AP BIOLOGY

Detailed explanation-1: -Explanation : Nucleolus is a darkly pigmented portion of nucleus . It produces rRNA which moves from there to cytoplasm and join with proteins to form ribosomes. So it concludes that nucleolus is the portion of cell which forms ribosomes.

Detailed explanation-2: -The nucleolus is a spherical structure found in the cell’s nucleus whose primary function is to produce and assemble the cell’s ribosomes.

Detailed explanation-3: -The nucleolus is a ribosome production factory, designed to fulfill the need for large-scale production of rRNAs and assembly of the ribosomal subunits.

Detailed explanation-4: -At the nucleolus, a long ribosomal RNA (rRNA) precursor molecule is transcribed from DNA, processed into three mature RNAs, and packaged together with specific proteins to make the large and small ribosomal subunits.

Detailed explanation-5: -Eukaryote ribosomes are produced and assembled in the nucleolus. Ribosomal proteins enter the nucleolus and combine with the four rRNA strands to create the two ribosomal subunits (one small and one large) that will make up the completed ribosome (see Figure 1).