Which Organelle Is Responsible for Protein Synthesis? Ribosomes Explained
Which Cell Organelle Is Responsible for Protein Synthesis?
Question: Which cell organelle is responsible for protein synthesis?
Answer
Ribosomes are the main sites of protein synthesis in cells. They read the information carried by messenger RNA (mRNA) and join amino acids together in the correct sequence to form a polypeptide.
What Are Ribosomes?
Ribosomes are small, non-membranous structures made up of ribosomal RNA (rRNA) and proteins. They occur in both prokaryotic and eukaryotic cells.
In eukaryotic cells, ribosomes may occur:
- Free in the cytoplasm
- Attached to the surface of the rough endoplasmic reticulum (RER)
How Do Ribosomes Help in Protein Synthesis?
During translation, a ribosome binds to mRNA and helps decode its nucleotide sequence. Transfer RNA (tRNA) brings specific amino acids to the ribosome, where peptide bonds are formed between them.
The growing chain of amino acids eventually forms a polypeptide, which can fold and become a functional protein.
Free Ribosomes vs RER-Bound Ribosomes
| Ribosomes | Major Role |
|---|---|
| Free ribosomes | Synthesize proteins that generally function within the cell |
| RER-bound ribosomes | Synthesize proteins destined for secretion, membranes, or the endomembrane system |
Ribosomes in Prokaryotes and Eukaryotes
Prokaryotic cells contain 70S ribosomes, whereas eukaryotic cytoplasm contains 80S ribosomes.
The 70S ribosome consists of 50S and 30S subunits, while the 80S ribosome consists of 60S and 40S subunits.
Frequently Asked Questions
Which organelle is responsible for protein synthesis?
Ribosomes are responsible for protein synthesis.
Are ribosomes membrane-bound?
No. Ribosomes are non-membranous structures.
What is the role of rough endoplasmic reticulum in protein synthesis?
The rough endoplasmic reticulum provides a surface to which ribosomes are attached. The ribosomes carry out protein synthesis.
Quick Revision
Ribosome → mRNA decoding → Amino acid linking → Polypeptide → Protein
Conclusion
Ribosomes are the sites of protein synthesis. They translate the information present in mRNA and join amino acids to form polypeptide chains.
