Question 743 of 782

Which of the following cell components is primarily responsible for the synthesis of proteins within the cell?

  • Mitochondria
  • Ribosomes
  • Golgi apparatus
  • Lysosomes

Correct Answer: B

Explanation
The correct option is B. Ribosomes. Detailed Explanation:
  1. Understanding Ribosomes:
  2. Ribosomes are the cellular structures responsible for synthesizing proteins. They can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum (ER), forming what is known as rough ER.
  3. Ribosomes translate messenger RNA (mRNA) into polypeptide chains, which then fold into functional proteins. This process is known as translation.
  4. The Process of Protein Synthesis:
  5. Transcription: The first step in protein synthesis occurs in the nucleus, where DNA is transcribed into mRNA.
  6. Translation: The mRNA then exits the nucleus and enters the cytoplasm, where ribosomes read the mRNA sequence. Each set of three nucleotides (codon) on the mRNA corresponds to a specific amino acid.
  7. Transfer RNA (tRNA) molecules bring the appropriate amino acids to the ribosome, where they are linked together in the order specified by the mRNA, forming a polypeptide chain.
  8. Why Other Options Are Incorrect:
  9. A. Mitochondria:
    • Mitochondria are known as the powerhouse of the cell because they generate ATP through cellular respiration. While they do have their own ribosomes and can synthesize some proteins, their primary function is energy production, not protein synthesis.
  10. C. Golgi apparatus:
    • The Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or delivery to other organelles. It does not synthesize proteins; rather, it processes proteins that have already been synthesized by ribosomes.
  11. D. Lysosomes:
    • Lysosomes are the cell's waste disposal system, containing enzymes that break down waste materials and cellular debris. They do not play a role in protein synthesis.
Summary of Key Points:
  • Ribosomes are the primary site of protein synthesis in the cell.
  • They translate mRNA into proteins by linking amino acids together.
  • Other organelles like mitochondria, Golgi apparatus, and lysosomes have distinct functions unrelated to the synthesis of proteins.
Revision Summary:
  • Ribosomes are essential for protein synthesis, translating mRNA into polypeptides.
  • Mitochondria produce energy, Golgi apparatus modifies proteins, and lysosomes digest waste.
  • Understanding the specific functions of each organelle is crucial for grasping cellular biology.
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