Question

Why are frameshift mutations likely to be more detrimental than point mutations, in which a single pyrimidine or purine has been substituted?

Short answer

Short Answer: Frameshift mutations are more likely to be detrimental compared to point mutations because they result in an entirely new amino acid sequence and often introduce premature stop codons, which can lead to non-functional or harmful proteins, disrupting normal cellular processes. In contrast, point mutations can sometimes be silent or have minimal effects on protein function, making their overall impact less severe than frameshift mutations.

Step-by-step solution

Define frameshift mutations and point mutations

Frameshift mutations occur when there is an insertion or deletion of one or more nucleotides in the DNA sequence, which leads to a shift in the reading frame. This can cause the resulting protein to have a completely different amino acid sequence, potentially rendering it non-functional or harmful. Point mutations are changes in a single nucleotide in the DNA sequence. This type of mutation can be further classified into: base substitutions, where one nucleotide is replaced by another nucleotide, or base insertions/deletions. These mutations can be of three types: silent mutations, missense mutations, and nonsense mutations. Silent mutations do not result in any change in the amino acid sequence of the protein, missense mutations change one amino acid to another, and nonsense mutations introduce a premature stop codon, causing the protein to be truncated.

Compare the effects of frameshift mutations and point mutations on protein synthesis

Now, let's analyze how these types of mutations affect protein synthesis: 1. Frameshift mutations usually lead to an entirely new sequence of codons following the mutation, which would cause the resulting protein to have a completely different amino acid sequence and potentially lose its function. Moreover, frameshift mutations may also introduce premature stop codons, resulting in a truncated, non-functional protein. 2. Point mutations may have varying effects on protein synthesis. If the point mutation is a silent mutation, there will be no changes in the amino acid sequence, and the protein remains functional. In the case of missense mutations, the altered amino acid can, in some cases, be tolerated, and the protein function may not be affected significantly. However, in other cases, the altered amino acid may cause a change in protein structure and function. Nonsense mutations, like frameshift mutations, introduce premature stop codons and lead to truncated proteins.

Explain why frameshift mutations are more likely to be detrimental

Since frameshift mutations result in an entirely new amino acid sequence and often introduce premature stop codons, they are highly likely to lead to non-functional or harmful proteins. This can disrupt normal cellular processes and potentially lead to serious diseases or genetic disorders. In contrast, point mutations can be silent, have minimal effect on protein function, or lead to truncated proteins, depending on the type. Thus, the overall impact of point mutations on cellular processes is generally less severe than that of frameshift mutations. In conclusion, frameshift mutations are likely to be more detrimental than point mutations due to their more extensive and disruptive effects on protein synthesis.