Question

Describe the primary structure of polypeptide.

Answer 1

I'm thinking: a chain of hundreds or thousands of amino acids.

Answer 2

"Primary structure" simply refers to the sequence of amino acids in a polypeptide. This is as opposed to the secondary structure, which refers to the structure of repetitive structures (alpha helices and beta sheets), tertiary structure which refers to the folding of large moieties, and quaternary structure, which refers to the combination of multiple polypeptides to form a functional protein.

On the other hand, the polypeptide itself has to be modified by the covalent addition of various substances to certain amino acids. For examples, phosphorylation (a phosphate group) and glycosylation (a sugar group or chain) are common modifications. Polypeptides can be attached to others covalently via sulfhydryl bonds (cysteine to cysteine). Finally, some proteins require the addition of accessory molecules, such as heme in hemoglobin and chlorophyll.

Answer 3

Hope it helps you.

Answer 4

Thank you! xx