Frameshift

A frameshift or frameshift or frameshift is a particular type of mutation . It is a shift in the reading frame of genes on DNA . The genetic information on DNA is organized in the form of base triplets or codons , with three bases coding for one amino acid . If a number of bases that is not a multiple of three is lost ( deletion ) or is added as part of a mutation from a gene sequence (Insertion ), the reading frame of the base triplets following the mutation changes. As a result, all base triplets from the mutation site on have an altered sequence. This u. Other amino acids may be encoded or the translation may be terminated prematurely , since the mutation can result in a stop codon . Although the direct change may only affect a single base, the effects can be significant. Frame shifts are caused , among other things, by intercalating substances .

Deletion

Original base sequence:

… GCC AAT AGT GCT CTA ACG …

Deletion of a base: A(first base in the third codon)

… GCC AAT GTG CTC TAA CG …

Insertion

Original base sequence:

… GCC AAT AGT GCT CTA ACG …

Insertion of a base: T(first base in the second codon)

… GCC TAA TAG TGC TCT AAC G …

Clear illustration

The following sentence is an illustrative example to illustrate the effect of mutations on the reading frame:

description	sentence	Reading frame
Original text	`DIE KUH LAG AUF DEM HEU UND TAT NIX`
Exchange of a letter	`DIE KUH LAG RUF DEM HEU UND TAT NIX`	remains
Insert a letter	`DIE KUH LAG MAU FDE MHE UUN DTA TNI X`	shift
Insert two letters	`DIE KUH LAG MIA UFD EMH EUU NDT ATN IX`	shift
Insert three letters	`DIE KUH LAG MIT AUF DEM HEU UND TAT NIX`	remains
Remove a letter	`DIE KUH LAG UFD EMH EUU NDT ATN IX`	shift
Removing two letters	`DIE KUH LAG FDE MHE UUN DTA TNI X`	shift
Removing three letters	`DIE KUH LAG DEM HEU UND TAT NIX`	remains

literature

Jochen Graw: Genetics . 4th, completely revised Edition. Springer, Berlin / Heidelberg 2006, ISBN 3-540-24096-9 , Chapter 10: Changes in the genome: mutations .