Protein Synthesis PDF

## Protein Synthesis ### **Part A: 70S Prokaryotic Ribosome** - **Image:** A diagram of a three-dimensional structure showing a 70S prokaryotic ribosome. - **Main components:** - 30S and 50S subunits - mRNA (messenger RNA) running through the ribosome - tRNA (transfer RNA) binding to t...

## Protein Synthesis ### **Part A: 70S Prokaryotic Ribosome** - **Image:** A diagram of a three-dimensional structure showing a 70S prokaryotic ribosome. - **Main components:** - 30S and 50S subunits - mRNA (messenger RNA) running through the ribosome - tRNA (transfer RNA) binding to the mRNA - Growing polypeptide chain - Protein synthesis site - **Focus:** The diagram highlights the different sites where various antibiotics exert their effects on protein synthesis. #### Antibiotics Affecting Protein Synthesis: | Antibiotic | Action | Affected Location | |---|---|---| | **Chloramphenicol** | Binds to the 50S portion of the ribosome and inhibits the formation of peptide bonds. | 50S subunit | | **Erythromycin** | Binds to the 50S portion of the ribosome and prevents translocation, which is the movement of the ribosome along the mRNA. | 50S subunit | | **Streptomycin** | Changes the shape of the 30S portion of the ribosome. This causes the code on the mRNA to be read incorrectly. | 30S subunit | | **Tetracyclines** | Interfere with the attachment of tRNA to the mRNA-ribosome complex | 30S subunit | ### **Part B: Overview of Protein Synthesis** - **Image:** A diagram illustrating the process of protein synthesis. -**Stages:** 1. **Transcription:** - DNA in the Nucleus serve as a template for the synthesis of mRNA. - This newly synthesized mRNA molecule then travels to the cytoplasm through nuclear pores. - The process of transcription produces a pre-mRNA molecule which undergoes further processing into a mature mRNA. 2. **Translation:** - Occurs in the cytoplasm. - Mature mRNA attaches to the ribosome. - tRNA molecules bring specific amino acids to the ribosome, matching them to the codons on the mRNA. - Amino acids are linked together by peptide bonds to form a growing polypeptide chain. - The ribosome moves along the mRNA, reading each codon until a stop codon is reached. - The polypeptide chain is released, folding into a functional protein. -**Key Components:** - **Free amino acids:** Building blocks of proteins - **tRNA:** Carries amino acids to the ribosome and has an anticodon that matches the codon on the mRNA - **Ribosome:** Site of protein synthesis - **Mature mRNA:** Carries the genetic code from the nucleus to the ribosome - **Newly formed protein:** The final product of protein synthesis