A genetic mutation is a change in a genomic sequence. They are the sudden and spontaneous changes in the cell. Most of the mutation has no effect on the organisms because of the large portion of the DNA. Only the small percentage of the mutation causes visible but non lethal changes in the phenotype. Genetic mutation can have various causes such as radiation, viruses, DNA replication, errors in meiosis and many more. A genetic mutation has a damaging effect for the body.
This is caused by several reasons; it can be by spontaneous 'or' induced. Spontaneous genetic mutation can be caused by the tautomerism (chemical reactions), 'or' deprivation (alternation of the DNA or the slipped strands misparing). The induced mutations can be caused by several chemicals such as hydroxylamine, base analogs, alkylating agents, and agents forming DNA, agents intercalating DNA, DNA cross linkers, oxidative damage, ultraviolet radiation, etc.
Genetic mutation is a serious problem and people who suffer from this usually have all sort of serious conditions and disease. A genetic mutation is an agent that can bring about a permanent alteration to be physical composition of a DNA gene such that a genetic message is changed. It occurs at a frequency of about one in every one billion pairs. Everybody has about 6 mutations in each cell in their body. Mutations are not always seen, they may be both beneficial and harmful. It is the source of genetic variations in a population increasing biodiversity.
How are mutations inherited?
They are inherited by the mutations in gametes (egg and sperms) are passed on to off-springs.
Mutations in the body cells only affect the organisms in which they occur and are not passed to the off springs.
TYPES OF GENETIC MUTATION
There are 3 types of genetic mutations. They are as follows:
Point Mutations
A point mutation is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide of the genetic material, DNA 'or' RNA. Point mutation occurs when the base sequence of a codon is changed, for eg: GCA is changed to GAA. Sickle cell disease is the result of one nucleotide substitution which occurs in hemoglobin gene. There are three types of point mutations:
• Substitution point mutations.
• Deletion point mutations.
• Insertion point mutations.
Deletion point mutations and Insertion point mutations are also called as a Frame shift mutations
Substitution Point Mutations
It is a type of mutation in which a single nucleotide 'or' nitrogen base is substituted for another different nucleotide 'or' nitrogen base in a codon. It may or may not affect the amino acid or the protein.
Normal DNA: CGA-TGC-ATC Alanine – Threonine – stops
Mutated DNA: CGA-TGC-TTC Alanine – Threonine – Lysine
Deletion Point Mutations
It is a type of mutation in which the nitrogen base is deleted or removed from the sequences. It causes the triplet "frames to shift". It always affects the amino acids and consequently the protein.
Normal DNA: CGA-TGC-ATC Alanine – Threonine – stops
Mutated DNA: CGA-TGC-TC Alanine – Serine
Insertion point mutations
It is a type of mutation in which a nitrogen base is inserted or added to the sequences. It causes the triplet "frames to shift". It always affects the amino acids and consequently the protein.
Normal DNA: CGA-TGC-ATC Alanine – Threonine – stops
Mutated DNA: CGA-TAG-CAT-C Alanine – Leucine -Valine
Mutations are caused by Radiation and certain chemical compounds which are known as "mutagens". Gene mutations are the permanent alterations in the ALLELE [Allele – any of the variations of a GENE that may occupy the same position (locus) on a CHROMOSOME]. Pairings on the gene or on the chromosomes' that pass on to the new cell and ultimately to the offspring's. Genetic mutation is a serious problem and people who suffer from this usually have all sort of serious conditions and disease for.eg. Cancer is caused by somatic mutations. Testing for mutagenicity by the "Ames test" is a key step is development of pharmaceutical drugs.