Difference Between Gene Mutation and Chromosome Mutation

The key difference between gene mutation and chromosome mutation is that the gene mutation causes alteration of the nucleotide sequence of a gene while the chromosome mutation causes a structural change of the segment of a chromosome including many genes.

Mutations are the permanent alterations of the nucleotide sequences of the genetic material of organisms. Gene mutations and chromosome mutations are two basic types of mutations, and they vary from each other mainly in the magnitude of the alteration. Mutations occur due to many reasons such as erratic steps in regulation of DNA replication and transcription, exposure to radiations, UV light, due to cigarette smoke, due to viral and bacterial infections, etc.

Substitutions, insertions, deletions, or duplications of DNA sequences are the main mechanisms which change the nucleotide sequences. Some mutations go from parent to offspring when they occur in germ cells while some are nonhereditary. Furthermore, some mutations do not change the resulting amino acid sequences. Hence they are silent mutations. However, mutations may or may not be favourable for the persistence in the world over a long time. Individuals or populations with favourable genes will survive while the unfavourable characters arose due to mutations will eliminate from the environment by natural selection.

CONTENTS

1. Overview and Key Difference
2. What is Gene Mutation
3. What is Chromosome Mutation
4. Similarities Between Gene Mutation and Chromosome Mutation
5. Side by Side Comparison – Gene Mutation vs Chromosome Mutation in Tabular Form
6. Summary

What is Gene Mutation?

Gene mutation is a small-scale alteration of the genetic material of an organism, which primarily occurs in a particular gene. Point mutations and frameshift mutations are the two main types of gene mutation in which frameshift mutations take place either as deletions or insertions. When the nucleotide sequence of a gene alters, it causes the changes in the mRNA sequence. Hence, the codon sequence of the gene changes and results in a wrong amino acid sequence. In the end, it produces a wrong protein. Point mutations can be a transition, transversion, silent, missense, and nonsense.

Gene mutation may lead to the alteration of the number or the structure of the entire chromosome, which could be lead to chromosomal mutations. However, gene mutations are small-scale alterations in the nucleotide sequence, and hence they are sometimes corrected through gene regulatory and repair mechanisms. However, some gene mutations remain without repairing. Sickle cell anaemia, haemophilia, cystic fibrosis, Huntington syndrome, Tay-Sachs disease, many cancers and lactose intolerance are some of the diseases occur due to gene mutations.

What is Chromosome Mutation?

Chromosome mutation is a large-scale alteration of the chromosomes of an organism, where either the number or the structure of the chromosomes changes. There are three main types of chromosomal mutations namely duplications, inversions, and deletions. When a particular part of the DNA strand duplicates, the number of genes in a chromosome will increase. It causes both structural and numerical alteration in the chromosome.

Sometimes a portion of a chromosome, which contains several genes in the DNA strand removes and rejoins inversely to the original position. This is known as an inversion, and it is a type of chromosome mutation. Inversions do not cause the number to change, but different interactions may result as the gene order has been changed. Hence, the phenotypes become different or abnormal. Deletions may take place due to exposure to radiation, high heat, or viruses. Usually, deletions are results of external causes, and the affected area of the chromosome determines the extent of change or the damage.

All these chromosomal mutations seriously affect the structure and the number of chromosomes in an organism. They lead to the alteration of protein synthesis and gene expression. Prader-Willi Syndrome and Cri-du-chat syndrome are some of the examples of chromosome mutations caused due to deletions.

What are the Similarities Between Gene Mutation and Chromosome Mutation?

• Gene mutation and chromosome mutation are two types of mutations.
• In both cases, the nucleotide of the DNA sequence changes.
• Both cause for an alteration of gene expression.
• They can lead to genetic diseases.

What is the Difference Between Gene Mutation and Chromosome Mutation?

When alteration of the nucleotide sequence of a gene occurs, it is known as a gene mutation. On the other hand, when the chromosome structure and number change, it is a chromosome mutation. This is the fundamental difference between gene mutation and chromosome mutation. Gene mutation is a small scale mutation which can be point mutation or frameshift mutation. Chromosome mutations can cause due to deletions, translocations, inversions, etc. The number of genes involved makes the key difference between gene mutation and chromosome mutation. In gene mutation, a particular gene mutates while in chromosome mutation, many genes mutate along with the segment of the chromosome.

The below infographic tabulates more details on the difference between gene mutation and chromosome mutation

Summary – Gene Mutation vs Chromosome Mutation

Gene mutation and chromosome mutation are two types of mutations occur in the genetic material of an organism. Gene mutation is an alteration of a nucleotide sequence of a gene while chromosome mutation is an alteration of the nucleotide sequence of a segment of a chromosome. Furthermore, chromosome mutation causes structural as well as numerical changes of the chromosomes. Gene mutations are small scale, and they can be corrected. But chromosome mutations are large-scale serious alterations that cannot be corrected easily. This is the difference between gene mutation and chromosome mutation.

Reference:

1.Nature News, Nature Publishing Group. Available here 
2.“Chromosome Abnormality.” Wikipedia, Wikimedia Foundation, 14 July 2018. Available here 

Image Courtesy:

1.”Point mutations-en”By Jonsta247 – Own work, (CC BY-SA 4.0) via Commons Wikimedia 
2.”Chromosomes mutations-en”By GYassineMrabetTalk (Public Domain) via Commons Wikimedia