Which type of proteins exhibit only primary and secondary structure?

two bonds that can rotate in space between each amino acid in the backbone of the primary sequence. These restricted movements, when repeated through several amino acids in a chain, yield the two main types of protein secondary structure: the alpha (α) helix and the beta (β) strand.

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Explanation:

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in