In which cell would you find the most smooth ER?
a. Pancreatic cell that secretes digestive enzymes
b. Ovarian cell that produces estrogen (a steroid hormone)
c. Muscle cell in the thigh of a long-distance runner
d. White blood cell that engulfs bacteria

Verified step by step guidance

1. Understand the role of the smooth endoplasmic reticulum (smooth ER). The smooth ER is primarily involved in lipid synthesis, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. It is especially abundant in cells that produce steroid hormones, as these hormones are lipid-based.
2. Analyze the function of each cell type provided in the options: - Pancreatic cells secrete digestive enzymes, which are proteins, so they would have more rough ER (involved in protein synthesis) than smooth ER. - Ovarian cells produce estrogen, a steroid hormone, which requires lipid synthesis and thus a high abundance of smooth ER. - Muscle cells store calcium ions in the sarcoplasmic reticulum (a specialized form of smooth ER), but their primary function is contraction, not lipid synthesis. - White blood cells engulf bacteria, a process involving lysosomes and phagocytosis, not smooth ER.
3. Focus on the ovarian cell that produces estrogen. Since estrogen is a steroid hormone, and steroid hormones are synthesized from lipids, this cell type would require a significant amount of smooth ER to carry out its function.
4. Compare the functions of the other cell types to confirm that none of them rely on smooth ER as heavily as the ovarian cell. Pancreatic cells rely on rough ER for protein synthesis, muscle cells use a specialized smooth ER for calcium storage but not lipid synthesis, and white blood cells rely on lysosomes for digestion of engulfed bacteria.
5. Conclude that the ovarian cell producing estrogen is the cell type with the most smooth ER, as its primary function directly involves lipid synthesis, which is the main role of the smooth ER.

Key Concepts

Smooth Endoplasmic Reticulum (Smooth ER)

The smooth endoplasmic reticulum (Smooth ER) is a type of organelle involved in the synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons. Unlike rough ER, it lacks ribosomes on its surface, giving it a smooth appearance. Smooth ER is particularly abundant in cells that produce steroid hormones and lipids, making it crucial for cellular functions related to these processes.

Steroid Hormone Production

Steroid hormones, such as estrogen, are synthesized from cholesterol and are primarily produced in the gonads and adrenal glands. The production of these hormones requires a significant amount of smooth ER, as this organelle is responsible for the enzymatic reactions that convert cholesterol into various steroid hormones. Therefore, cells that produce steroid hormones typically have a well-developed smooth ER.

Cellular Function and Specialization

Different cell types have specialized functions that dictate their organelle composition. For instance, pancreatic cells are rich in rough ER for protein synthesis, while ovarian cells have abundant smooth ER for hormone production. Understanding the relationship between cell type and organelle prevalence is essential for identifying which cell would contain the most smooth ER based on its functional requirements.