Frameshift Mutation vs Point Mutation
The main two ways of gene mutations are the frameshift and point mutations. Firstly, a mutation is an alteration in the genetic material in general. These changes can take place in different ways and magnitudes. Gene mutations are simply the changes occurring in the nucleotide sequence of a particular gene of an organism. Both frameshift and point mutations are such alterations in the nucleotide sequence of a gene. However, the two types vary from each other in many ways, despite the result is a changed gene; hence, a different phenotype could be expressed eventually.
As its name hints, the frame of the nucleic acid is shifted when frameshift mutations take place in a gene. Firstly, it would be appropriate to know that there are two types of frameshift mutations known as insertions and deletions. All these take place when the DNA strand is dismantled during DNA replication or protein synthesis. When the DNA strand is unwound during protein synthesis, the mRNA strand is formed, and the DNA strand is reformed as per the present nucleotide sequence. However, a new nucleotide could be added into the present sequence at any vulnerable place. Therefore, the new DNA strand will have an additional nucleotide. Additionally, this process could take place during DNA replication after unwinding and before winding with the new strand. Since a nucleotide has been added to the original sequence, the DNA strand has undergone a change called mutation, and this particular type is known as an insertion. Similarly, a deletion could take place if a nucleotide has been missed during reforming the DNA strand after being dismantled. Both deletions and insertions cause the frame of the DNA strand to shift one way or the other. These types of mutations are also known as framing errors as the frame has been erred. It is important to notice that the number of nucleotides is changed in the DNA strand when a framing error is taken place.
Point mutation is a change taken place in a particular gene at a particular place. An exchange of nucleotides takes place as purine base with the corresponding purine base or pyrimidine base with the corresponding pyrimidine base. Hence, Adenine could be replaced with Thymine, or around the other way. Additionally, Guanine could be replaced with Cytosine, or around the other way. This type of exchanges is termed as the transition point mutation.
However, when a purine base is exchanged with a pyrimidine base, the mutation is known as the transversion. These mutations may or may not result in changing the synthesized protein. When a mutation has caused a change in the synthesized protein, it is termed as a missense mutation, whereas the unexpressed mutations are called as silent mutations. In addition, some point mutations are capable of causing a terminator codon, where a stopping signal will be passed as a codon sequence and the protein synthesis will be stopped with a shortened protein molecule. This type of point mutation is termed as a nonsense mutation. As it seems, point mutations are of few types, but the result is always a change in a single nucleotide. The number of the nucleotides is not changed, but the structure will be different; hence, the function of the gene may be altered.
What is the difference between Frameshift Mutation and Point Mutation?
• The frame of the DNA strand is shifted one way or the other in a frameshift mutation, whereas point mutations do not change the frame of the DNA strand.
• The gene structure and the number of nucleotides are changed in frameshift mutations while point mutations cause only the structure of a gene.
• Frameshift mutations are of two types, but point mutations are of few types.