Which of the following synthesizes lipids and steroid hormones in cells?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2023

Applied Physiology

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2023

Explanation

The Smooth Endoplasmic Reticulum (SER) is a network of tubules responsible for synthesizing lipids, including phospholipids and cholesterol.
It is the primary site for the production of steroid hormones, which are crucial for various physiological processes.
The SER is also involved in detoxification processes, particularly in liver cells (hepatocytes), where it metabolizes drugs and alcohol.
Unlike the Rough ER, the SER lacks ribosomes, which is why its function is centered on lipid and steroid metabolism rather than protein synthesis.

Option B: The Rough Endoplasmic Reticulum (RER) is studded with ribosomes, and its primary function is the synthesis and modification of proteins that are destined for secretion or insertion into membranes.
Option C: Ribosomes are the molecular machines responsible for protein synthesis (translation), where they read mRNA sequences and assemble amino acids into polypeptide chains. They do not synthesize lipids.
Option D: Lysosomes are the cell's 'recycling centers.' They contain powerful digestive (hydrolytic) enzymes to break down waste materials, cellular debris, and foreign invaders. They are involved in catabolism (breakdown), not synthesis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functions of cellular organelles as background academic context rather than a clinical decision trigger.
Understanding organelle function is fundamental to pharmacology. The extensive SER in liver cells (hepatocytes) contains enzymes like the cytochrome P-450 system, which are critical for metabolizing many drugs. SER hyperplasia (increase in size and number) can occur with chronic exposure to certain drugs, affecting drug tolerance and efficacy.
In endocrinology, cells in the adrenal glands and gonads have abundant SER to produce steroid hormones like cortisol, aldosterone, testosterone, and estrogen. Dysfunction of the SER in these cells can lead to endocrine disorders.
What if? If a patient takes a drug like phenobarbital, which is metabolized by the SER, the liver cells would respond by increasing the amount of SER (hyperplasia). This adaptation would lead to faster metabolism of the drug, potentially requiring a higher dose to achieve the same therapeutic effect. It would also increase the metabolism of other drugs processed by the same enzymes.

How to Approach the Question

This is a factual recall question from basic cell biology.
Identify the key functions mentioned in the question stem: 'synthesizes lipids' and 'steroid hormones'.
Systematically review the primary role of each organelle listed in the options.
Rough ER and Ribosomes are primarily associated with protein synthesis. Eliminate these options.
Lysosomes are involved in digestion and waste breakdown. Eliminate this option.
The Smooth ER is known for lipid and steroid synthesis, as well as detoxification. This matches the question's requirements.

Concept Tested & Keywords

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