Only $35.99/year

Terms in this set (58)

- Radiation and mutagenic chemicals increase the mutation rate and cause gentic disease and cancer

- A gene consists of a length of DNA with a base sequence, the different alleles of a gene have slight variations in base sequence, new alleles are formed from other alleles by gene mutation.

- A mutation is a random change to the base sequence of a gene.

- Two factors that can increase mutation rates are:
- Radiation: increases mutation rate if it has enough energy to cause chemical changes in DNA. Gamma rays and alpha particles from radioactive isotopes, short-wave ultraviolet radiation and X-rays are all mutagenic.
- Chemical substances: some cause chemical changes in DNA and therefore are mutagenic. Ex: benzo(a)pyrene and nitrosamines found in tobacco smoke and mustard gas used as a chemical weapon in WW1.

- Ex: consequences of nuclear bombing and accidents at nuclear power stations such as bombing of Hiroshima+Nagasaki and the nuclear accidents at Chernobyl.
- Radioactive isotopes were released, people and the enrvionment were exposed to potentially dangerous levels of radiation.

- A random change to an allele that developed by evolution over millions of years is unlikely to be beneficial, therefore most mutations are harmful or neutral. In these cases little evidence of later impact, but many direct.

- Cancer: mutations of the genes that control cell division can cause them to divide endlessly and develop into a tumour

- Genetic diseases: Mutations in body cells, including those that cause cancer, are eliminated when an individual dies, but mutations in cells that develop into gametes can be passed to offspring. Therefore it is important to minimize the number of mutations in gamete-producing cells in the ovaries and testes.