Genetics;Mutations induction mechanisms
A genetic mutation can sometimes be called punctual mutation because within a gene one of its alleles changes to a different allele. The punctual mutation refers to the alterations of DNA bases either individual or a small group of base pairs.
According to the structure and sequence of a gene, the shapes in mutations could change a wild type gene. Mutations that eliminate or decrease gene function are the most common.
There are two types of specific mutational changes in DNA:
- Base substitutions: These are the mutations in which one pair of bases is replaced by another torque.
- Bases or delection: They are nucleotide pairs. The simplest of these mutations is the addition of simple base pairs.
Hot points
When observing a set of mutations induced by different mutagens, there is a different specificity that is characteristic of each mutagen, this specificity is a product of the preference of a mutagen given for some type of mutation or for some mutational sites called hot points. Hot points are genes where the mutation is carried out more frequently.
Mutagen Action
Mutans act through at least three different mechanisms: they alter, replace or damage. In the DNA they replace a base, they alter a base for them to match another or damage a base so that the pairing is not possible.
Base replacement
As mentioned above, the substitution of bases are the mutations in which a pair of bases is replaced by another torque, this substitution is divided into two;transitions and transversions. The transition is when one base is replaced by another of the same chemical condition, while the transversion is when a base of the same chemical condition is replaced by one base of another condition.
Base analogues are chemical compounds that are similar to the normal nitrogen bases of DNA that are often gathered to DNA instead of normal bases. Many analogues have pairing properties and can produce mutations when they cause the insertion of nucleotides that are not correct in replication.
Base modification
A base is altered when some mutagens are not integrated into DNA, causing evil pairing.
Alkylating agents can modify the bases of incoming nucleotides in DNA synthesis. Intercalators are also DNA modifiers, this compound has proflavin, acridine orange and ICR compounds. These agents are flat molecules that mimic base pairs and can be interspersed between the nitrogen kisses stacked in the nucleus of the double DNA propeller.
Bases lesions
You cannot carry out a pairing when many mutans damage one or more bases. This generates a replication block because DNA synthesis does not continue beyond a base that does not specify your complementary partner through hydrogen bonds. Mutagenos who damage places in the pairing of bases depend on the SOS system.
SOS system
SOS system is induced as an emergency reaction so that cell death does not occur when there is damage to DNA. This system causes the cell to exchange the dead cell for a mutagenesis level.
Different SOS dependent mutans have very different specificities. Mutations must occur in response to specifically damaged bases.
Spontaneous mutation mechanisms
Spontaneous mutations are very rare mutations, they can occur due to errors in DNA replication, spontaneous lesions and transpononable genetic elements.
Errors in DNA replication
Errors in DNA replication can cause picture displacement mutations.
The Streissinger model announces that the frequency of a table displacement depends on the amount of base pairs formed in the evil pairing of repeated sequences.
Deletions are the cause of the rupture of a chromosome with loss of genetic material, they produce an abnormal phenotype due to the loss of genes. Deletions with several base pairs constitute a fraction of spontaneous mutations
Spontaneous lesions
Spontaneous lesions also cause mutations, the most frequent are purification and discouragement.
DEPURINATIONS
Training occurs spontaneously and is a consequence of the loss of a nucleotide purine base resulting in an apurine site. During the replication, the apurine sites do not specify any base, but in some cases a base can be inserted in that site and that sometimes generates a mutation.
DESANIMATION OF THE C
DISANIMINATION IS THAT SPANNIOUS ALTERATION THAT AN AMINO GROUP OF A BASE, THE CYNOSINE GENERA URACILO. The non -repaired Us.
Damaged bases oxidatively
This type of injury is involved in mutagenesis. Active oxygen species such as superoxide, hydroxyl and hydrogen peroxide radical.
Bibliographies
- Griffiths, a., Gelbart, w., Lewontin, r. and Miller, J. (1999). Modern Genetic Analysis. 7th ed. [Book] New York: W. H. Freeman and Company. All Rights Reserved., p.Chap. 7. Retrieved from: file: /// c:/users/hp/appdata/local/temp/rar $ exa0.091/MODERN%20GENETIC%20ANALYSIS/WWW.NCBI.NLM.nih.GOV/Books/[Email Protected]= BV.View..showsection & rid = mga.Section.D1E15890.HTM [accessed March 2, 2020].
- Dr. Horwitz, m. (2005) Clinical Cytogenetics 3.Part. [Online] Biomodel.Uah.it is. Biomodel. Recovered from: http: // biomodel.Uah.is/cytogene/hornwitz/cygogen3.HTM [accessed March 2, 2020].
- Contreras, r. (2012). The origin of the specific genetic mutations |The Biology Guide. [Online] Biology.Laguia2000.com. Recovered Det: https: // biology.Laguia2000.com/genetica/el-Origen-de-Llas-Mutaciones-Puntual-genetica [accessed March 02. 2020].
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