Lecture 15 From Gene to Protein

ribose deoxyribose H

Transcription: Translation The synthesis of RNA using DNA as the template Occurs in the nucleus Translation The synthesis of protein using mRNA as the template Occurs in the cytoplasm Requires ribosomes (free or attached to the rough ER)

Basic organization of a gene….. Sequence-specific TFs TATA promoter transcription unit

Transcription

Transcription - Initiation Transcriptional Initiation: promoter of a gene TATA box-binding factor (TBP) and other general transcription factors RNA polymerase Sequence-specific transcription factors Sequence-specific transcription factors promote formation of the PIC

Elongation ribonucleotides are added to the growing chain by RNA polymerase II uses DNA sequence as template 5’ to 3’ synthesis (anti-parallel to DNA) opens up 10-20 base pairs at a time new RNA strand peels away from the DNA template as it is synthesized

Termination termination: when polyadenylation signal is reached (AAUAAA) 1-35 nucleotides downstream – pre-mRNA is cut free from the RNA polymerase RNA Polymerase continues on for hundreds of nucleotides….

Modification and Processing 5’ methylated cap 3’ poly A tail splicing Enzyme for 5’ cap: attached to RNA pol II

PAP – poly A polymerase

Introns – regulatory function -alternative splicing

Translation - tRNA

Translation – the mRNA code

Translation: Initiation, Elongation and Termination

2. Elongation

3. Termination