GENERAL HISTOLOGY

Detailed explanation-1: -Proteins are assembled at organelles called ribosomes. When proteins are destined to be part of the cell membrane or exported from the cell, the ribosomes assembling them attach to the endoplasmic reticulum, giving it a rough appearance.

Detailed explanation-2: -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).

Detailed explanation-3: -The RER is termed “rough” due ribosomal attachments to the surface compared to the SER, which does not have ribosomes.

Detailed explanation-4: -The answer is the presence of ribosomes on the surface. The rough endoplasmic reticulum contains ribosomes on the surface whereas the smooth endoplasmic reticulum does not. Ribosomes are another type of organelle that are made of ribosomal RNA and protein.

Detailed explanation-5: -∙ If ribosomes are found attached to the endoplasmic reticulum, it is called rough endoplasmic reticulum or RER. The endoplasmic reticulum without ribosomes are called smooth endoplasmic reticulum or SER. ∙ RER is associated with protein synthesis and SER is associated with lipid sythesis.