2007-2008 AP Biology

Transcriptionfrom

______________________ language

___________________________

language

AP Biology

Transcription Making mRNA

_______________ DNA strand = ____________strand _________________ DNA strand = ________________

same sequence as RNA

synthesis of complementary RNA strand ______________________

enzyme ______________________

template strand

rewinding

mRNA RNA polymerase

unwinding

coding strand

DNAC C

C

C

C

C

C

C

C CC

G

GG

G

G G

G G

G

G

GAA

AA A

A

A

A

A

A A

A

AT

T T

T

T

T

T

T

T T

T

T

U U

5

35

3

3

5build RNA 53

AP Biology

Which gene is read? _______________ region

binding site before beginning of gene ______________ binding site ______________________________________

_____________________________________________

Enhancer region binding site far

upstream of gene turns transcription

on HIGH

AP Biology

Transcription Factors Initiation complex

__________________________________________ suite of proteins which bind to DNA hormones? turn on or off transcription

_________________________________________

AP Biology

Matching bases of DNA & RNA RNA POLYMERASE:

_______________________ bases on one of the DNA strands

U

A G GGGGGT T A C A C T T T T TC C C CA A

U

UU

U

U

G

G

A

A

A C CRNA

polymerase

C

C

C

C

C

G

G

G

G

A

A

A

AA

5' 3'

AP Biology

Eukaryotic genes have junk! Eukaryotic genes are not continuous

__________________________ expressed / coding DNA

_________________________ inbetween sequence

eukaryotic DNA

exon = coding (expressed) sequence

intron = noncoding (inbetween) sequence

intronscome out!

AP Biology

mRNA ______________

eukaryotic DNA

exon = coding (expressed) sequence

intron = noncoding (inbetween) sequence

primary mRNAtranscript

mature mRNAtranscript

pre-mRNA

spliced mRNA

Post-transcriptional processing eukaryotic mRNA needs work after transcription primary transcript = ______________ mRNA ________________

_________________ make ________________________

~10,000 bases

~1,000 bases

AP Biology

Splicing must be accurate No room for mistakes!

a __________________________________________________________

AUG|CGG|UCC|GAU|AAG|GGC|CAU

AUGCGGCTATGGGUCCGAUAAGGGCCAUAUGCGGUCCGAUAAGGGCCAU

AUG|CGG|GUC|CGA|UAA|GGG|CCA|U

AUGCGGCTATGGGUCCGAUAAGGGCCAUAUGCGGGUCCGAUAAGGGCCAU

Met|Arg|Ser|Asp|Lys|Gly|His

Met|Arg|Val|Arg|STOP|

AP Biology

RNA splicing enzymes

snRNPs

exonexon intron

snRNA

5' 3'

spliceosome

exonexcisedintron

5'

5'

3'

3'

3'

lariat

exonmature mRNA

5'

No, not smurfs!“snurps”

____________ small nuclear RNA proteins

______________ several snRNPs ________________

________________ cut & paste gene

AP Biology

Alternative splicing _____________________________________

when is an intron not an intron… different segments treated as exons

Starting to gethard to

define a gene!

AP Biology

A A AA

A3' poly-A tail

mRNA

5'5' cap

3'

G PPP

50-250 A’s

More post-transcriptional processing _________________________ on its trip

from nucleus to cytoplasm enzymes in cytoplasm attack mRNA

_______________________________ add _____________ add ______________

longer tail, mRNA lasts longer: produces more protein

AP Biology

Transcription: In three steps

AP Biology

mRNA

From gene to protein

DNAtranscription

nucleus cytoplasm

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

ribosome

trait

proteintranslation