Question

Some evolutionary biologists argue that, overall, regulatory mutations are more likely to result in adaptation than changes in the protein coding sequence of genes. Considering the logic underlying their argument, in which case below would this expectation not apply to a particular gene involved in adaptation?

1) the gene is involved in multiple functions
2) the gene is involved in only one function
3) the gene is expressed in different tissues
4) the protein encoded by the gene performs an important function

Answer 1

The expectation that regulatory mutations are more likely to result in adaptation than coding sequence mutations does not apply when a gene is involved in only one function, as protein function alterations can be detrimental.

Step-by-step explanation:

Considering the logic underlying the argument that regulatory mutations are more likely to result in adaptation than changes in the protein-coding sequence of genes, expectation would not apply to a particular gene involved in adaptation in case the gene is involved in only one function. Genes that encode proteins with a single function are less likely to tolerate changes in their coding sequences without detrimental effects. Protein function is often crucial, and any alteration could be harmful rather than beneficial.

In contrast, genes involved in multiple functions, expressed in different tissues, or whose proteins perform multiple or redundant roles might better tolerate and potentially benefit from regulatory mutations, as these can fine-tune when, where, and how much protein is made, without altering the protein's function. Regulatory mutations in promoters or other regulatory elements can lead to adaptations by modifying gene expression patterns in a way that is beneficial to the organism. Additionally, such mutations could prevent a gene from being permanently off or on, which is essential for preserving cellular balance.