Mutations

1. Mutations • 3.29 Recall that mutation is a rare, random change in genetic material that can be inherited. • 3.31 Understand that many mutations are harmful but some are neutral and a few are beneficial. • 3.33 Understand that the incidence of mutations can be increases by exposure to ionizing radiation (e.g. gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (e.g. chemicals in tobacco).

2. 3.29 Recall that mutation is a rare, random change in genetic material that can be inherited. • A mutation is a change in the DNA of a cell. • It can happen in individual genes or in whole chromosomes. • Sometimes, when DNA is replicating, mistakes are made and the wrong nucleotide is used. • This results in a gene mutation and it can alter the sequence of the bases in a gene. • This then can lead to the gene coding for the wrong protein.

3. There are several ways in which gene mutations can occur: • Duplication of a nucleotide • Nucleotide inserted twice • Deletion of a nucleotide • A nucleotide is missed out • Substitution of a nucleotide • A different nucleotide is used • Inversion of a triplet • The sequence of the bases in a triplet is reversed.

4. 3.31 Understand that many mutations are harmful but some are neutral and a few are beneficial. • Sometimes a gene mutation can be advantageous to an individual. • This can be due to a random mutation. • For example: a bacteria can become resistant to antibiotics.

5. 3.33 Understand that the incidence of mutations can be increases by exposure to ionizing radiation (e.g. gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (e.g. chemicals in tobacco). • Gene mutations are random events that occur is all organisms. • The rate at which they occur can be increased by a number of agents called mutagens. • Mutagens include: • Ionising radiation (UV light, X-rays and gamma rays) • Some chemicals • Mustard gas • Nitrous oxide • Cigarette smoke and tar • Some chemicals from burnt food