LIFESCI 3 Chapter Notes - Chapter 18.1: Stop Codon, Polysome, Ribozyme
Document Summary
Ribosome: macromolecular machine responsible for protein synthesis. Not encapsulated in a lipid membrane not an organelle, but a macromolecule. Found in the cytosol of all cells, matrix of mitochondria and stroma of chloroplasts. Bacteria/prokaryotes: translate mrna as it is being transcribed. Eukaryotes: mrna is processed and exported before being translated. Brings together mrna codon and charged trna adaptor and catalyzed peptide bond formation. The ribosome is an rna-protein complex composed of two subunits. Bacterial ribosomes: 60% rrna and 40% protein. 50s subunit (larger subunit) contains the peptidyl transferase center. 30s subunit is where aminoacylated trnas base pair with triplet codons in mrna. 50s subunit: 5s, 23s rrna, and 36 r-proteins (l1 - l36) 30s subunit: 16s rrna, and 21 r-proteins (s1-s21) When broken down into components, rna and protein components spontaneously resemble into the two subunits rrnas are highly conserved by evolution, esp in regions with critical functions. Structure and function are similar in all organisms and organelles.
