What happens if an incorrect nucleotide is not removed

Insertions, deletions, and duplications can all be frameshift variants. Some regions of DNA contain short sequences of nucleotides that are repeated a number of times in a row. For example, a trinucleotide repeat is made up of sequences of three nucleotides, and a tetranucleotide repeat is made up of sequences of four nucleotides. A repeat expansion is a variant that increases the number of times that the short DNA sequence is repeated.

This type of variant can cause the resulting protein to function improperly. Other chapters in Help Me Understand Genetics. Genetics Home Reference has merged with MedlinePlus. Learn more. The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health. What kinds of gene variants are possible? From Genetics Home Reference. Variant types include the following: Substitution This type of variant replaces one DNA building block nucleotide with another.

Missense : A missense variant is a type of substitution in which the nucleotide change results in the replacement of one protein building block amino acid with another in the protein made from the gene. The amino acid change may alter the function of the protein.

Nonsense : A nonsense variant is another type of substitution. Instead of causing a change in one amino acid, however, the altered DNA sequence results in a stop signal that prematurely signals the cell to stop building a protein.

This type of variant results in a shortened protein that may function improperly, be nonfunctional, or get broken down. Insertion An insertion changes the DNA sequence by adding one or more nucleotides to the gene. A frameshift mutation is a genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read.

A DNA sequence is a chain of many smaller molecules called nucleotides. DNA or RNA nucleotide sequences are read three nucleotides at a time in units called codons, and each codon corresponds to a specific amino acid or stop signal. During translation, the sequence of codons is read in order from the nucleotide sequence to synthesize a chain of amino acids and form a protein. Frameshift mutations arise when the normal sequence of codons is disrupted by the insertion or deletion of one or more nucleotides, provided that the number of nucleotides added or removed is not a multiple of three.

Very often, what we see is a premature termination. Instead of the encoded protein being of a certain particular size, it'll end up being much shorter, and it won't be able to accomplish the role that's been set out for it. Elaine A. Ostrander, Ph. Featured Content.