Sequence Of Dna Mutation

HOW DNA CAN BE MUTATED AND WHAT ARE THE SYSTEMS THAT CAN REPAIR BACK THE MUTATED DNA

DNA mutation. Mutation are permanent heritable alteration in the base of sequence of DNA. Mutation occurs either because of spontaneous errors in DNA replication or in a meiotic recombination of as a consequence of the damaging effects of physical or chemical agents on the DNA.There are few concept in order to understanding mutation in DNA. It is known that DNA is a chemical compounds which the components are in an unique structures. The DNA molecules however can be modified, resulting in mutation. One path for the DNA to be mutated is by transition or by transversion. In transition, purine will be changed to another purine nucleotide, which is (A→G) and

As their name suggest, insertion means that an area of a chromosome, for example from chromosome 4 is inserted to chromosome 20, resulting mutation to both chromosome. Deletion is also straightforward. Part of the chromosome was deleted, resulting changes of the gene sequence and that makes the mutation happens. Insertion and deletion will change the sequence of triplets. In this case, insertion or subtracting 3nt will leave the triplet intact, providing evidence that a codon has 3nt.

A point mutation of also called substitution, is a type of mutation that cause the replacement of a single base nucleotide with another nucleotide. Often the term point mutation is also includes insertion or deletion of a single base pair. This causes the mutation have more adverse effect since the synthesized protein no longer being written in triplets, but in different orders. This type of mutation is called frameshift mutation.

Mutation also can be classed as either induced or spontaneous. Spontaneous mutation on the molecular levels includes tautomerism, depurination, deamination, transition and transversion. For induced, mutagen that cause the changes are chemical mutagen and radiation mutagen. Both effect the DNA on the molecular level by changing the molecular structure. This kind of mutation can be classed into two, which is endogenous damage (caused by reactive oxygen species-oxidative deamination) or exogenous damage (toxic compounds,

DNA also can directly repaired damaged bases. A repair enzyme recognizes incorrect structure in the DNA and directly converts it to a correct structure.

Base exision repair involves a category of enzymes known as DNA-N-glycosylacases. The enzymes identify the damaged base and cleave the bond between it and the sugar in the DNA. Then it will remove one base, excises several around it and then replaces it with several new bases using DNA polymerase adding to 3’ ends and then closing it with ligase attached to 5’ end. Another type of DNA repair is nucleotide excision repair. (NER). NER will nicks DNA around damaged base and removes the region. Then it will fills it with Pol on 3’ends and attached 5’ end with