Question

In my textbook
"It is evident that a polypeptide's final shape, its tertiary structure, is determined by its primary structure"

Isnt the final shape quaternary structure? Why does my textbook says the final shape is tertiary structure

Answer 1

yea it can be in quartnery str. but its found in really rare case mostly they are found in tertiary str.

Answer 2

quartenary structure (if i remember correctly) is ht structure of several proteins. like ribosomal units.

Answer 3

so if the question ask for which structure has the most complex shape
will the answer be tertiary structure then?
cuz quarternary is made up of tertiary

Answer 4

Erm, close but not quite.

Each higher level is made up of lower level structure. The primary structure is just the unfolded sequence of the protein.

The line between secondary structure and tertiary structure isn't as clear: secondary structural elements are small, local foldings of the polypeptide into small, local structures like helices, loops and beta sheets. Tertiary structural elements are made out of secondary structural elements - for example, a lobe or domain of a kinase made out of a small beta sheet and a couple of helices. It's sort of the "whole protein level" of structure.

Quaternary structure refers to assembly of multiple subunit proteins into a functional macro-molecule.

If the question asks for which has the most complex shape, I'd go with quaternary.