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Chromosome Mutations Definition
Following fertilization, both parents’ genetic information is anticipated to be visible in the baby. However, this genetic material can mutate, which might result in deadly or unfavorable effects in the new organism’s conclusion in most situations. This course examines genetic mutations and their effects on the new organism’s result. This course will go through the many forms of chromosomal mutations.
Chromosome Mutations and Non-disjunction
Non-disjunction is a well-known example of a mutation. Non-disjunction occurs when the spindle fibres during meiosis fail to split, resulting in gametes with one additional chromosome and gametes without a chromosome.
Down’s syndrome develops when this non-disjunction occurs in chromosome 21 of a human egg cell. This is due to the fact that their cells have 47 chromosomes, as opposed to the typical complement of 46 in humans. A chromosome’s essential structure is susceptible to mutation, which will most likely occur during meiosis crossing over.
As shown above, there are a variety of ways in which the chromosomal structure might alter, all of which will have a negative impact on the organism’s genotype and phenotype. However, if the chromosomal mutation damages an important portion of DNA, the baby may be aborted before it has a chance to be born.
Chromosome Mutations Examples
The following are examples of chromosomal mutations in which whole genes are relocated:
i. Deletion
As the name indicates, when a chromosome’s genes become detached to the centromere, they are permanently lost.
- Prior to the mutation, the chromosome was normal.
- Genes that are not linked to the centromere fall free and are lost indefinitely.
- Some genes on the new chromosome are missing, which might be deadly depending on how crucial these genes are.
ii. Duplication
Due to gene duplication, the mutant genes are shown twice on the same chromosome in this mutation. This mutation has the potential to be beneficial because no genetic information is lost or changed, and new genes are acquired.
- Prior to the mutation, the chromosome was normal.
- Genes are copied and put into the genetic sequence from the homologous chromosome.
- A new chromosome has all of its original genes, as well as a duplicated gene that is typically innocuous.
iii. Inversion
This happens when the order of a group of genes is reversed, as seen in the diagram below.
- Unaltered chromosome
- Genetic connections are broken, and the sequence of these genes is reversed.
- Depending on which genes are reversed, the new sequence may not be viable for producing a creature. It’s also possible that this mutation will result in beneficial traits.
iv. Translocation
When information from one of two homologous chromosomes breaks and binds to the other, this is called a break. This type of mutation is usually catastrophic.
- A pair of homologous chromosomes that has not been changed.
- Gene translocation has resulted in the attachment of certain genes from one chromosome to the opposite chromosome.
Nucleotide Citations
- Imprinting mutations on human chromosome 15. Hum Mutat . 1997;10(5):329-37.
- Chromosome 12 alterations and c-Ki-ras mutations in colorectal tumors. Cancer Genet Cytogenet . 1993 Sep;69(2):161-2.
- Mutations arising during repair of chromosome breaks. Annu Rev Genet . 2012;46:455-73.
- Figures are created with BioRender.com
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