HIS108 Lecture Notes - Lecture 5: Guanosine, Ribonuclease, Polyadenylation
Document Summary
The central dogma: process of dna transcription mrna translation (nucleotide amino acids proteins) Transcription in prokaryotes: dna has a template strand and a non-template strand, sequence of the mrna is the same as that of the non-template strand except for the uracil replaces thymine. Initiation: rna polymerase attaches to specific promoter regions of. Dna: promoter regions (start of the specific gene) indicate the transcriptional starting point where rna synthesis actually begins. 10 region consensus sequence tataat is positioned -10 nucleotides upstream. Note: translation begins even before transcription is complete in prokaryotes. Involves the attachment of a modified guanosine (7-methylguanosine) to the mrna through an u(cid:374)usual 5" to 5" triphosphate li(cid:374)kage. In order to attach the 7-methylguanosine, the terminal 5" phosphate is re(cid:373)o(cid:448)ed fro(cid:373) the (cid:373)rna molecule by a phosphatase enzyme, and another enzyme, guanosyl transferase enzyme, catalyzes the attachment of the 7-(cid:373)ethylgua(cid:374)osi(cid:374)e 5" (cid:272)ap.
