Question

The factory of ribosome in a cell is:
A. Endoplasmic reticulum
B. Nucleolus
C. Mitochondria
D. Golgi body

Answer 1

Hint: It is known as the site of ribosomal biogenesis. It helps in protein synthesis too when the complete ribosome is formed from ribosomal subunits which combine together to form ribosomes.

Complete answer:
Ribosomes are small particles which are found in the cytoplasm of cells attached to the endoplasmic reticulum and these are responsible for protein synthesis. It has RNA and proteins which helps in protein synthesis.

Now the question is related to the factory of ribosomes and the factory of ribosomes is Nucleolus. Nucleolus is found in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. It is also responsible for ribosomal RNA synthesis, its processing and ribosomal subunit assembly. Nucleoli are generally made up of protein, DNA and RNA. Ribosomal subunits from proteins and rRNA are made by nucleolus, nucleolus send these subunits to the rest of cells and finally they get combined into the complete ribosome which further play a role in making the protein. Therefore, this nucleolus plays an important role in making the protein.

Hence, the correct answer is option (B).

Additional information:
Ribosome is a cell organelle and they are generally found floating in the cytoplasm or they are found attached to the endoplasmic reticulum. These are present in large numbers in all the living cells and these are the main site of protein synthesis. There are three types of ribosomes i.e., rRNA, mRNA and tRNA. rRNA is ribosomal RNA, mRNA is messenger RNA and tRNA is transfer RNA. All of them have different functions but important ones. Messenger RNA acts as carrying the information whereas the tRNA helps mRNA for that.

Note: Ribosomes are mainly responsible for protein synthesis and these ribosomes are made from ribosomal subunits which combine together and complete into ribosomes. Nucleolus make these subunits. All the major functions like ribosome biogenesis, rRNA synthesis are performed by nucleolus therefore it is called as the factory of ribosome.