Question

Which of the following rRNAs acts as structural RNA as well as ribozyme in bacteria?
A)23S rRNA
B)5.8S rRNA
C)5S rRNA
D)18 s rRNA

Answer 1

Hint: The bacteria have both DNA and RNA as their genetic material. The DNA is present along with the proteins forms the chromosomal structure whereas the RNA is a double-stranded circular structure. The ribosome in bacteria is of 70s type.

Complete answer:
To solve this question, we must know about the composition of bacterial rRNA.
Ribosomes are the important organelles in a cell which is responsible for the synthesis of proteins. In prokaryotes, the ribosome is synthesised in the cytoplasm. All the prokaryotic cells including the bacteria have 70S RNA. The 70s RNA is made up of two subunit 30S and 50S.

30S subunit- It is made up of 16S rRNA. It is coded by 16S rRNA gene. It is a cytosolic homologue in prokaryotes. The 16S rRNA is used as a tool to identify bacterial strains as it is composed of specific nucleotide sequences.
50S subunit- It is made up of 23S and 5S rRNA.
The 23S rRNA shows peptidyl transferase activity which catalyses peptide bond formation in proteins or amino acid chains. It serves as a structural component for the larger subunit of bacterial ribosome. These are the protein making giant ribozymes.
 The 5S subunit enhances protein synthesis and helps in stabilizing the structure of the ribosome.

5.8S and 18S rRNA units are present in eukaryotes.

Hence, the correct answer is option (A)

Note: S stands for svedbergs. It is the unit used to measure the sedimentation rate of molecules in a centrifuge. It is dependent on the mass and shape of the molecule. The bacterial or the prokaryotic RNA sediments faster than the eukaryotic RNA.