What is the primary function of the nucleolus in eukaryotic cells?

• A. Production of ATP through cellular respiration
• B. Synthesis of ribosomal RNA (rRNA) and assembly of ribosome subunits
• C. Storage of genetic information
• D. Modification and packaging of proteins

Answer: (B)

Verified step by step guidance

1. Understand the role of the nucleolus: The nucleolus is a prominent structure within the nucleus of eukaryotic cells, primarily involved in the synthesis of ribosomal RNA (rRNA) and the assembly of ribosome subunits.
2. Identify the components involved: Ribosomal RNA (rRNA) is a key component of ribosomes, which are essential for protein synthesis in the cell.
3. Explore the process: The nucleolus synthesizes rRNA and combines it with proteins to form the subunits of ribosomes. These subunits are then transported out of the nucleus to the cytoplasm where they become functional ribosomes.
4. Differentiate from other functions: While the nucleolus is involved in rRNA synthesis and ribosome assembly, it is not directly involved in ATP production, storage of genetic information, or modification and packaging of proteins.
5. Connect to cellular function: Ribosomes, assembled with the help of the nucleolus, are crucial for translating mRNA into proteins, which are vital for numerous cellular functions.