The site of protein synthesis in the cell is-

Raj. CHO - 2023

Applied Physiology

Easy

Appeared in: Raj. CHO - 2023

Explanation

Ribosomes are the cellular machinery responsible for synthesizing proteins from amino acids.
This process is called translation, where the genetic code carried by messenger RNA (mRNA) is read and used to build a polypeptide chain.
Ribosomes are composed of ribosomal RNA (rRNA) and proteins, and they are found either free in the cytoplasm or bound to the rough endoplasmic reticulum.
The key differentiator is that ribosomes perform the actual assembly of proteins, whereas other organelles like the nucleus and Golgi apparatus are involved in preceding or subsequent steps.

Option A: The Golgi body (or Golgi apparatus) is involved in modifying, sorting, and packaging proteins and lipids after they have been synthesized. It does not create the initial protein chain.
Option B: The cell wall is a rigid outer layer found in plant cells, bacteria, fungi, and algae. Its primary function is to provide structural support and protection. It is not involved in protein synthesis and is not present in animal cells.
Option C: The nucleus contains the cell's genetic blueprint (DNA) and is the site of transcription, where the DNA code is copied into messenger RNA (mRNA). The mRNA then travels out of the nucleus to the ribosomes for protein synthesis.

Visual 1: Diagram: An animal cell with organelles labeled. This visual should highlight the nucleus (where mRNA is made), ribosomes on the rough ER and in the cytoplasm (where protein is made), and the Golgi apparatus (where protein is processed) to illustrate the entire pathway.
Visual 2: Flowchart: The Central Dogma of Molecular Biology. This chart should clearly show the sequence: DNA → Transcription (in Nucleus) → mRNA → Translation (at Ribosome) → Protein.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Function of cellular organelles as background academic context rather than a clinical decision trigger.
The principle of targeting ribosomes is fundamental to the action of many antibiotics. Drugs like tetracyclines, macrolides (e.g., azithromycin), and aminoglycosides selectively inhibit bacterial ribosomes, stopping essential protein synthesis and thus killing the bacteria without harming the patient's own cells.
What if? If a patient has a genetic disorder affecting the function of their mitochondrial ribosomes (mitoribosomes), it would impair the synthesis of proteins essential for cellular respiration, leading to severe metabolic diseases and mitochondrial dysfunction.

How to Approach the Question

This is a factual recall question testing fundamental knowledge of cell biology.
First, identify the key process in the question: 'protein synthesis'.
Next, systematically review the primary function of each organelle listed in the options.
Recall that the Nucleus holds the DNA and is where transcription (DNA to RNA) occurs.
Remember that the Golgi Body is for 'post-processing'—modifying and packaging proteins after they are made.
Recognize that the Cell Wall is for structural support and is not present in all cell types (e.g., animal cells).

Concept Tested & Keywords

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