Chapter 17 From gene to protein
One gene/One polypeptide
Define transcription and translation Compare Prokaryotic and Eukaryotic cells video
(21 different AA’s) mRNA code Ave. protein is 400AA long
DNA= triplets RNA= codons 5’ to 3’ Pre-mRNA (primary transcript)
Promoter: TATA Box Transcription factors RNA poly- merase Transcription initiation complex Movie
Finishing the pre-mRNA Introns: (intruding) spliced out Exons: kept, will be Expressed in the cell
video snRNP’s identify introns Introns are cut out at a Spliceosome Final mRNA has only genes that will be tran-scribed in cell no “junk genes” video
Translation Read 5’ to 3’ The production of polypeptides on a Ribosome tRNA, transfer RNA carries in the amino acids to the ribosome (transfers the A.A) Read 5’ to 3’
A P E: Video Movie Aminoacyl-tRNA synthetase Peptidyl tRNA binding site Exit Video Movie
Termination of the translation
Translation of many polypeptide chains at once
The signal mechanism: signal peptides Free or bound ribosomes?
Coupled transcription and translation
Mutations: Look at the result of just one base difference out of 574 Amino acids (1722 bases)
The wrong protein Nothing formed
Repairing mistakes
Summary