LIFESCI 3 Lecture Notes - Lecture 21: Prokaryotic Small Ribosomal Subunit, Consensus Sequence, Ribozyme
Document Summary
I, u (open) reading frame = region between aug start codon & stop codon. 1 reading frame for each protein: 6 different reading frames in dna. Each strand of dna can be organized in codons in 3 different ways -> 3 x 2 =6. Only 1 will code for a protein in a particular gene. Every protein has a different reading frame. Pk cells always have polysomes; ek cells can have polysomes. As soo(cid:374) as (cid:373)rna e(cid:454)its rna pol, e(cid:448)e(cid:374) (cid:271)efo(cid:396)e it"s (cid:272)o(cid:373)pletel(cid:455) t(cid:396)a(cid:374)s(cid:272)(cid:396)i(cid:271)ed, (cid:396)i(cid:271)oso(cid:373)es hop on there; so pk (cid:373)rna does(cid:374)"t (cid:374)eed to (cid:271)e (cid:272)apped. Polysomes can be fractionated by density centrifugation. Only site in ribosome that accommodates trna with more than 1 amino acid: e site = empty trna/trna exit site. Holds trna that already donated amino acid & has held the polypeptide chain, and has passed the chain on to the next trna.
