Two eukaryotic proteins have one domain in common but are otherwise very different. Which of the following processes is most likely to have contributed to this similarity? a. gene duplication b. alternative splicing c. exon shuffling d. random point mutations

Verified step by step guidance

1. Identify the key concept: The question is asking about the process that leads to two proteins having a common domain but differing significantly otherwise.
2. Understand the options: Gene duplication involves copying a whole gene, leading to two identical genes initially. Alternative splicing involves different mRNA molecules produced from the same pre-mRNA, affecting protein variety. Exon shuffling can mix different exons to create new combinations of domains in proteins. Random point mutations involve changes in single nucleotide bases, which generally affect protein structure subtly.
3. Analyze the impact of each process: Gene duplication and random point mutations do not typically result in proteins sharing only one domain. Alternative splicing could potentially lead to shared domains, but it's more about variations in the same gene rather than between different proteins.
4. Focus on exon shuffling: Exon shuffling allows for the mixing and matching of exons, which are protein-coding segments of genes. This process can create proteins that share common domains (from shared exons) but are otherwise different due to the inclusion of different exons.
5. Conclude the most likely process: Given that exon shuffling directly involves the recombination of protein-coding segments (exons), it is the most likely process to result in two proteins having one domain in common but being otherwise very different.

Key Concepts

Gene Duplication

Gene duplication is a process where a segment of DNA is copied, resulting in two identical or similar genes. This can lead to the evolution of new functions as one copy may retain the original function while the other can accumulate mutations and potentially develop a new role. In the context of the question, gene duplication could explain why two proteins share a common domain despite their overall differences.

Exon Shuffling

Exon shuffling is a molecular mechanism that allows for the rearrangement of exons, the coding regions of genes, during recombination. This process can create new combinations of functional domains within proteins, leading to diversity in protein structure and function. The presence of a common domain in two different proteins could be a result of exon shuffling, as it allows for the mixing of existing domains.

Alternative Splicing

Alternative splicing is a process by which a single gene can produce multiple protein isoforms by including or excluding certain exons during mRNA processing. This mechanism increases the diversity of proteins that can be generated from a single gene, allowing for functional variations. However, while alternative splicing can lead to similar proteins, it is less likely to explain the presence of a common domain in two otherwise different proteins compared to gene duplication or exon shuffling.