http:// nai_transcription_vo1-lg.mov
TRANSCRIPT
![Page 1: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/1.jpg)
http://www.hhmi.org/biointeractive/media/DNAi_transcription_vo1-lg.mov
![Page 2: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/2.jpg)
From Gene to Protein
Part 2Goal 1- Understand the process of
transcription • How is RNA made?
•How to get from DNA to RNA
Goal 2- Demonstrate how RNA is made • Transcription- Model activity
![Page 3: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/3.jpg)
Try This!Try This!• Molecular Genetics Alphabet
Online Activity
• Crack this code
DNA nucleotide triplet ACG CysCys
![Page 4: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/4.jpg)
Recap: From Gene to Recap: From Gene to Protein Protein Part 1Part 1
What are the two main processes linking gene to protein?
“Cookbook”(genotype)
“Copy of recipe”
“Dish”(phenotype)
![Page 5: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/5.jpg)
The Central Dogma of The Central Dogma of Molecular BiologyMolecular Biology
replication
transcription translation
![Page 6: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/6.jpg)
![Page 7: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/7.jpg)
Why RNA?Why RNA?
![Page 8: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/8.jpg)
Why RNA?Why RNA?
• Not all genes need to be turned on at once. – We can make an RNA transcript of just
ONE GENE– Now we can make the right protein at
the right time in the right location
![Page 9: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/9.jpg)
Why RNA?Why RNA?
In EUKARYOTES…
•DNA cannot leave the nucleus•BUT proteins are built by the ribosomes in the cytosol!•We need a messenger to transfer the genetic code to the ribosomes
![Page 10: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/10.jpg)
mRNAmRNA
• Messenger RNA (mRNA) is a complementary copy of a gene that CAN leave the nucleus
![Page 11: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/11.jpg)
Gaining Access to DNAGaining Access to DNA
![Page 12: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/12.jpg)
4 Phases of 4 Phases of TranscriptionTranscription
1. Initiation2.Elongation3.Termination4.Processing
(Eukaryotes Only)To make a copy you need 3 things:
1.Something to copy – DNA! (cookbook)2.Something to copy with – Nucleotides! (ingredients)3.Something to make the copy – Enzymes! (recipe)
![Page 13: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/13.jpg)
Initiation Initiation (start)(start)
DNA template (the “something” to copy)
Green fluorescent protein
Goal: to express (turn on)
DNA nucleotides
3’ 5’
![Page 14: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/14.jpg)
1. DNA template (the something to copy)
DNA nucleotides
3’ 5’
2. RNA nucleotides (the something to copy with)
3. RNA polymeraseenzyme(the something to make the copy)
![Page 15: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/15.jpg)
3’ 5’
“TA-TA” box
Promoter region Termination sequence
Nucleotides (T-T-A-T-T-T)
Green fluorescent geneTranscription
factorTranscription
factor
Bind/unwind DNA
Transcription unit“Upstream” “Downstream”
![Page 16: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/16.jpg)
InitiationInitiation• RNA polymerase (RNAP) binds to the
double stranded DNA molecule at a promoter sequence (with the help of initiation (transcription) factors)
• It is able to locally unzip DNA with its own built in helicase activity as it constructs an RNA transcript of the DNA
![Page 17: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/17.jpg)
RNA Polymerase II
![Page 18: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/18.jpg)
![Page 19: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/19.jpg)
Enhancers
![Page 20: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/20.jpg)
PromotersPromoters• DNA sequence
upstream of the gene being transcribed
• Determines where RNAP binds and where transcription begins
• Usually rich in Thymine and Adenine (“TATA” box)
![Page 21: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/21.jpg)
![Page 22: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/22.jpg)
ElongationElongation
• One strand of the unzipped DNA acts as a template for RNA synthesis
SG
P SA
P ST
P SC
P SG
P SG
P SA
P SC
P SC
P3´ 5´
SG
PSG
PST
PSC
PSC
PSG
PSA
PST
PSC
P5´ 3´
Template Strand
![Page 23: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/23.jpg)
