Answer: A reading frame shift mutation involves the insertion or deletion of a certain number of nucleotides that is not divisible by three, because the cell reads a gene in groups of three bases (a codon). This type of mutation can change the reading frame causing a different translation from the original, because it will code for different amino acids.
Explanation:
DNA is the double-stranded molecule composed of nucleotides which are the functional unit of nucleic acids and are composed of a base (which can be Adenine, Thymine, Guanine, Cytosine, and Uracil replacing Thymine in RNA), a phosphate group and a sugar which can be ribose in RNA and deoxyribose in DNA. The reading frame is one of the possible ways in which a sequence of DNA or RNA nucleotides can be divided to form a group of codons that are consecutive and non-overlapping. A codon consists of a set of three nucleotides and each codon codes for an amino acid during translation or protein synthesis. When DNA is transcribed into messenger RNA (mRNA), this mRNA is read on ribosomes during translation and the three bases of each codon will code for an amino acid.
A single-stranded nucleic acid (RNA) molecule has a phosphate end, called the 5' end (read five prime end) and a hydroxyl end, called the 3' end. These ends define the 5'-3' direction. There are three possible reading frames in which a nucleotide sequence can be read in the 5'-3' direction. Each of these reading frames could start at a different nucleotide of the same codon. In a double-stranded nucleic acid (DNA), there are also three additional reading frames corresponding to the complementary strand, but in an antiparallel direction. Since the two strands of a double-stranded nucleic acid are antiparallel, the 5'-3' direction of the second strand corresponds to the 3'-5' direction of the first strand.
Generally, there is at most, a single biologically relevant reading frame for a given section of a nucleic acid, and that reading begins when a start codon indicating the initiation of protein synthesis is found in the messenger RNA. And the process stops when a stop codon is reached.
An insertion is a type of mutation that involves the addition of genetic material. It can be small and involve a single DNA base pair, or large and involve a fragment of a chromosome. A deletion is a type of genetic mutation in which genetic material is lost, from a single DNA nucleotide pair to an entire chromosome fragment. A reading frame shift mutation involves the insertion or deletion of a certain number of nucleotides that is not divisible by three, because the cell reads a gene in groups of three bases, as it was explained before. This type of mutation can change the reading frame causing a different translation from the original.
