A Level Biology Practice Exam

What does ab initio protein modeling rely on?

1. Random sequence generation for predictions

2. Empirical data from existing protein structures

3. The physical and electrical properties of amino acids

4. Functional annotations from genomic sequences

The correct answer is: The physical and electrical properties of amino acids

Ab initio protein modeling primarily relies on the physical and electrical properties of amino acids to predict the three-dimensional structures of proteins. This method is grounded in the understanding of how the properties of amino acids influence the folding and interactions that ultimately determine a protein's conformation. By using principles of chemistry and physics, such as the nature of polar and nonpolar interactions, electrostatic forces, and sterics, ab initio modeling can create simulations of protein folding pathways starting from the amino acid sequence alone, without relying on previously known structures. In contrast, random sequence generation for predictions would not systematically account for these properties, while empirical data from existing protein structures and functional annotations from genomic sequences are typically associated with comparative modeling approaches rather than ab initio methods. Thus, the correct choice highlights the fundamental scientific basis that drives the predictions of protein structures in ab initio modeling.