Protein Structure and Function Flashcards

Which level of protein structure refers to the sequence of amino acids in a polypeptide chain?

Answer: Primary structure

Primary structure is the linear sequence of amino acids linked by peptide bonds, which ultimately determines all higher levels of protein structure.

Alpha-helices and beta-pleated sheets are examples of which level of protein structure?

Answer: Secondary

Secondary structure describes local folding patterns stabilized by hydrogen bonds between backbone amide and carbonyl groups.

Which bond is primarily responsible for maintaining the tertiary structure of a protein in an aqueous environment?

Answer: Hydrophobic interactions

Hydrophobic interactions drive the burial of nonpolar side chains in the protein core and are the dominant force in tertiary structure stabilization.

Hemoglobin is an example of a protein with which level of structural organization?

Answer: Quaternary

Quaternary structure describes the assembly of two or more polypeptide subunits, as seen in hemoglobin's four globin chains.

Which amino acid can form disulfide bonds that stabilize protein structure?

Answer: Cysteine

Cysteine residues contain thiol (-SH) groups that can be oxidized to form covalent disulfide (-S-S-) bonds between chains or within a single chain.

Protein denaturation by heat or chemicals disrupts all levels of structure EXCEPT which?

Answer: Primary

Denaturation disrupts non-covalent interactions and disulfide bonds but does not break the covalent peptide bonds that define primary structure.