Skin color is often one of the first traits people notice in each other. Studies in zebrafish uncovered a mutation that altered a transport protein and resulted in light-colored fish. This discovery led to the finding that the same gene in humans has a strong influence on skin pigmentation in many populations. The zebrafish mutation that reduced coloration created a null allele of the transport protein gene. Which of the following types of mutation would be most likely to create this null allele?a. a missense mutationb. a frameshift mutationc. a neutral mutationd. a silent mutation

Verified step by step guidance

1. Identify the type of mutation that would most likely result in a null allele. A null allele typically results in a nonfunctional protein due to the gene mutation.
2. Understand the different types of mutations listed: missense mutation (changes one amino acid in the protein), frameshift mutation (insertion or deletion of nucleotides that shifts the reading frame), neutral mutation (does not affect protein function), and silent mutation (does not change the amino acid sequence).
3. Analyze which mutation could lead to a complete loss of function in the protein. Frameshift mutations often result in a completely different and nonfunctional protein because they change the way the codons are read, which usually alters the entire amino acid sequence downstream of the mutation.
4. Compare the impact of the other mutations: Missense might only change one amino acid and might not completely disrupt protein function; neutral and silent mutations do not affect the protein function at all.
5. Conclude that the mutation type that is most likely to create a null allele, which results in a nonfunctional protein, is the frameshift mutation.

Key Concepts

Types of Mutations

Mutations are changes in the DNA sequence that can affect gene function. The main types include missense mutations, which change one amino acid in a protein; frameshift mutations, which alter the reading frame of the gene; silent mutations, which do not change the amino acid sequence; and neutral mutations, which have no significant effect on fitness. Understanding these types is crucial for determining how they impact protein function and phenotypic traits.

Null Alleles

A null allele is a variant of a gene that results in a complete loss of function of the gene product, often due to mutations that disrupt protein synthesis. This can occur through various mechanisms, such as frameshift mutations or premature stop codons. In the context of the zebrafish study, the null allele of the transport protein gene led to reduced pigmentation, illustrating how genetic changes can directly influence observable traits.

Frameshift Mutations

Frameshift mutations occur when nucleotides are inserted or deleted from the DNA sequence, causing a shift in the reading frame during translation. This often results in a completely different and usually nonfunctional protein due to altered amino acid sequences and the potential introduction of premature stop codons. Given their disruptive nature, frameshift mutations are likely candidates for creating null alleles, as seen in the zebrafish example.