LIFE SCIENCE

Detailed explanation-1: -The most prominent substructure within the nucleus is the nucleolus (see Figure 8.1), which is the site of rRNA transcription and processing, and of ribosome assembly. As discussed in the preceding chapter, cells require large numbers of ribosomes to meet their needs for protein synthesis.

Detailed explanation-2: -Molecules of rRNA are synthesized in a specialized region of the cell nucleus called the nucleolus, which appears as a dense area within the nucleus and contains the genes that encode rRNA.

Detailed explanation-3: -In eukaryotes, pre-rRNAs are transcribed, processed, and assembled into ribosomes in the nucleolus, while pre-tRNAs are transcribed and processed in the nucleus and then released into the cytoplasm where they are linked to free amino acids for protein synthesis.

Detailed explanation-4: -The nucleolus is the largest subnuclear compartment of the cell that forms around regions of chromosomes containing stretches of tandem repetitive ribosomal RNA (rRNA) genes, known as nucleolar organizer regions (NORs).

Detailed explanation-5: -Ribosomal RNA is synthesised in the dense area of the nucleus called the nucleolus. Nucleolus has genes which codes for rRNA.