Key points: summarized from chapter 14

RNA processing

Outline: we will focus on mRNA processing

Overview of the Central Dogma Link DNA to RNA transcription to proteintranslation What is a codon?

Gene organization Introns and exons

What really is a gene?

Steps of pre-mRNA processing Eukaryotes versus prokaryotes

Gene Organization: Is DNA and RNA co-linear?

3 steps of mRNA processing occurs in the nucleus of eukaryotes

5’ CAP

Poly-A tail

Splicing

The 5’Cap

The Poly-A Tail

Cleavage by endonuclease

Basic steps of poly-Adenylation

SplicingSpliceosome

Self splicing

Requires RNA + proteins

Only RNA!

Function as enzymes

Function as enzymes!

Spliceosome Meet the spliceosome

5’ phosphodiester of G

lariat

2’ OH of A

Splicesome: 3 components are required

Note some important aspects of the 5’ and 3’ ends

Where does splicing occurs?

Self-Splicing mRNA’s

Common characteristic of self-splicing mRNA’s

Comments on Alternative processing methods

First: What are the methods of mRNA processing discussed so far?

5’ CAP3’ Poly A TailIntron Splicing

Alternative processing methods

Alternative splicing Multiple 3’cleavage sites RNA editing

BRAINThryoidAnd alternative splicing example

Silencing or interfering RNAs

siRNA miRNA

Onto translation chapter 15