Is the final shape of a polypeptide a tertiary structure or a quaternary structure?In my Nelson 12,pg 46, "It is evident that a polypeptide 's final shape, it's tertiary structure, is determined...

Is the final shape of a polypeptide a tertiary structure or a quaternary structure?

In my Nelson 12,pg 46, "It is evident that a polypeptide 's final shape, it's tertiary structure, is determined by its primary structure"

So the final shape is not quaternary but tertiary? Why is that so?

Asked on by lovekblue

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jgeertz | College Teacher | (Level 1) Associate Educator

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It depends.

There are four structure levels in polypeptides and proteins. The primary structure of a polypeptide determines its secondary, tertiary, and quaternary structure.

Primary structure is simply the amino acid sequence of the polypeptide chain with reference to the locations of covalent bonds.

Secondary structure is the arrangement of amino acids in the polypeptide. A single polypeptide can contain multiple secondary structures, most often alpha-helixes and beta-pleated sheets.

Tertiary structure is the three dimensional arrangement of atoms in the polypeptide. For proteins composed of only a single polypeptide molecule, tertiary structure is the highest level of structure.

Quaternary structure describes multiple polypeptide molecules, each called a monomer. Proteins of greater weight are usually made up of two or more non-covalently linked monomers. The arrangement of these monomers is quaternary structure.

Sources:

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