Endoplasmic Reticulum and Golgi Questions and Answers

Answer: C

The Golgi would be most abundant in a gland.

The Golgi apparatus modifies, sorts and packages proteins into secretory vesicles. Gland cells, such as the acinar cells of the pancreas or the goblet cells of the gut, secrete large amounts of enzymes, hormones or mucus and so have a large, well-developed Golgi.

Muscle cells are specialised for contraction, mature red blood cells have no organelles at all, and bone cells secrete matrix at a far lower rate than gland cells. None of them would have as much Golgi as a secretory gland.

Answer: B

These monooxygenases are present in the Smooth endoplasmic reticulum.

The cytochrome P450 monooxygenases, which add an -OH group using O₂ and NADPH, sit in the membranes of the smooth ER (the microsomal fraction), especially in liver and in steroid-producing cells. They hydroxylate steroids during their synthesis and make drugs and toxins more water-soluble for excretion.

Peroxisomes hold oxidases and catalase rather than these hydroxylases, the Golgi complex processes and sorts proteins, and the rough ER is the site of protein synthesis on ribosomes.

Answer: C

The lysosomal marker enzyme is acid phosphatase.

In cell fractionation, each organelle is traced by an enzyme found only in it. Lysosomes contain acid hydrolases that work at their internal pH of about 5, and acid phosphatase is the classic marker. It was the enzyme whose latent activity led Christian de Duve to discover lysosomes.

Succinate dehydrogenase, of the inner mitochondrial membrane, is the marker for mitochondria, and pyruvate dehydrogenase is also mitochondrial. Phospholipases occur in many compartments and are not used as a lysosomal marker.