Which of the following mutations would be most likely to have a harmful effect on an organism? a. a deletion of three nucleotides near the middle of a gene b. a single nucleotide deletion in the middle of an intron c. a single nucleotide deletion near the end of the coding sequence d. a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Verified step by step guidance

1. Identify the type of mutations listed and understand their general impact on gene function. Deletions and insertions can disrupt the reading frame (frameshift mutations), while mutations in introns might not affect the protein if they do not alter splicing.
2. Analyze option a: A deletion of three nucleotides near the middle of a gene. This could remove an amino acid but may not cause a frameshift mutation, potentially having a less severe effect if the deleted amino acids are not critical for protein function.
3. Analyze option b: A single nucleotide deletion in the middle of an intron. Introns are non-coding regions and are spliced out during mRNA processing. This mutation is less likely to affect the protein unless it alters the splicing machinery.
4. Analyze option c: A single nucleotide deletion near the end of the coding sequence. This could cause a frameshift mutation altering the final part of the protein, potentially disrupting its function or stability.
5. Analyze option d: A single nucleotide insertion downstream of, and close to, the start of the coding sequence. This mutation is likely to cause a frameshift right from the start of the protein, altering the entire amino acid sequence and likely rendering the protein nonfunctional.