Understanding Protein Synthesis and Cellular Protein Traffic

🧬 Translation is the process of using mRNA to make proteins.

⚙️ The genetic code consists of codons, which are triplets of nucleotides that code for amino acids.

🔡 mRNA contains codons made up of nucleotides, and there are 64 different types of codons.

🧬 The genetic code is consistent and non-overlapping, except for viruses.

🧬 The genetic code is redundant, except for the two exceptions: methionine and tryptophan.

🧬 The wobble effect in tRNA allows for flexibility in amino acid coding, reducing the risk of mutations.

🧬 The process of translation involves the identification of tRNA, charging with amino acids, and the interaction with ribosomes.

✅ Ribosomes play a crucial role in translation, and there are differences between eukaryotic and prokaryotic ribosomes.

📝 The phases of translation include initiation, elongation, and termination, with variations between prokaryotes and eukaryotes.

🧬 The start codon is identified by the Shine Delgarno sequence, which is located upstream from the start codon and contains adenines and guanines.

🧬 Initiation factors and small ribosomal subunits bind the Shine Delgarno sequence and move towards the start codon.

🧬 The initiator tRNA, containing the fmet amino acid, is brought to the start codon by initiation factors.

🧬 Protein synthesis involves initiation, elongation, and termination phases.

📜 In elongation, amino acids are added to the growing polypeptide chain in the A site. The peptidyl transferase enzyme catalyzes the transfer of the amino acid from the P site to the A site.

✨ Translocation then occurs, moving the tRNA from the P site to the E site and the tRNA with the growing polypeptide chain from the A site to the P site.

🧬 The translation process is stopped by a release factor that binds to the stop codon, stops translation, and cuts the peptide in the P site.

🔬 Translation can occur on either free ribosomes or rough endoplasmic reticulum, depending on the destination of the protein.

👥 Proteins synthesized on rough endoplasmic reticulum are either secreted, embedded in the cell membrane, or become part of lysosomes.

🧬 Translation process stops when a stop codon is reached, and the peptide is released into the rough endoplasmic reticulum's lumen.

📚 Proteins synthesized by ribosomes in the rough endoplasmic reticulum are essential for secretion, membrane incorporation, and lysosomal functions.

🧪 Proteins synthesized by free ribosomes are important for cytosolic, nuclear, mitochondrial, and peroxisomal functions.

🔬 Proteins undergo various modifications, including glycosylation, lipidation, phosphorylation, hydroxylation, methylation, acetylation, and trimming.