Question
Hemoglobin is a conjugated protein consisting of four polypeptide chains with attached heme groups.
(a) State the level of protein structure at which the polypeptide chains of hemoglobin are combined.
(b) Explain the shape of the polypeptide chain at X.
(c) Outline the role of tRNA in hemoglobin synthesis.
Answer/Explanation:
(a) The level of protein structure at which the polypeptide chains of hemoglobin are combined is the quaternary structure. This is when two or more separate polypeptide chains (subunits) join together to form a functional protein.
(b) The shape of the polypeptide chain at X is likely an alpha helix, which is a common secondary structure. It forms when the chain coils into a spiral shape, held together by hydrogen bonds between nearby amino acids. This shape is stable and helps the protein keep its structure.
(c) During hemoglobin synthesis, tRNA (transfer RNA) plays a key role in translation, the process of building a protein from mRNA instructions. Each tRNA carries a specific amino acid and matches it to the correct codon on the mRNA at the ribosome. This helps build the polypeptide chains that will later combine to form hemoglobin.