What is an in-frame mutation?
In-frame mutations occur when the number of deleted or inserted base pairs IS a multiple of three. This results in a change in only a few amino acids; it may still be possible for the protein to function, even though its sequence may be slightly different.
What is an in-frame insertion?
In-frame insertions occur when the reading frame is not altered as a result of the insertion; the number of inserted nucleotides is divisible by three. The reading frame remains intact after the insertion and translation will most likely run to completion if the inserted nucleotides do not code for a stop codon.
What does an insertion mutation do?
An insertion mutation occurs when an extra nucleotide is added to the DNA strand during replication. This can happen when the replicating strand “slips,” or wrinkles, which allows the extra nucleotide to be incorporated (Figure 2). Strand slippage can also lead to deletion mutations.
What is the difference between an insertion and a frameshift mutation?
The earlier in the sequence the deletion or insertion occurs, the more altered the protein. A frameshift mutation is not the same as a single-nucleotide polymorphism in which a nucleotide is replaced, rather than inserted or deleted.
Why are frameshift mutations so bad?
Frameshift mutations are among the most deleterious changes to the coding sequence of a protein. They are extremely likely to lead to large-scale changes to polypeptide length and chemical composition, resulting in a non-functional protein that often disrupts the biochemical processes of a cell.
What can cause a frameshift mutation?
A frameshift mutation is a mutation caused by an insertion or deletion, which causes a shift in the translational reading frame. Frameshift mutations have a more dramatic effect on the polypeptide than missense or nonsense mutations.
What occurs during frameshift mutation?
A frameshift mutation occurs when nucleotides are inserted into or deleted from the DNA and cause a “shift” in the reading of mRNA codons. Explanation: Frameshift mutations are insertions or deletions of nucleotides in DNA that change the reading frame (the grouping of codons).
What are the four types of mutations?
Four classes of mutations are (1) spontaneous mutations (molecular decay), (2) mutations due to error-prone replication bypass of naturally occurring DNA damage (also called error-prone translesion synthesis), (3) errors introduced during DNA repair, and (4) induced mutations caused by mutagens.