Biology · Biomolecules · NEET
No. This is the exact trap NEET uses. NCERT says 'almost all enzymes are proteins' — not ALL. Most enzymes are made of protein, but some nucleic acids (RNA) also act as enzymes. So the correct statement is 'almost all enzymes are proteins,' and any option that says 'all enzymes are proteins' is wrong.
A ribozyme is a nucleic acid (RNA) that behaves like an enzyme. In NCERT words: 'There are some nucleic acids that behave like enzymes. These are called ribozymes.' So a ribozyme is a non-protein enzyme. It is made of RNA, not amino acids.
A ribozyme is a nucleic acid (RNA). This is the point NEET tests. When a question asks for a 'non-proteinaceous enzyme,' the answer is ribozyme. Options like lysozyme, ligase and deoxyribonuclease are all proteins, so they are wrong.
An enzyme is the broad group — any biocatalyst that speeds up a reaction. Most enzymes are proteins (chains of amino acids). A ribozyme is a special kind of enzyme made of RNA instead of protein. So a ribozyme IS an enzyme, but a non-protein one. Remember: all ribozymes are enzymes, but not all enzymes are ribozymes.
Yes, protein enzymes follow the same 4 levels of protein structure. NCERT says an enzyme, like any protein, has a primary structure (amino acid sequence), a secondary structure and a tertiary structure. When the chain folds, it forms pockets. One such pocket is the active site where the substrate fits.
RuBisCO (Ribulose bisphosphate Carboxylase-Oxygenase) is the most abundant enzyme and most abundant protein in the whole biosphere. This is a direct NCERT fact and a repeated NEET point. Do not confuse it with collagen, which is the most abundant protein only in the animal world.
A non-proteinaceous enzyme is:
Identify the correct statements about biomolecules: A. Lipids are generally water soluble. B. Proteins are polypeptides. C. Polysaccharides are long chains of sugars. D. Adenine and guanine are substituted pyrimidines. E. Almost all enzymes are proteins.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. Enzymes are biomolecules. Protein enzymes belong to the protein group and ribozymes belong to the nucleic acid group. All enzymes are biocatalysts made by living cells.
Most reactions in cells are sped up by proteins with an active site. But a few RNA molecules can also fold into a shape that speeds up a reaction. Because these RNA molecules exist, NCERT carefully writes 'almost all' instead of 'all.' The RNA enzymes are ribozymes.
A ribozyme is made of RNA. It is a ribonucleic acid with catalytic power. NCERT groups ribozymes as nucleic acids that behave like enzymes.
An enzyme lowers the activation energy of a reaction and speeds it up greatly, without being used up. For example, carbonic anhydrase speeds up the making of carbonic acid about 10 million times.
Ribozymes also fold into a 3D shape and bind their substrate to catalyse a reaction, similar in principle to protein enzymes. For NEET, the key fact is simply that ribozymes are non-protein (RNA) enzymes.
