Halloween pets?

Student Assessment of Learning Gains (SALG) website

1. Compare and Contrast DNA Polymerase (like Taq) versus RNA Polymerase. What's the same, what's different?

2. Taq polymerase starts it's work at a primer when you do PCR, how does RNA polymerase figure out where to start it's work during transcription?

3. The coding region of a gene is essentially the exons. The non-coding region of a particular gene is everything else. What gene are you studying in your research project? How many exons does it contain? If a mutation occurs in an intron can that cause your disease? What if a mutation occurred in the TATA box?

Last Night’s Homework

1. Compare and Contrast DNA Polymerase (like Taq) versus RNA Polymerase. What's the same, what's different?

2. Taq polymerase starts it's work at a primer when you do PCR, how does RNA polymerase figure out where to start it's work during transcription?

3. The coding region of a gene is essentially the exons. The non-coding region of a particular gene is everything else. What gene are you studying in your research project? How many exons does it contain? If a mutation occurs in an intron can that cause your disease? What if a mutation occurred in the TATA box?

Last Night’s Homework

The coding region of a gene is essentially the exons. The non-coding region of a particular gene is everything else. If a mutation occurs in an intron can that cause a disease? What if a mutation occurred in the TATA box?

In-class work

DNAmolecule

Gene 1

Gene 2

Gene 3

DNAtemplatestrand

TRANSCRIPTION

TRANSLATION

mRNA

Protein

Codon

Amino acid

Vocabulary?

DNA

Signal

Gene

NUCLEUS

Chromatin modification

Chromatin

Gene availablefor transcription

Exon

Intron

Tail

RNA

Cap

RNA processing

Primary transcript

mRNA in nucleus

Transport to cytoplasm

CYTOPLASM

Transcription

Gene Expression

mRNA in cytoplasm

Translation

CYTOPLASM

Degradationof mRNA

Protein processing

Polypeptide

Active protein

Cellular function

Transport to cellulardestination

Degradationof protein

Transcription

3′

1

2

3

Promoter

TATA box DNA strand5′3′

5′

Transcriptionfactors

5′5′3′3′

RNA polymerase

5′5′ 5′3′

3′

RNA transcript

Transcription initiation complex

INITIATION

Promoter Transcription unit

DNAStart point

RNA polymerase

5′5′3′

3′

Promoter Transcription unit

DNAStart point

RNA polymerase

5′5′3′

3′

Initiation

3′3′

1

RNAtranscript

5′ 5′

UnwoundDNA

Template strandof DNA

Promoter Transcription unit

DNAStart point

RNA polymerase

5′5′3′

3′

Initiation

3′3′

1

RNAtranscript

5′ 5′

UnwoundDNA

Template strandof DNA

2 Elongation

RewoundDNA

5′

5′ 5′ 3′ 3′ 3′

RNAtranscript

Promoter Transcription unit

DNAStart point

RNA polymerase

5′5′3′

3′

Initiation

3′3′

1

RNAtranscript

5′ 5′

UnwoundDNA

Template strandof DNA

2 Elongation

RewoundDNA

5′

5′ 5′ 3′ 3′ 3′

RNAtranscript

3 Termination

5′

5′ 5′ 3′3′

3′Completed RNA transcript

Elongation

RNApolymerase

Nontemplatestrand of DNA

RNA nucleotides

3′ end

Direction oftranscription(“downstream”) Template

strand of DNANewly madeRNA

3′

5′

5′

Protein-coding segment Polyadenylation signal3′

3′ UTR5′ UTR

5′

5′ Cap Start codon Stop codon Poly-A tail

G P PP AAUAAA AAA AAA…

1. Add the Poly-AAAAAA tail and GTP Cap (UTR = untranslated region)

NEXT?: After done making long hnRNA, what next?

hn-RNA

mRNA

Codingsegment

Introns cut out andexons spliced together

5′ Cap

Exon1Intron

5′

1 30 40 100

Exon2Intron

120

Exon3

146

3′Poly-A tail

Poly-A tail5′ Cap

5′ UTR 3′ UTR1 146

2. (Eukaryotes) Remove Introns

Also Alternative Splicing can occur

SPLICING

RNA transcript (hnRNA)

Exon 1 Exon 2Intron

ProteinsnRNA

snRNPs

Otherproteins

5′

RNA transcript (hnRNA)

Exon 1 Exon 2Intron

ProteinsnRNA

snRNPs

Otherproteins

5′

5′

Spliceosome

RNA transcript (hnRNA)

Exon 1 Exon 2Intron

ProteinsnRNA

snRNPs

Otherproteins

5′

5′

Spliceosome

Spliceosomecomponents

Cut-outIntron (lariat)mRNA

Exon 1 Exon 25′

The RNA Tie Club was right!

RNA transcript (pre-mRNA)

Exon 1 Exon 2Intron

ProteinsnRNA

snRNPs

Otherproteins

5′

5′

Spliceosome

snRNA ->

Amino acidattachment site

(a) Two-dimensional structure

Hydrogenbonds

Anticodon

3′

5′

tRNA ->

Ribosome

mRNA

Signalpeptide

Signal-recognitionparticle (SRP)

CYTOSOL Translocationcomplex

SRPreceptorprotein

ER LUMEN

Signalpeptideremoved

ERmembrane

Protein

Insulin!

SRP-RNA rRNA in ribosomes

GFP = Green Florescent Protein (from Jelly fish)

Enhancer TATAbox

PromoterActivators

DNAGene

Distal controlelement

Studying Promoters

GFP

Enhancer TATAbox

PromoterActivators

DNAGene

Distal controlelement

Group ofmediator proteins

DNA-bendingprotein

Generaltranscriptionfactors

Studying Promoters

GFP

Enhancer TATAbox

PromoterActivators

DNAGene

Distal controlelement

Group ofmediator proteins

DNA-bendingprotein

Generaltranscriptionfactors

RNApolymerase II

RNApolymerase II

Transcriptioninitiation complex RNA synthesis

GFP

GFP

Studying Promoters

Controlelements

Enhancer

Availableactivators

Albumin gene

(b) Lens cell

Crystallin geneexpressed

Availableactivators

LENS CELLNUCLEUS

LIVER CELLNUCLEUS

Crystallin gene

Promoter

(a) Liver cell

Crystallin genenot expressed

Albumin geneexpressed

Albumin genenot expressed

GFP (blue)

GFP (red)

blue!

red!

“Brainbow” GFP= Nobel Prize 2008Martin Chalfie, Roger Tsien and Osamu

Shimomura

TRANSCRIPTION

RNA PROCESSING

DNA

RNAtranscript

3′

5′RNApolymerase

Poly-A

Poly-A

RNA transcript(pre-mRNA)

Intron

Exon

NUCLEUS

Aminoacyl-tRNAsynthetase

AMINO ACID ACTIVATIONAminoacid

tRNACYTOPLASM

Poly-A

Growingpolypeptide

3′

Activatedamino acid

mRNA

TRANSLATION

Cap

Ribosomalsubunits

Cap

5′

E

P

A

AAnticodon

Ribosome

Codon

E