ElongationElongation
SU
P
SG
PSG
PST
PSC
PSC
PSG
PSA
PST
PSC
P5´ 3´
Template StrandSC
PSG
P SA
P ST
P SC
P SG
P SG
P SA
P SC
P SC
P3´ 5´
SA
PSG
PSC
PSC
PSU
PSG
PSG
P
5´ 3´
Coding Strand
![Page 24: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/24.jpg)
![Page 25: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/25.jpg)
3’
Green fluorescent gene
Transcription factor
Transcription factor
5’
3’5’
Direction of RNA synthesis
5’ 3’
Elongation Elongation (strand)(strand)
![Page 26: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/26.jpg)
ElongationElongation
• mRNA is transcribed in the 5' to 3' direction
• DNA unwinds only in the region of transcription
• After transcription DNA recoils
• Several RNAPs can work on a single gene at once
![Page 27: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/27.jpg)
One more look at Elongation
![Page 28: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/28.jpg)
TerminationTermination• A terminator sequence on the coding
strand tells RNAP when to stop transcribing the mRNA
• RNAP is released and reused and mRNA is released
![Page 29: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/29.jpg)
3’5’
3’5’
Termination (stop)
Transcription unit Termination sequence
messenger RNA (mRNA)
Green fluorescent gene
Translated
Green fluorescent protein
Transcribed (copied)
![Page 30: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/30.jpg)
DNA transcriptionDNA transcription narrated
![Page 31: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/31.jpg)
Transcription VideosTranscription Videos
• mRNA synthesis
• Stages of Transcription
![Page 32: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/32.jpg)
ProcessingProcessing
• In Eukaryotic cells the RNA transcript is called pre-mRNA (or primary RNA) because it must still be modified before it leaves the nucleus
• Why processing?– Remove introns– Protects from degradation in the
cytoplasm
![Page 33: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/33.jpg)
Introns and ExonsIntrons and Exons
Genes contain both coding regions (exons) and non-coding regions (introns)
![Page 34: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/34.jpg)
Introns and ExonsIntrons and Exons
• To produce a final mRNA transcript, introns must be removed
![Page 35: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/35.jpg)
SplicingSplicing
![Page 36: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/36.jpg)
SplicingSplicing
• The Spliceosome is a complex of multiple proteins (snRNPs) and small nuclear RNA (snRNA)
• snRNA binds a specific mRNA sequences at the beginning and end of an intron forming a loop
• The loop is removed and exons are linked
![Page 37: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/37.jpg)
![Page 38: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/38.jpg)
![Page 39: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/39.jpg)
Cap and Tail
S
G
PS
G
PS
U
PS
C
PS
C
PS
G
PS
A
PS
U
PS
C
P
5´ 3´
S
G
PS
G
PS
G
PS
G
P S
A
PS
A
PS
A
PS
A
P S
A
PS
A
PS
A
PS
A
P
cap poly A tail
mRNA transcrip
t
![Page 40: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/40.jpg)
Cap and TailCap and Tail
• To protect RNA from restriction endonucleases in the cytosol, a poly-A tail is added to the 3‘ end of the pre-mRNA
• As an attachment site for the ribosome, a 5‘ cap of modified Gs is added
![Page 41: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/41.jpg)
![Page 42: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/42.jpg)
![Page 43: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/43.jpg)
![Page 44: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/44.jpg)
![Page 45: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/45.jpg)
Try your hand at this:Try your hand at this:
• DNA Sequence:TACGGAGCGTTTCCAACGGTGCATATT
mRNA Sequence:AUGCCUCGCAAAGGUUGCCACGUAU
AA
This code will determine the order of amino acids in a protein…
![Page 46: Http:// NAi_transcription_vo1-lg.mov](https://reader036.vdocuments.us/reader036/viewer/2022062518/56649e845503460f94b8654c/html5/thumbnails/46.jpg)
Try it again, with Try it again, with introns!introns!
• DNA Sequence: INTRONS are red.TACTTGTTATAGTAGTAGGGAGCGCATCTG
AAAAAATCGGCATTTCCACTTCTCGAAACCACCACGGTGCATTCCATT
mRNA Primary Transcript:AUGAACAAUAUCAUCAUCCCUCGCGUAGA
CUUUUUUAGCCGUAAAGGUGAAGAGCUUUGGUGGUGCCACGUAAGGUAA
mRNA Secondary Transcript:AUGAACAAUAUCCGCGUAGACUUUAAAG
GUGAAGAGCUUUGGGUAAGGUAA