to changes in nucleotide base sequences. 

• Mutagens, found in tar (in tobacco), UV light, X-rays, and gamma rays, cause mutations.
• Mutations associated with mitosis are called somatic mutations and are not passed to offspring.
• Mutations associated with meiosis and gamete formation can be inherited and passed down.

There are point mutations (substitutions), and insertion/deletion mutations, which cause a frame shift.

• Sickle-cell anaemia, andcystic fibrosis are both caused by DNA mutations.
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