Which part of the nucleus is responsible for assembling ribosomes and ribosomal RNA?

• A. The mitochondria.
• B. Nuclear Envelope.
• C. Nuclear pores.
• D. Nucleolus.

Answer: (D)

Verified step by step guidance

1. Understand the function of the nucleolus: The nucleolus is a prominent sub-structure within the nucleus of eukaryotic cells. Its primary function is to assemble ribosomes, which are essential for protein synthesis.
2. Recognize the role of ribosomal RNA (rRNA): Ribosomal RNA is a key component of ribosomes. The nucleolus is responsible for transcribing and assembling rRNA, which combines with proteins to form ribosomal subunits.
3. Differentiate between the nucleolus and other nuclear components: The nuclear envelope surrounds the nucleus and contains nuclear pores that regulate the passage of molecules. However, these structures are not involved in ribosome assembly.
4. Clarify the role of mitochondria: Mitochondria are organelles responsible for energy production in the cell, not for ribosome assembly or rRNA synthesis.
5. Conclude that the nucleolus is the correct answer: Based on its specific function in ribosome and rRNA assembly, the nucleolus is the part of the nucleus responsible for these processes.