Mutation - A Genetic Change

Mutation Definition

“Mutation is the change in our DNA base pair sequence due to various environmental factors such as UV light, or mistakes during DNA replication.”

Table of Contents

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.

A mutation is a sudden, heritable modification in an organism’s traits. The term “mutant” refers to a person who exhibits these heritable alterations. Mutations usually produce recessive genes.

Classification & Types of Mutations

Mutation Classifications Types Description Examples of Human Disease(s)
Point mutation
Substitution During replication, one base is inserted incorrectly, replacing the pair at the appropriate location on the complementary strand. Sickle-cell anemia
Insertion In replicating DNA, one or more additional nucleotides are added, frequently causing a frameshift. One form of beta-thalassemia
Deletion During replication, one or more nucleotides may be “skipped” or removed, which usually causes a frameshift. Cystic fibrosis
Chromosomal mutation
Inversion The flipping and reinserting of a single chromosomal region. Opitz-Kaveggia syndrome
Deletion When a chromosome segment is lost, all the genes in that segment are also gone. Cri du chat syndrome
Duplication A chromosomal segment is repeated, increasing the concentration of the genes in that area. Some cancers
Translocation A section of one chromosome is inappropriately joined to another chromosome. One form of leukemia
Copy number variation
Gene amplification An increase is made in the tandem copies of a locus. Some breast cancers
Expanding trinucleotide repeat There are more repeating trinucleotide sequences than usual. Fragile X syndrome, Huntington’s disease

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:

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.

Frequently Asked Questions


Give the meaning of mutation.

Mutation means an alteration in the genes or chromosomes of a cell. This shift in the gametes may impact the development and structure of the progeny. A mutation in biology is a modification of the nucleic acid sequence of a virus, extrachromosomal DNA, or the genome of an organism. The observable traits of an organism (phenotype) may or may not change as a result of a mutation.


Define gene mutation. Give examples.

Gene or genetic mutations are modifications to the DNA sequence that take place as the cells divide and generate copies of themselves. The DNA provides instructions on how to develop and run the human body. Genetic changes may result in diseases like cancer or, in the long run, enable people to adapt to their surroundings more successfully.

Examples include animals possessing extra body parts after birth, such as four-legged ducks, cyclops kittens, and snakes with two heads. Genetic disorders in humans, like Sickle-cell disease, are frequently brought on by gene mutations or chromosomal aberrations. Angelman syndrome, Canavan disease, colour blindness, cystic fibrosis, cri-du-chat syndrome, Down syndrome, haemophilia, Klinefelter syndrome, Duchenne muscular dystrophy, phenylketonuria, Prader-Willi syndrome, Tay-Sachs disease, and Turner syndrome are additional examples of common mutations in human beings.


What is DNA mutation?

A DNA mutation is a long-lasting alteration to the nucleotide sequence of DNA that can occur during replication and recombination. Most of the time, mutations are benign unless they result in tumour growth or cell death. Base pair substitution, deletion, or insertion can all result in mutations in damaged DNA. Cells have developed processes for repairing damaged DNA owing to the deadly consequences of DNA mutations.

Base substitutions, deletions, and insertions are the three different forms of DNA mutations.


What are the causes of gene mutation?

A gene mutation is a permanent change to a DNA sequence that makes it different from the sequence found in other people. A genetic mutation occurs during cell division when the grow and divide and replicate. Mutations can impact anything from a single DNA base pair (a unit of genetic composition) to a significant portion of a chromosome that contains numerous genes.


How does mutation affect genetic change?

A population can acquire new alleles through mutations, increasing the genetic diversity of the population. For mutations to impact an organism’s offspring, they must: 1) arise in cells that give rise to the succeeding generation; and 2) alter the genetic code. Diversity among organisms is ultimately produced through the interaction of hereditary mutations and environmental stresses.

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