LIFE SCIENCE

Detailed explanation-1: -A darkly stained area within the nucleus, called the nucleolus (plural = nucleoli), aggregates the ribosomal RNA with associated proteins to assemble the ribosomal subunits that are then transported through the nuclear pores into the cytoplasm.

Detailed explanation-2: -A ribosome is made out of RNA and proteins, and each ribosome consists of two separate RNA-protein complexes, known as the small and large subunits.

Detailed explanation-3: -Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins by mass.

Detailed explanation-4: -Answer and Explanation: The cell structures where proteins are made are called ribosomes. Ribosomes are organelles made of ribosomal RNA (rRNA) and protein. They exist in the cytoplasm of the cell and are the site of protein synthesis in all cells.

Detailed explanation-5: -Ribosomes are composed of two subunits, the large and the small subunit, both of which consist of ribosomal RNA (rRNA) molecules and a variable number of ribosomal proteins. Several factor proteins catalyze different steps of protein synthesis by binding transiently to the ribosome.