Final answer:
The correct statement regarding proteins is that the primary structure provides the sequence of amino acids. Contrary to one of the statements, proteins typically have right-handed α-helices. Additionally, adult human hemoglobin is an example of quaternary, not tertiary structure, and the first amino acid in a polypeptide is the N-terminal, not the C-terminal. o primary structure of proteins gives the positional information of amino acids.
Step-by-step explanation:
The correct statement with respect to proteins is that the primary structure of proteins gives the positional information of amino acids. Proteins have different levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is defined by the sequence of amino acids in the polypeptide chain. Contrary to the statement that suggests only left-handed helices are observed in proteins, proteins typically consist of right-handed α-helices, as determined by X-ray crystallography studies done by Linus Pauling and Robert Corey.
Furthermore, adult human hemoglobin is actually an example of quaternary structure, not tertiary, because it is made up of four polypeptide chains. Tertiary structure refers to the three-dimensional folding of a single polypeptide chain due to interactions between side chains, whereas quaternary structure is the arrangement of multiple such tertiary structures.
Last but not least, the first amino acid in a polypeptide chain is known as the N-terminal amino acid, not the C-terminal amino acid, which is at the other end of the chain.