Which of the following statements is true more than one answ

Which of the following statements is true?  (more than one answer may be correct)

a) Nonpolar amino acids tend to be found in the interior of proteins.

b) The polypeptide backbone is free to rotate about each peptide bond.

c) The sequence of the atoms in the polypeptide backbone varies between different proteins.

d) Peptide bonds are the only covalent bonds that can link together a single polypetide chain.

Solution

The peptide bond is formed between COOH group of one amino acid and NH₂ group of another amino acid. The peptide bond cannot rotate freely in the backbone because it is connected by other bonds occuring in the amino acids such as disulfide bonds etc. The peptide bonds always formed between COOH group of one amino acid and NH₂ group of another amino acid. Peptide bonds are covalent bonds and link amino acids in the polypeptide and the amino acid side chains contain disufide bonds. Nonpolar amino acids are hydrophobic in nature and they are found in the interior of the protein structures. Option a is correct.