Ribozymes are RNA molecules with enzymatic properties that can catalyze specific biochemical reactions, similar to protein enzymes. Which of the following best describes the unique properties and functions of ribozymes? (a) They act as structural components of chromosomes, providing stability during mitosis. (b) They primarily function to enhance the translation process by binding amino acids. (c) They are involved in editing and splicing their own RNA sequences and other RNA substrates. (d) They catalyze peptide bond formation during protein synthesis at the ribosome. Ribozymes are RNA molecules with enzymatic properties that can catalyze specific biochemical reactions, similar to protein enzymes. Which of the following best describes the unique properties and functions of ribozymes? (a) They act as structural components of chromosomes, providing stability during mitosis. substrates. (d) They catalyze peptide bond formation during protein synthesis at the ribosome.
The Correct Answer and Explanation is:
Correct Answer: (c) They are involved in editing and splicing their own RNA sequences and other RNA substrates.
Explanation:
Ribozymes are RNA molecules that possess catalytic properties, allowing them to facilitate specific biochemical reactions without being proteins. This is a unique and significant discovery because enzymes were traditionally understood to be proteins. Ribozymes challenge this notion by demonstrating that RNA, a nucleic acid, can also function as a biological catalyst.
The most notable function of ribozymes lies in RNA processing. One of their primary roles is in RNA splicing, where they catalyze the removal of introns (non-coding regions) from pre-messenger RNA. For instance, self-splicing introns, such as those found in certain protozoans and mitochondria, are classic examples of ribozymes. These RNA sequences can excise themselves from the primary RNA transcript without the need for protein enzymes, a critical step in producing mature and functional mRNA.
Ribozymes also play a role in other RNA-related reactions, such as cleaving or ligating RNA strands, and can be engineered in laboratories to target specific RNA molecules, which has made them valuable tools in biotechnology and medicine. Their activity is highly specific, meaning they bind only to particular RNA sequences to perform their function.
Option (d), stating that ribozymes catalyze peptide bond formation during protein synthesis, refers to a specialized component of the ribosome—the peptidyl transferase center found in the large ribosomal subunit. Although this part is made of ribosomal RNA and technically qualifies as a ribozyme, the unique defining feature of most ribozymes is their role in RNA processing rather than peptide synthesis.
Options (a) and (b) are incorrect because they describe structural proteins and tRNAs, not ribozymes. Therefore, option (c) best captures the unique catalytic role of ribozymes in RNA editing and splicing.
