Key Difference – Chromosomal Aberration vs Gene Mutation
Chromosomes are definite structures made up of long DNA strands. In a cell, there are 46 chromosomes in 23 pairs. A chromosome contains thousands of genes. Gene is a specific region of a chromosome or specific DNA fragment which bears a genetic code to synthesize a protein. It has a unique DNA sequence. Chromosomes and genes decide the genetic information of a person. Hence, it is very important to keep them intact and precise. However, due to many reasons, chromosomes and genes can be mutated, which can lead to various disease conditions. Chromosomal aberration is an abnormal condition of the chromosome number and structure that causes complications. Gene mutation is a permanent alteration of the DNA sequence of the gene. The key difference between chromosomal aberration and gene mutation is that chromosomal aberration refers to a change in a chromosome number or structure while gene mutation is an alteration of the sequence of the gene which can cause changes in genetic code. A chromosomal aberration always refers to a change in a large segment of a chromosome, containing more than one gene region.
CONTENTS
1. Overview and Key Difference
2. What is Chromosomal Aberration
3. What is Gene Mutation
4. Side by Side Comparison – Chromosomal Aberration vs Gene Mutation
5. Summary
What is Chromosomal Aberration?
Chromosomes are threadlike structures which provide space to thousands of genes in the form of DNA sequences. Various organisms have a specific chromosome number and structure. The entirety of chromosomes represents the genetic information of an organism. Hence, chromosome number and structure are very important. If there is a change in chromosome number and structure, it is known as a chromosome aberration, chromosomal anomaly, chromosomal abnormality or chromosome mutation. It can occur due to a loss, gain or rearrangement of a portion of a chromosome or due to a missing or extra complete chromosomes. These chromosomal abnormalities are also passed to the next generations (offspring).
Types of Chromosomal Aberration
There are four major types of chromosomal aberrations named deletion, duplication, inversion and translocation.
Deletion – When a big segment of chromosome is lost, it is known as deletion.
Duplication – When a segment of chromosome is repeated twice, it is known as duplication.
Translocation – When one segment of a chromosome is transferred into a non-homologous chromosome, it is known as the translocation.
Inversion – When a segment of chromosome is changed at 1800 rotation, it is known as inversion.
All these changes are responsible for the changes in the intact chromosome structure and overall genetic balance of the organism.
Numerical chromosomal aberrations mostly occur due to errors of cell division following meiosis or mitosis. Chromosomal nondisjunction is the main reason for the abnormal number of chromosomes in gametes and in offspring. This situation is known as aneuploidy (presence of an abnormal number of chromosomes). Some gametes are produced with missing chromosomes while some gametes have with extra chromosomes. Both instances create offspring with an unusual number of chromosomes. If the changes occur in egg cells or sperms, those anomalies are transmitted to every cell of the body.
Chromosome anomalies can happen randomly or can be inherited from parents. The origin of these anomalies can be detected by performing chromosomal studies on both babies and parents.
Figure 01: Chromosome Aberrations
What is Gene Mutation?
A gene is a specific region of DNA sequence located on a chromosome which encodes for a particular protein. A permanent alteration of the DNA sequence of the gene is known as a gene mutation. A specific DNA sequence represents the unique genetic code of that protein. Even a single base pair substitution can change the genetic code of the gene, which can ultimately produce a different protein. They are known as point mutations and is the common type of gene mutation. There are three types of point mutations named silent mutation, missense mutation, and nonsense mutation.
Gene mutations can also occur due to insertion or deletion of base pairs from the original gene sequence. These mutations are vital due to their ability to change the template DNA and shift the reading frame, which decides the amino acid sequence of the protein.
Types of Gene Mutations
There are two types of gene mutations named heredity mutations and acquired mutations.
Heredity mutations are inherited from parent to offspring. These mutations are located in gametes of the parents such as egg cells and sperms. Hence they are referred to as germline mutations. When games fertilize, zygote receives the gene mutations and passes to every cell of the offspring body.
Acquired mutations occur in certain cells or certain period during the person’s life. They are mainly caused due to environmental factors such as UV radiation, toxic chemicals, etc. and happen mostly in somatic cells. Hence, acquired mutations are not passed to the next generation.
Figure 02: Gene mutation due to UV radiation
What is the difference between Chromosomal Aberration and Gene Mutation?
Chromosomal Aberration vs Gene Mutation |
|
| Chromosomal aberration is any change in the number and structure of chromosomes in an organism. | Gene mutation is an alteration that occurs in the DNA base sequence of a gene. |
| Changes to the Total Number of Chromosomes | |
| Chromosomal aberration can change the total number of chromosomes in an organism | Gene mutation does not cause changes to the total number of chromosomes in an organism. |
| Scale | |
| Chromosomal aberration can include many gene alterations. | Gene mutation commonly refers to a single gene alteration. |
| Damage | |
| Damages due to chromosomal aberration are large scale compared to gene mutation. | Nucleotide damage is small in scale compared to chromosomal aberration. However, it can cause serious health problems. |
Summary – Chromosomal Aberration vs Gene Mutation
Genes are the specific DNA segments comprised of unique base sequences in chromosomes. There are thousands of genes in a single chromosome. The base sequence of the gene can be altered due to various factors. Any change in the base pair sequence of the gene is known as gene mutation. Gene mutation results in different protein than it encodes. Chromosomal aberration refers to a numerical or structural change of chromosomes of an organism. Numerical abnormalities cause various syndrome conditions in humans. Structural aberrations are mainly due to deletions, duplications, inversions and translocations. A big portion of the chromosome including many genes are changed during the chromosomal abnormality or mutation. This is the difference between chromosomal aberration and gene mutation.
References
1. “What is a gene mutation and how do mutations occur? – Genetics Home Reference.” U.S. National Library of Medicine. National Institutes of Health, n.d. Web. 22 May 2017. https://ghr.nlm.nih.gov/primer/mutationsanddisorders/genemutation
2. “4 Major Types of Chromosomal Aberrations (1594 Words).” YourArticleLibrary.com: The Next Generation Library. N.p., 23 Feb. 2014. Web. 22 May 2017. <http://www.yourarticlelibrary.com/biology/4-major-types-of-chromosomal-aberrations-1594-words/6448/>
Image Courtesy:
1. “Schematic illustration of chromosomal aberrations” By Philippe Hupé – Emmanuel Barillot, Laurence Calzone, Philippe Hupé, Jean-Philippe Vert, Andrei Zinovyev, Computational Systems Biology of Cancer Chapman & Hall/CRC Mathematical & Computational Biology , 2012 (CC BY-SA 3.0) via Commons Wikimedia
2. “DNA UV mutation” By derivative work: Mouagip (talk)DNA_UV_mutation.gif: NASA/David HerringThis vector graphics image was created with Adobe Illustrator. – DNA_UV_mutation.gif (Public Domain) via Commons Wikimedia
