Mutation - A Genetic Change

Mutation Definition

“Mutation is the change that occurs in our DNA sequence due to environmental factors such as UV light, or due to the mistakes caused when the DNA is copied.”

Table of Contents

What Are Mutations?

Our DNA can undergo changes in its base sequences A, C, G and T. This results in the changes in proteins that are synthesised by the DNA. Usually, the cells can recognize any damage that can be caused by mutation and repair it before it becomes permanent.

Types of Mutations

The mutations are of three types:

  • Silent mutation

A change or variations within the sequence of nucleotide bases which constitutes DNA, without a subsequent change in the amino acids or the function of the overall protein.

  • Nonsense mutation

A nonsense mutation occurs when there is a change in the sequence of nucleotides and holds the normal sequence of amino acids in the final protein.

  • Missense mutation

A missense mutation is a type of point mutation, where two different amino acids are placed within the produced protein, other than its original.

Causes of Mutations

The mutation leads to genetic variations among species. Few mutations with a positive effect are transferred to successive generations.

For eg., Sickle cell anaemia is the result of a mutation in the gene that codes for the synthesis of the protein haemoglobin. The red blood cells take a sickle-shape. However, in the African population, this mutation also protects against malaria.

Cancer is the most common disease caused by the mutation in a number of growth controlling cells.

Let us have an overview of the causes and impacts of mutation.

Also Read: Mutagens

The mutation is caused due to the following reasons:

Internal Causes

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.

External Causes

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.


DNA Mutation

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

    1. Few mutations result in new versions of proteins and help the organisms to adapt to changes in the environment. Such mutations lead to evolution.
    2. Mutations in many bacteria result in antibiotic-resistant strains of bacteria that can survive in the presence of antibiotics.
    3. 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

  1. 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.
  2. Cancer is another disease caused by the mutation in genes that regulate the cell cycle.

For more information on mutation, its causes and effects, keep visiting BYJU’S website or download BYJU’S app for further reference.

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