1. Substitution: This is the most common type of mutation where one nucleotide (A, T, C, or G) is replaced by another.
* Silent mutation: The substitution does not change the amino acid sequence of the protein encoded by the gene, because the genetic code is redundant.
* Missense mutation: The substitution results in a different amino acid being incorporated into the protein. This can have a range of effects, from no noticeable effect to a complete loss of protein function.
* Nonsense mutation: The substitution creates a stop codon, prematurely terminating translation and producing a truncated, often non-functional protein.
2. Insertion: One or more nucleotides are added to the DNA sequence. This can shift the reading frame of the gene, leading to a frameshift mutation.
3. Deletion: One or more nucleotides are removed from the DNA sequence. This can also cause a frameshift mutation.
4. Duplication: A segment of DNA is copied and inserted into the gene. This can lead to an increase in the amount of protein produced.
5. Inversion: A segment of DNA is flipped and reinserted into the gene. This can alter the order of genes and may disrupt gene function.
Consequences of mutations:
* No effect: Some mutations are silent and do not have any noticeable effect on the organism.
* Beneficial: Some mutations can be beneficial, providing a survival advantage.
* Harmful: Some mutations can be harmful, leading to diseases or disorders.
How mutations occur:
Mutations can occur spontaneously during DNA replication, or they can be induced by environmental factors such as radiation, chemicals, or viruses.
In summary, mutations are changes in the DNA sequence that can alter the structure and function of a gene. These changes can have a wide range of effects, from no noticeable effect to serious disease.
