Gene Mutation

Gene mutation is also called point mutations. These mutations occur because of changes in the DNA base sequence or it can be said as nucleotide changes in DNA. A body synthesized proteins derived from readings of three base pairs (triplets). Each triplet codon carried a sense of the DNA chain. Triplet is a reading that is understandable by the body to produce amino acids. Gene mutations can be divided into two, namely the replacement of base pairs, insertion, and deletion of base pairs (Campbell, 1998: 318).

a. Replacement Pair of Bases

Replacement of base pairs is the substitution of one nucleotide with another nucleotide.Replacement of this base to create a mutant organism. In general, harmful mutations organism that undergoes them.

In Picture 1, a base A (purine base) replaces the base G (purine base) in the fourth codon of the mRNA. Replacement of this base to give effect to the organism or not at all. This, depending on how the replacement base is translated. For example, if the mutation causes the codon on the mRNA sequence of bases changed from GAA to GAG. Replacement of the base sequence, does not cause changes in the protein because the base sequence GAA and GAG is the same code for amino acid glutamate.

In another example, the replacement of base pairs may cause changes in the protein so that the protein is not working. This is shown in Picture 2. A replacement base by base U, can cause triplet code for amino new bases, namely valine. Examples of these are the cause of the disease sickle-cell anemia.

Normal hemoglobin DNA                                                         Mutated hemoglobin DNA

b. Insertion and deletion Couple Bases

Insertion and deletion is the addition (insertion) or reduction (deletion) of one or more base pairs in the gene. In general, mutations can cause harmful effects on the organism.Insertions or deletions of base pairs can cause a different reading of the triplet code of mRNA translation process. These mutations also called frame shift mutations (frameshift mutation). In Picture 3 , deletion of bases in DNA sequence U UUU cause a shift in the other bases that code for proteins that would occur (UUG). As if the insertions or deletions take place near the end of the gene, will produce
proteins are not working or damaged.

2 thoughts on “Gene Mutation

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