Select ALL statements that apply to Ribozymes:
A responsible for carrying out protein synthesis
B. enzymes that transcribe rRNA
C. possess enzymatic activity 0.
D. are composed of one small and one large subunit, each made up of RNA
E are composed of RNA nucleotides only
The Correct Answer and Explanation is :
The correct statements about ribozymes are:
C. possess enzymatic activity
E. are composed of RNA nucleotides only
Explanation:
Ribozymes are a class of RNA molecules that have the ability to catalyze chemical reactions, much like protein enzymes. However, instead of being composed of proteins, ribozymes are made entirely of RNA. Their catalytic properties challenge the old belief that only proteins could act as enzymes. Ribozymes were first discovered in the 1980s, and this discovery helped expand our understanding of the versatility and function of RNA.
C. possess enzymatic activity
Ribozymes are unique in that they possess true enzymatic activity. They catalyze specific biochemical reactions without the need for proteins. Their enzymatic function is typically related to the processing or splicing of RNA molecules, such as in the case of group I and II introns or the ribosome’s catalytic site (peptidyl transferase activity).
E. are composed of RNA nucleotides only
Ribozymes are made of RNA and do not require any protein components for their catalytic activity. The sequence of RNA nucleotides in ribozymes folds into a three-dimensional structure, which is crucial for their ability to carry out chemical reactions. This makes ribozymes fundamentally different from most enzymes, which are typically proteins.
Why the other statements are incorrect:
A. responsible for carrying out protein synthesis
This statement is inaccurate because ribozymes themselves are not directly responsible for protein synthesis. While the ribosome (which contains ribosomal RNA, a type of ribozyme) plays a crucial role in protein synthesis, ribozymes alone do not perform this function. Instead, the ribosome’s rRNA catalyzes peptide bond formation during translation.
B. enzymes that transcribe rRNA
This is incorrect because ribozymes do not transcribe RNA. RNA transcription is carried out by RNA polymerase, not by ribozymes. Ribozymes typically catalyze reactions involving RNA processing or splicing.
D. are composed of one small and one large subunit, each made up of RNA
This statement is a description of the ribosome, which is not entirely made of RNA, but rather a complex of both rRNA and proteins. Ribozymes, by contrast, are purely RNA molecules and do not have separate “small” or “large” subunits.