Mutations
A A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes. is a change in a The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production. or The structure made of DNA that codes for all the characteristics of an organism.. It is a rare, random change in the genetic material and it can be inherited.
Causes of mutation
Mutation occurs continuously and can be spontaneous. It can also happen because of:
- Radiation that is able to remove electrons from atoms or molecules to produce positively charged particles called ions.
- chemical A physical or chemical agent that can induce or increase the frequency of mutation in an organism., such as tar from cigarette smoke
Ionising radiation includes gamma rays, X-rays and ultraviolet rays. The greater the dose of Energy carried by particles from a radioactive substance, or spreading out from a source. a cell gets, the greater the chance of a mutation.
Mutations could cause different genes to be switched on or off, and this could create a different or faulty Organic compound made up of amino acid molecules. One of the three main food groups, proteins are needed by the body for cell growth and repair. to be synthesised. For example, if the protein is an important enzyme, the specific substrate might not fit into the substrate binding site. If it is a structural protein such as collagen, it might lose its strength.
However, most Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being. mutations do not significantly alter a protein, they only alter it slightly, or not at all, so its appearance or function is not changed.
Mutations can be positive and give an organism an advantage or negative and give a disadvantage but mutations that have a significant effect are rare. Some mutations may have a small effect but most mutations have no effect on the organism. They do not change to the organism's The visible characteristics of an organism which occur as a result of its genes..
Image caption, Original gene structure
There are many different types of mutations which can arise in DNA. This diagram shows the normal order of the bases for one of the strands in a DNA molecule. Only one of the strands of DNA is involved in protein synthesis. A change from the normal order of bases leads to different types of gene mutation eg CGA / ACC / CGA.
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These mutations may change the activity of a protein if they occur within a gene. This might result in a change in phenotype or it might appear hidden, and be unnoticed. Alternatively, they might result in a serious consequence, such as genetic disease like cystic fibrosis.
