GENERAL HISTOLOGY

Detailed explanation-1: -Nearly all the proteins required by cells are synthesised by ribosomes. Ribosomes are found ‘free’ in the cell cytoplasm and also attached to rough endoplasmic reticulum. Ribosomes receive information from the cell nucleus and construction materials from the cytoplasm.

Detailed explanation-2: -The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function. The rough endoplasmic reticulum has on it ribosomes, which are small, round organelles whose function it is to make those proteins.

Detailed explanation-3: -The free-ribosomes synthesize soluble cytoplasmic proteins, peripheral membrane proteins, mitochondrial proteins, chloroplast proteins, peroxisomal and nuclear proteins, etc. In short, free-ribosomes are responsible for the production of all the proteins that are found within the cell and are present in the cytosol.

Detailed explanation-4: -Ribophorin, also known as a ribosome receptor protein, is a transmembrane glycoprotein that aids in the binding of ribosomes to the endoplasmic reticulum’s outer surface, generating rough endoplasmic reticulum.

Detailed explanation-5: -The ribosome that is synthesizing the protein is directly attached to the ER membrane. These membrane-bound ribosomes coat the surface of the ER, creating regions termed rough endoplasmic reticulum, or rough ER (Figure 12-36A).