The structure of a protein can be denatured by heat.

Explanation

**Step-by-Step Solution:**

1. **Understanding Protein Structure**: Proteins are made up of long chains of amino acids that fold into specific three-dimensional shapes. These shapes are crucial for their function.

2. **Denaturation Definition**: Denaturation refers to the process where a protein loses its native structure due to the disruption of non-covalent interactions and disulfide bonds, leading to a loss of biological activity.

3. **Effect of Heat on Proteins**: When heat is applied to a protein, it increases the kinetic energy of the molecules. This increased energy causes the protein molecules to vibrate more vigorously.

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