Which description correctly explains how a change in the DNA base sequence can affect the protein's three-dimensional structure?

Which description correctly explains how a change in the DNA base sequence can affect the protein's three-dimensional structure?

• A. Only affects non-coding regions.
• B. Cannot affect protein shape.
• C. Always stops translation.
• D. Changes the amino acid sequence, altering the primary and thus 3D structure.

Answer: (D)

The key idea is that the DNA base sequence determines the amino acid sequence of a protein, and the order of those amino acids dictates how the protein folds into its three-dimensional shape. A change in the DNA bases can alter a codon, which may change the encoded amino acid(s). When the amino acid sequence is altered, the protein’s primary structure changes, and that disrupts the way the chain folds. The specific side chains interact differently, affecting hydrophobic cores, hydrogen bonds, ionic interactions, and disulfide bonds, so the final three-dimensional structure can be different. This is why mutations that modify the amino acid sequence can change the protein’s shape and often its function. Some mutations don’t change the amino acid (silent) and may not affect structure, or can cause larger disruptions like frameshifts or nonsense mutations, but the fundamental connection is that altering the amino acid sequence changes the primary structure and thus the 3D structure.

The key idea is that the DNA base sequence determines the amino acid sequence of a protein, and the order of those amino acids dictates how the protein folds into its three-dimensional shape. A change in the DNA bases can alter a codon, which may change the encoded amino acid(s). When the amino acid sequence is altered, the protein’s primary structure changes, and that disrupts the way the chain folds. The specific side chains interact differently, affecting hydrophobic cores, hydrogen bonds, ionic interactions, and disulfide bonds, so the final three-dimensional structure can be different. This is why mutations that modify the amino acid sequence can change the protein’s shape and often its function. Some mutations don’t change the amino acid (silent) and may not affect structure, or can cause larger disruptions like frameshifts or nonsense mutations, but the fundamental connection is that altering the amino acid sequence changes the primary structure and thus the 3D structure.