Question

question 9 of 10
which of the following correctly describes the primary and tertiary structures of a protein?
a. the primary structure is the proteins shape; the tertiary structure is the amino acid chain.
b. the primary structure is the amino acid chain; the tertiary structure is the proteins shape.
c. the primary structure is the amino acid chain; the tertiary structure is the mrna sequence.
d. the primary structure is the mrna sequence; the tertiary structure is the amino acid chain.

Explanation:

• Primary structure: It is the linear sequence of amino acids in a protein. This is the most basic level of protein structure.
• Tertiary structure: It is the three - dimensional shape of a single polypeptide chain. It is formed due to interactions such as hydrophobic interactions, hydrogen bonds, disulfide bridges etc. among the amino acid residues.

Now let's analyze each option:

• Option A: Incorrect. The primary structure is the amino acid chain, not the protein's shape. The tertiary structure is the protein's shape.
• Option B: Correct. The primary structure is the amino acid chain and the tertiary structure is the protein's shape.
• Option C: Incorrect. The tertiary structure is not the mRNA sequence. The mRNA sequence is involved in protein synthesis (translation) but is not a part of the protein's structure.
• Option D: Incorrect. The primary structure is the amino acid chain, not the mRNA sequence.

Answer:

B. The primary structure is the amino acid chain; the tertiary structure is the protein's shape.