“Mutation is the change in our DNA base pair sequence due to various environmental factors such as UV light, or mistakes during DNA replication.”
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What Are Mutations?
The DNA sequence is specific to each organism. It can sometimes undergo changes in its base-pairs sequence. It is termed as a mutation. A mutation may lead to changes in proteins translated by the DNA. Usually, the cells can recognize any damage caused by mutation and repair it before it becomes permanent.
Types of Mutations
The mutations are of three types:
- Silent mutation
It refers to any change in the sequence of DNA, which has no further impact on the amino acid sequence in a protein or in the functions performed by a protein. There is no phenotypic indicator of mutation.
- Nonsense mutation
When due to a point mutation there is change in the sequence of base pair leading to stop codon. It results in a shortened or non-functional protein.
- Missense mutation
A missense mutation is a result of point mutation leading to change in the codon, which then codes for another amino acid.
Causes of Mutations
The mutation leads to genetic variations among species. Positive mutations are transferred to successive generations.
E.g. Mutation in the gene coding for haemoglobin causes sickle cell anaemia. The R.B.Cs become sickle in shape. However, in the African population, this mutation provides protection against malaria.
A mutation in the gene controlling the cell division leads to cancer.
Let us have an overview of the causes and impacts of mutation.
Also Read: Mutagens
The mutation is caused due to the following reasons:
Most of the mutations occur when the DNA fails to copy accurately. All these mutations lead to evolution. During cell division, the DNA makes a copy of its own. Sometimes, the copy of the DNA is not perfect and this slight difference from the original DNA is called a mutation.
When the DNA is exposed to certain chemicals or radiations, it causes the DNA to break down. The ultraviolet radiations cause the thymine dimers to break resulting in a mutated DNA.
Effects of Mutation
There are several mutations that cannot be passed on to the offsprings. Such mutations occur in the somatic cells and are known as somatic mutations.
The germline mutations can be passed on to successive generations and occur in the reproductive cells.
Let us have a look at some of the effects of mutation:
Beneficial Effects of Mutation
- Few mutations result in new versions of proteins and help the organisms to adapt to changes in the environment. Such mutations lead to evolution.
- Mutations in many bacteria result in antibiotic-resistant strains of bacteria that can survive in the presence of antibiotics.
- A unique mutation found in the population of Italy protects them from atherosclerosis, where fatty materials build up in the blood vessels.
Effects of Mutations
- Genetic disorders can be caused by the mutation of one or more genes. Cystic fibrosis is one such genetic disorder caused by the mutation in one or more genes.
- Cancer is another disease caused by the mutation in genes that regulate the cell cycle.
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