Question

Alpha helixes and beta sheets are the examples of ................... protein organisation.

• A. Primary structure
• B. Secondary structure
• C. Tertiary structure
• D. Quaternary structure

Answer 1

The correct option is B Secondary structure

Alpha helix structure of the protein is a form of the secondary structure of the protein. It is formed due to the formation of hydrogen bonds between backbone amide and carbonyl groups. The hydrogen bonds linkage is formed between N-H group of one amino residue with a C=O group of another amino acid, which is placed in 4 residues earlier. Each turn of alpha helix contains 3.6 amino acid residue.

β-pleated secondary protein structure is formed by the parallel or anti-parallel polypeptide chain linked together by H - bonds. It is stabilized by the hydrogen bonds formed between NH and CO of the adjacent polypeptide chain. The distance between the adjacent amino acids is 3.5 A${}^o$.

So, the correct answer is option B.