Final answer:
When proteins are heated, they undergo denaturation, which is the process of losing their shape and structure. Heat affects the secondary and tertiary structures of a protein, causing unfolding and loss of function.
Step-by-step explanation:
When proteins are heated, they undergo denaturation, which is the process of losing their shape and structure. Denaturation can be reversible or irreversible, depending on the specific protein and the conditions. Specifically, heat affects the secondary and tertiary structures of a protein.
Secondary structure, which refers to the arrangement of amino acids within a protein chain, is disrupted by heat, causing the protein to unfold. Tertiary structure, which refers to the overall three-dimensional shape of a protein, is also affected by heat, leading to further unfolding and loss of function.