Genetic Mutation: Definition, Steps, Types and Examples

What Is a Mutation?

A mutation is a change in the DNA sequences of an organism. Mutation meaning involves alterations in the genetic code, resulting in changes to traits or functions in an organism. It may be spontaneous or induced through environmental changes. Mutation is a major source of genetic variation.

What Is a Genetic Mutation?

A nucleotide mutation, or change, in the DNA of an organism refers to genetic mutations. It may occur due to internal or external factors. These mutations may cause alterations in characteristics, which are one of the very important factors for evolution since they introduce genetic diversity on which natural selection can act.

Classifications and Types of Mutations

In general, these can be classified based on the nature and extent of the change in genetic material.

Point Mutations

Point mutations affect a single nucleotide.

Types:

• Substitution, where one nucleotide is replaced by another

• Insertion, where one or more nucleotides are added

• Deletion, where one or more nucleotides are removed

Chromosomal Mutations

Chromosomal mutation takes place at larger-scale changes.

Types:

• Deletion, by which a chunk of the chromosome is lost

• Duplication, where part of a chunk is duplicated

• Inversion, where a section of a chromosome is bent in the wrong direction.

• Translocation, in which part of a chromosome is transferred from one chromosome to another.

Spontaneous Mutations

• These arise as a result of natural factors

• Results from errors during DNA replication

Induced Mutations

• Induced mutations are a result of exogenous effects

• Examples include chemicals or radiation

• Known as mutagens

Causes Of Mutations

Various environmental and biological factors may cause the mutations to occur.

Environmental Factors

Irradiation such as UV light, X-rays, and radioactive materials causes damage to the DNA hence causing mutations. Chemical compounds, such as benzene and asbestos, and some medications can also be known to cause mutations through genetic alteration.

Biological Factors

Biological factors are due to mistakes made when DNA replication occurs during cell division which leads to mutation. Viral infections occur whenever the virus infects a host and its genetic material is incorporated into the host's DNA thereby causing mutations. These mutations account for the overall genetic variation which drives evolution.

Effects of Mutations

The effects of mutations will depend on their nature and location in the genome.

Beneficial Mutations

• Selective Advantages: Some of the mutations give advantages to survival or reproductive capabilities.The classic example is resistance to antibiotics in bacteria. Some mutations might allow survival in the presence of antibiotics.

Deleterious Mutations

• Genetic Disorders: Mutation can cause sickle cell anemia, and other severe disorders that cause poor health, such as cystic fibrosis.

Neutral Mutations

• Silent Mutations: There would be no effect on the function of the protein. Such a mutation would seem to have very little or no effect at all on the organism.

Role of Mutation in Evolution

Role of mutation in evolution includes:

• Introduces genetic diversity

• Provides raw material for natural selection

• Essential for evolutionary change

• Without mutation, evolution would not occur

Mutation NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Classification and types of mutations

• Causes and effects of mutations

Practice Questions for NEET

Q1. What is not true for genetic code?

1. It is nearly universal

2. It is degenerate

3. It is unambiguous

4. A codon in mRNA is read in a non-contiguous fashion

Correct answer: 4) A codon in mRNA is read in a non-contiguous fashion

Explanation:

DNA or mRNA sequences and amino acid sequences are connected through the genetic code, where each triplet of nucleotides, called a codon, encodes one of the 20 amino acids (e.g., glutamic acid, methionine, phenylalanine, serine, tryptophan, tyrosine, etc.). There are 64 codons in total, and the genetic code is read in a continuous and non-overlapping manner. The statement that codons are read in a "non-contiguous manner" is false, as codons are read sequentially without any spaces or interruptions between them. This continuous reading ensures that each codon is translated directly into an amino acid without any punctuation or gaps.

Hence, the correct answer is option 4) A codon in mRNA is read in a non-contiguous fashion

Q2. A Transition or transversion mutation could result due to

1. Base pair mutation

2. Silent mutation

3. Nonsense mutation

4. Missense mutation

Correct answer: 1) Base pair mutation

Explanation:

Mutations are changes in the DNA sequence that can affect gene expression and function. In addition to base-pair substitutions, mutations include insertion (addition of one or more nucleotides) and deletion (removal of nucleotides), which can cause frameshifts. Mutations can also be classified as silent, missense, or nonsense based on their impact on protein synthesis. These changes are significant in evolution, genetic disorders, and the understanding of cellular processes. Base-pair substitution is of two types:

• Transition mutation: When one purine is replaced by another purine or one pyrimidine is replaced by another pyrimidine.

• Transversion mutation: When one purine is replaced by a pyrimidine and vice versa.

Hence, the correct answer is option 1) Base pair mutation.

Q3. Which of the following is a type of gene mutation

1. Deletion

2. Addition

3. Substitution

4. All of these

Correct answer: 4) All of these

Explanation:

Type of gene mutation:

• Deletion: This is a type of mutation where one or more nucleotide bases are removed from the DNA sequence.

• Addition: This is when one or more nucleotide bases are added to the DNA sequence.

• Substitution: This occurs when one nucleotide base is replaced by another in the DNA sequence.

Hence, the correct answer is option 4)All of these

Also Read-

• MCQ on types of Mutation

• RNA Splicing

• Embryo Development

Video recommended on Genetic Mutation