What is a Chromosomal Mutation? By definition, a chromosomal mutation is any change or error that occurs within the chromosome. Such errors can be attributed to any mistakes or problems that occur during cell processes like
mitosis and
meiosis .
Unlike gene mutations that involve the alteration of a gene or a segment of DNA in the chromosome, chromosomal mutations occur and change the entirety of the chromosome itself. Three types of chromosomal mutations exist namely, mutations on the structure of chromosomes , mutations on the chromosome number , and mutations on the sex chromosomes . This kind of chromosomal mutation usually occurs during any errors in cell division. This happens when homologous chromosomes
1. Deletion This type of mutation occurs when a part of the DNA is not duplicated
[2] or is lost during DNA replication. The size of this region can either be a mere
nucleotide or can be large as an entire chromosome.
Disorders Due To Deletion Common disorders due to deletion mutation in humans are: Cri du chat , Duchenne muscular dystrophy , Di George’s syndrome , and so on.
2. Duplication This type of mutation occurs when an extra copy of a region
[3] (or regions) in the DNA is produced. This duplicated region can either be located in its normal location in the chromosome or sometimes in other parts of the chromosome or even in another chromosome.
This duplication can now supply additional material that has the ability to evolve new functions. Disorders Due To Duplication A common disorder due to human duplication mutation is Charcot-Marie-Tooth disease type I.
3. inversion During inversion
[4] , a portion of the chromosome is reversed and gets inserted back into the chromosome. Two types of inversion exist:
pericentric and
paracentric .
Disorders Due To Inversion A common disorder due to inversion mutation in humans is Amniocentensis during pregnancy.
4. Translocation Translocation happens when a fragmented chromosome tends to join with a non-homologous chromosome. This newly-formed segment then detaches from the chromosome and moves to a new position on another chromosome.
Disorders Due To Translocation Common disorders due to human translocation mutation are XX male syndrome, Down syndrome, Infertility, and Cancer.
Chromosomal Number Mutations
1. Aneuploidy Aneuploidy
[5] is a type of mutation in the chromosome number wherein the ploidy (chromosome number) of the new individual is different from its wild type. This is typically a result of the
nondisjunction of chromosomes during mitosis or meiosis, hence producing offspring with either extra or lost chromosomes.
The naming of aneuploid conditions is generally based on the number of chromosomes added or deleted. For instance, a monosomic (2n -1) individual bears only one copy of a chromosome instead of having two. Other variations of aneuploidy are trisomic (2n+1), nullisomic (2n-2), and disomic (n+1).
2. Polyploidy Polyploidy
[6] is a type of mutation that occurs when an individual bears more than one haploid set of chromosomes. If the individual with polyploidy bears three sets of haploid chromosomes, the condition is said to be triploidy. In contrast, if it has four haploid sets, the condition is said to be tetraploidy.
Interestingly, polyploidy is a common phenomenon among plants salamanders frogs
The Advantages of Chromosomal Mutations Believe it or not, random errors occurring during cell division can benefit organisms. Listed below are some of them.
1. Survival Mutations are essential for populations because they help some individuals adapt to their environment while they maintain their survival. They are also an important force in
evolution because they balance out the frequency of alleles present in the population.
In humans, some successful mutations include malaria resistance, lactose tolerance, and atherosclerosis tolerance.
2. Diversity Mutations in the chromosomes are highly connected to the diversity (not only genetically but also physically) of living organisms. Ultimately, the close interactions between inherited mutations and environmental pressures generate diversity among species.
And clearly, some of the fundamental mechanisms of evolutionary change cannot (and continue to) operate without genetic diversity. Examples : As some chromosomal mutations are harmless, humans get different color eyes such as black, brown, grey, green, or blue.
The Disadvantages of Chromosomal Mutations Some mutations can be quite detrimental as well. The following are some of the most common disadvantages of mutations in the chromosomes:
1. Genetic Disorder Mutations in the chromosome can cause various genetic disorders. While most genetic disorders are rare, the severity of the error in even a small portion of the chromosome can be highly devastating.
2. Other Diseases Aside from inheritable disorder, certain mutations in the chromosomes can also bring about the onset of other diseases like cancer (i.e. lung, breast, and bladder.).
the only constant is change ” prove true?
Cite This Page
[1] – “What is a chromosome? – Genetics Home Reference” . Accessed March 29, 2017. Link .[2] – “Deletion Mutation: Definition, Examples & Diseases – Video & Lesson Transcript | Study.com” . Accessed March 29, 2017. Link .[3] – “Duplications – An Introduction to Genetic Analysis – NCBI Bookshelf” . Accessed March 29, 2017. Link .[4] – “Chromosome Mutation” . Accessed March 29, 2017. Link .[5] – “Aneuploidy – An Introduction to Genetic Analysis – NCBI Bookshelf” . Accessed March 29, 2017. Link .[6] – “Polyploidy | Learn Science at Scitable” . Accessed March 29, 2017. Link .
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