Which two cell structures work together in the process of protein synthesis
Ribosomes and the endoplasmic reticulum.
The two cell structures that work together in the process of protein synthesis are the ribosomes and the endoplasmic reticulum (ER). Here is a step-by-step explanation of how they collaborate in this process:
Step 1: First, the DNA in the nucleus of the cell contains the genetic instructions for making proteins. These instructions are transcribed into a molecule called messenger RNA (mRNA).
Step 2: The mRNA molecule then exits the nucleus and enters the cytoplasm, where the ribosomes are located.
Step 3: Ribosomes are small structures composed of ribosomal RNA (rRNA) and proteins. They serve as the site of protein synthesis. Ribosomes can be either free-floating in the cytoplasm or attached to the rough endoplasmic reticulum (ER).
Step 4: If a ribosome is free-floating, it binds to the mRNA molecule and initiates protein synthesis. On the other hand, if a ribosome is attached to the rough ER, the mRNA molecule threads through a pore in the ER membrane and into the ER lumen.
Step 5: As the ribosome moves along the mRNA molecule, it reads the genetic code and recruits molecules called transfer RNAs (tRNAs). Each tRNA carries a specific amino acid.
Step 6: The ribosome catalyzes the formation of peptide bonds between adjacent amino acids, following the sequence specified by the mRNA.
Step 7: The growing polypeptide chain is released from the ribosome when a stop codon is reached on the mRNA molecule.
Step 8: If the ribosome is free-floating, the newly synthesized protein is released into the cytoplasm. However, if the ribosome is attached to the rough ER, the protein is threaded into the ER lumen.
Step 9: In the ER lumen, the protein undergoes further processing, such as folding and modification (e.g., addition of sugar groups).
Step 10: Once the protein is properly folded and modified, it is packaged into vesicles and transported to its final destination within the cell or outside of the cell.
In summary, the ribosomes decode the genetic instructions carried by mRNA and catalyze the assembly of amino acids into a polypeptide chain. The endoplasmic reticulum provides the site for protein synthesis, especially for proteins that need to undergo additional processing or transport.