Translation:

Translation: Protein synthesis occurs in cytoplasm. Requires 3 types of RNA: • Ribosomal RNA (rRNA): associates with proteins to form ribosomes (2 subunits). • mRNA: carries the genetic information. • Transfer RNA (tRNA): deciphers the codons. tRNA 3D conformation of tRNA results from base pairing (H bonds) within the molecule. tRNAs contain non-standard bases due to modification after transcription. 3’ end = amino acid attachment site (acceptor stem). Always CCA. Binds an amino acid via an energy-rich phosphodiester bond. Anticodon = site of complementary base pairing with mRNA. Unique for each species of tRNA. Attaching a residue to a tRNA requires ATP, and specific tRNA synthetase enzymes. Ribosomes have 3 tRNA binding sites: A site, P site, E site. An amino acid brought to ribosome by aminoacyl-tRNA, enters at A site. Peptidyl-tRNA bound to P site – this carries nascent polypeptide chain.