Which of the following is/are true about ribozymes? A. They are found in the nucleus B. They are not proteins C. They are RNA molecules D. Some intronic RNAs are ribozymes E. All of the above
The Correct Answer and Explanation is:
Correct Answer: E. All of the above
Explanation:
Ribozymes are fascinating biological molecules that serve as RNA enzymes, meaning they catalyze chemical reactions similar to protein enzymes. Each of the provided options gives accurate information about ribozymes.
A. They are found in the nucleus:
This is true. Ribozymes can be located in the nucleus of eukaryotic cells, where they often play a role in RNA processing events. For example, during RNA splicing, some ribozymes participate in the removal of introns from precursor messenger RNA (pre-mRNA). The nucleus is the central location for such RNA processing activities.
B. They are not proteins:
This statement is also correct. Unlike typical enzymes, which are made of proteins, ribozymes are composed entirely of RNA. They are unique because their enzymatic function is not dependent on amino acid sequences or structures. Instead, the catalytic activity comes from the complex three-dimensional folding of the RNA itself.
C. They are RNA molecules:
Yes, this is the definition of a ribozyme. Ribozymes are strands of ribonucleic acid (RNA) that exhibit enzymatic properties. They are capable of catalyzing reactions such as cleavage and ligation of RNA strands and even peptide bond formation in the ribosome.
D. Some intronic RNAs are ribozymes:
This is true as well. Some introns, particularly those classified as Group I and Group II introns, can catalyze their own excision from the primary RNA transcript. These self-splicing introns function as ribozymes because they carry out their splicing reactions without the need for protein enzymes.
E. All of the above:
Since all the statements (A to D) are accurate descriptions of ribozymes, the correct choice is E.
Ribozymes highlight the versatility of RNA and support the RNA world hypothesis, which proposes that early life may have relied on RNA for both genetic information storage and catalytic activity.
