Here in this example question, it says, determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein. For the first one, it says, side chains interact to form disulfide bonds. So remember, disulfide bonds are a key characteristic of a tertiary structure. So here, this represents a tertiary structure. Next, peptide bonds join amino acids into a polypeptide chain. This is how we begin our journey towards a fully functional protein. This represents our primary structure. Remember, amino acids form these peptide bonds with one another, forming and linking together to form a long peptide chain.
Next, two peptide chains are held together by hydrogen bonding. Alright. So they're talking about two chains. Now here, that couldn't be primary or secondary. Because remember, those happen amongst one chain. So that means it's either going to be tertiary or quaternary. Here they're saying two polypeptide chains are held together by hydrogen bonding. This has to be a quaternary structure because here we can have these types of interactions that connect different chains with one another, Eventually, this will lead up to our quaternary structure later on.
Next, hydrogen bonding between amino acids in the same polypeptide gives a coiled shape to the protein. Coiled shape is a reference to our alpha helices or alpha helix. Remember, that is indicative of a secondary structure. So this will represent our different types of protein structures based on these four statements.
