Chromosome mutations are due to change in either the chromosome structure or the chromosome number of a cell.
A gene mutation is a change in the order of bases on a strand of DNA.
Factors that increase the chances of mutation are called mutagens.
Gene and chromosome mutations occur naturally and generally have a low frequency. However, certain chemicals and rays can increase the rate of frequency of mutation. These are called
mutagenic agents and include:
chemicals such as mustard gas, caffeine and cochineal
irradiation such as U-V radiation, X-rays and gamma rays
Mutations happen naturally but the mutation rate is increased if organisms are exposed to mutagens.
Causes & Effects
Mutations in DNA sequences generally occur through these processes:
• DNA damage from environmental agents such as ultraviolet light (sunshine),
• nuclear radiation (e.g. Chernobyl incident?),
• Mistakes that occur when a cell copies its DNA in preparation for cell division.
• Certain factors can damage DNA by altering nucleotide bases so that they look like other nucleotide bases.
• When the DNA strands are separated and copied, the altered base will pair with an incorrect base and cause a mutation.
–Production of new/ superior protein
Results; gain on reproductive advantage
Results; no change
–Production of inferior or no protein
Results; fatal and/or disease causing