Final answer:
Promiscuous proteins can perform multiple functions and may catalyze reactions on different substrates, possibly leading to evolutionary adaptations. Gene recruitment involves a gene being co-opted for a new function, frequently due to mutations. These concepts are distinct in evolutionary biology.
Step-by-step explanation:
Promiscuous proteins and gene recruitment are distinct concepts in the context of evolutionary biology. Promiscuous proteins characteristically have the ability to perform more than one function due to their broad specificity, which could allow them to catalyze reactions on different substrates. Over time, one of these additional functions may become more prominent or beneficial to the organism, leading to evolutionary adaptations and specialization. On the other hand, gene recruitment refers to the process where a gene or network is co-opted for a different function, often as a result of a mutation or a change in gene regulatory sequences. This co-option can lead to the gene acquiring a new role within the organism, completely separate from its original function. It's a mechanism that contributes to the development of new biological functions and complexity.
As an example, consider a promiscuous enzyme that has the incidental ability to break down a toxin in addition to its primary metabolic role. Should the environment change and the toxin becomes more prevalent, this secondary function might become essential for survival, and natural selection could act to enhance this function through mutations that improve the enzyme's efficiency toward the toxin.
Conversely, gene recruitment might involve the co-option of a gene previously involved in a developmental process, which through mutations, becomes integral in a different developmental pathway or even in a new physiological function. To clarify the differences: Option 1 is incorrect because gene recruitment is not simply about utilizing different substrates; Option 2 is correct in describing gene recruitment; Option 3 inaccurately associates promiscuous proteins with the result of gene recruitment; Option 4 is incorrect, as 'a' is not accurate and does not pair with 'c'; and Option 5 is incorrect as promiscuous proteins and gene recruitment are not synonymous terms.