Question

Ribosomal RNA is actively synthesized in
a. Lysosomes
b. Nucleolus
c. Nucleoplasm
d. Ribosomes.

Answer 1

Hint: RNA is also known as RIBONUCLEIC ACID due to the presence of ribose sugar in its structure. Ribonucleic acid is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. The most common role of RNA is that it converts information possessed by DNA into proteins
Types of RNA:- There are four types of RNAs
> mRNA - Messenger RNA: this helps to code amino acids during the process of translation
> tRNA - Transfer RNA: this helps to bring amino acids in association with ribosomes during the translation process.
> rRNA - Ribosomal RNA: With ribosomal proteins, makes up the ribosomes, the organelles that translate the mRNA.
> snRNA - Small nuclear RNA: With proteins, forms complexes that are used in RNA processing in eukaryotes.

Complete answer:
a. LYSOSOMES :- They are also known as suicidal bags because they are involved in autolysis, that is they start to eat their own cells when disturbance occurs inside cellular mechanisms. Ribosomes are not present in these. So are not involved in RNA synthesis. Hence, this option is incorrect.
b. Nucleolus:- a spherical body of the nucleus of most eukaryotes that becomes enlarged during protein synthesis. Nucleolus is made up of RNA and proteins basically. So they are actively involved in synthesis of ribosomal RNA. Thereby, this option is correct.
c. NUCLEOPLASM:- The nucleoplasm is a type of protoplasm that is made up mostly of water, a mixture of various molecules, and dissolved ions. Its primary role is to support chromosomes and nucleoli and is not involved in RNA synthesis. So, this option is incorrect.
d. RIBOSOMES :- They are spherical structures which are usually present on ROUGH ENDOPLASMIC RETICULUM . They produce proteins and not RNA. Hence, this option is also incorrect.

Our required answer is b. NUCLEOLUS.

Note: Nucleolus is also known as ribosomal factory. The proteins of ribosomes are synthesised in cytoplasm which is transported to the nucleus and finally to the nucleolus. These complex structures, of ribosomal RNA which physically move along an mRNA molecule, catalyse the assembly of amino acids into protein chains.