GENERAL HISTOLOGY

Detailed explanation-1: -Definition. Endoplasmic reticulum is a network of membranes inside a cell through which proteins and other molecules move. Proteins are assembled at organelles called ribosomes.

Detailed explanation-2: -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-3: -Ribosomes are called “protein factories” of the cell.

Detailed explanation-4: -Protein synthesis Synthesis of new proteins starts in the nucleus, where ribosomes get their instruction to begin the process. Sections of DNA (genes), encoding a specific protein, are copied over to messenger RNA (mRNA) strands in a process called transcription.

Detailed explanation-5: -All living cells contain ribosomes, tiny organelles composed of approximately 60 percent ribosomal RNA (rRNA) and 40 percent protein. However, though they are generally described as organelles, it is important to note that ribosomes are not bound by a membrane and are much smaller than other organelles.