Question

One of the following enzymes is not a protein:

• A. DNAase.
• B. Abzyme.
• C. Eco RI.
• D. Ribozyme.

Hint:

Ribozymes are catalytic RNA molecules, the one common exception to enzymes being proteins.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks which of the four listed biological catalysts is not made of protein, since it is testing whether the student knows about catalysts built from RNA rather than protein.

Step 2: Key Concept:
Almost all enzymes in the body are proteins, folded chains of amino acids that speed up chemical reactions. A small, important exception exists: certain RNA molecules can also act as catalysts. These are called ribozymes, and they are made of ribonucleic acid, not protein.

Step 3: Detailed Explanation:
DNAase is a protein enzyme that cuts DNA into fragments, it is built from amino acids like typical enzymes.
Abzyme, short for antibody enzyme, is an antibody that has been engineered or selected to carry out catalysis, since antibodies are proteins, an abzyme is a protein.
Eco RI is a bacterial restriction enzyme that cuts DNA at a specific sequence, it too is a protein enzyme.
Ribozyme, in contrast, is an RNA molecule with catalytic ability, for example the RNA component of the ribosome that helps form peptide bonds during protein synthesis, or self splicing RNA introns. Ribozymes are made of nucleotides, not amino acids, so they are not proteins.

Step 4: Final Answer:
The enzyme that is not a protein is the ribozyme, since it is built from RNA rather than a chain of amino acids.