AP BIOLOGY

Detailed explanation-1: -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. Smooth endoplasmic reticulum lacks ribosomes and helps synthesize and concentrate various substances needed by the cell.

Detailed explanation-2: -The rough ER, which is covered by ribosomes on its outer surface, functions in protein processing. The smooth ER is not associated with ribosomes and is involved in lipid, rather than protein, metabolism.

Detailed explanation-3: -Assertion :The endoplasmic reticulum which lacks ribosomes is called smooth endoplasmic reticulum (SER). Reason: SER is mainly involved in protein synthesis. Q.

Detailed explanation-4: -Smooth endoplasmic reticulum is a network of tubular membranes within the cytoplasm of the cell, occurring either with a smooth surface and are devoid of ribosomes.

Detailed explanation-5: -Smooth E R (SER) is associated with the production and metabolism of fats and steroid hormones. It is ‘smooth’ because it is not studded with ribosomes and is associated with smooth slippery fats.