Gene Expression

*Protein coding gene

Genes control inherited variation via:

DNA, RNA and protein

*Gene

DNA PhenotypeRNA ProteinReplication Transcription Translation

Phenotype

Proteins and Heredity1902 Archibald Garrod linked biochemistry and inheritance

*Hereditary information controls chemical reactions (in the body)

Genes to Proteins

Transcription

*RNA polymerase

reminder: RNA contains ribose, phosphate group and A, C, G and U (not T)

*RNA polymerase (from E. coli )

a2 b b’s *Sigma factor

Core

*Core

Sigma factor

Holoenzyme

Transcription in Eukaryotes*RNA polymerases:

RNA polymerase I – rRNA (18S, 28S) RNA polymerase II – mRNA RNA polymerase III – small RNA’s ( tRNA, 5S

rRNA, snRNA’s)Eukaryotic promotors:

Goldberg-Hogness box, TATA box, -25 (all)

Hogness box

Hogness box

Hogness box

Hogness box

CAAT box, -80 (many)

CAAT box

CAAT box

CAAT box

Regulatory sequences

Transcriptional Elongation:

RNA Processing in Eukaryotes:

Translation: The Players

Translation: The Players

60S

40S

*Ribosome Structure

70S

Small Subunit

Large Subunit

50S

30S

80S

rRNA:

lsu 2 3

ssu 1 1

Proteins:

lsu 31 49

ssu 21 33

tRNA Structure

tRNA Charging

The Coding Dictionary

5’

3’A U G U U U G C A U A A

Met Phe Ala

Translation Initiation

Translation Elongation

Translation Elongation, con’t

Translation Termination

*Translation– the formation of a protein, directed by an mRNA in association with ribosomes

Review: Translation

Players: ribosomes, mRNA, tRNAs, translation factors

Three stages of translation:Initiation - Recruitment of mRNA to the ribosomeElongation - Synthesis of nacent polypeptideTermination - Release of polypeptide from the ribosome

Prokaryotes

70S 30S and 50S 1

and 2 21 and 34

unprocessed Shine-

Delgarno Some 3 2

2

Components

Monosome Subunits rRNA Proteins mRNA ssu+mRNA Factors Initiation Elongation Termination

Eukaryotes

80S 40S and 60S 1

and 3 33 and 49

processed Kozak

consensus Many ~14 2 2