Mutations present permanent and heritable changes in the genome. We distinguish gene and chromosome mutations. Mutations in the level of genes are called point mutations because only one to several nucleotides are changed. These processes are known as deletion, insertion, and substitution. Deletion presents a loss of nucleotides which changes DNA sequence. When new nucleotides are embedded in the DNA chain, it is known as insertion. Substitution implies the process where new nucleotides are inserted while the ones that were present in that specific spot in a DNA molecule are deleted.
Mutations can also appear in chromosomes altering their number and structure. There are four types of mutations – deletion, duplication, inversion, and translocation. In deletion, a whole or one part of a chromosome is lost. Duplication presents an extra copy of a whole or one part of a chromosome. In an inversion, parts of a chromosome change order, while in translocation a part of one chromosome detaches and then connects to another.

Mutations present permanent and heritable changes in the genome. However, not all mutations alter an organism’s phenotype. Some mutations occur in a non-functional part of a DNA or they change the codon, but not the amino acid that corresponded to the original codon. Some mutations can cause small changes in the appearance of an organism, while others cause large changes, both harmful and helpful.

If the effect of a mutation is not visible, it tells us that an organism’s phenotype isn’t altered. The cause lies in the fact that some mutations occur in a non-functional part of a DNA or they change the codon, but not the amino acid that corresponded to the original codon. Therefore, the only way for a scientist to know if a mutation occurred is to read a genetic code and search for a mutation.

Mutations in the level of genes are called point mutations because only one to several nucleotides are changed. These processes are known as deletion, insertion, and substitution. Deletion presents a loss of nucleotides which changes DNA sequence. When new nucleotides are embedded in the DNA chain, it is known as insertion. In both of these cases, a whole sequence of nucleotides from the mutation point is displaced because amino acids that build a protein are determined by codons, which are made by three nucleotides in a row. Substitution implies the process where new nucleotides are inserted while the ones that were present in that specific spot in a DNA molecule are deleted. In this case, only one amino acid can be changed. However, since more than one codon determines the same amino acid, this alteration doesn’t have to result in a change of polypeptide structure.

Effect of mutations can be neutral, harmful, and beneficial to an organism. Neutral effects are consequences of the gene rather than chromosome mutations. Chromosome aberration usually alters the phenotype of an organism, therefore its effect isn’t neutral. There are three possibilities for a gene mutation that will not change the phenotype:
1. Base substitution in a segment of a DNK molecule that is inactive
2. Base substitution in an expressed gene that changes the codon but not the amino acid
3. Base substitution in an expressed gene that changes the codon as well as the amino acid, but that has little or no effect on the function of the final protein. If the mutation occurs in the active site of a protein, there is a high possibility that the effect will be harmful or beneficial. However, if the mutation happens in the other segments the effect may be neutral.

In order to produce different proteins, mutations must occur in the genetic material of a cell. We distinguish gene and chromosome mutations. Mutations in the level of genes are called point mutations because only one to several nucleotides are changed. These processes are known as deletion, insertion, and substitution.
Mutations can also appear in chromosomes altering their number and structure. There are four types of mutations – deletion, duplication, inversion, and translocation.