BIO1140 Lecture 13: Transcription pt.1

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BIO1140 B Dr. Caroline Petit-Turcotte
Transcription (Lecture) 02.27.2017
Learning Objectives:
Understand, describe and demonstrate the steps involved in transcribing DNA to mRNA
Be familiar with the elements comprised in a transcription initiation complex and its role
Explain and demonstrate RNA maturation and splicing
Compare and contrast RNA transcription in prokaryotes vs eukaryotes
Know, describe and/or compare the different elements of control for gene expression in prokaryotes vs eukaryotes
Activators, Repressors (enhancers, silencers), Alternative splicing, Operons
Gees alig oe afte the othe ith itegei egios; a hoosoe has ay diffeet gees ad theye ot
all related to each other
Central Dogma: flo of geeti ifoatio; ells at take ay potei ad deie the gees
DNA can replicate itself; transcription = DNA to RNA (rRNA to ribosomes)
Prokaryotes vs Eukaryotes
DNA is directly transcribed to mRNA in prokaryotes; it can occur anytime
o Only prokaryotes depend on rho protein to terminate RNA transcription
mRNA must be matured in Eukaryotes, it occurs only in G1, G2 of the cell cycle
o eukaryotic genes have different transcription regions:
in Eukaryotes, a transcription unit carries info of only one gene and codes for
either one RNA molecule or one protein; in Prokaryotes, one set of adjacent
genes are often transcribed as a unit, the resulting mRNA molecule carries info
for several proteins
Direction of Transcription RNA strad is produced fro 5’ prooter sites ad eds at
3’ teriator sites
‘NA polyease II eads the  to 5 DNA teplate, tasiig oe of its
strands until it reaches a terminator sequence
o Non-teplate DNA stad is 5 to  – dot at this oe / it ould
podue a  to 5 ‘NA o good
o Complementary base pairing occurs with ribonucleotides (U is
ribonucleotide, T is deoxyribonucleotide)
the sequence encodes a termination signal to stop RNA synthesis or rho
protein initiates termination
o discrete start and stop signals for transcription are encoded in the
DNA template
I eukayotes, ‘NA is odified afte tasiptio, a ap stutue attahes to 5 ed ad a seuee of
adeylates is added to  ed
Starting Transcription in Prokaryotes - Sigma factor is a protein in RNA polymerase that receives signals in DNA to
determine where to start transcription on DNA strand once transcription starts, sigma factor detaches
Starting Transcription in Eukaryotes TBP (TATA box Binding) binds to the TATA sequence on DNA (positions the
helix for transcription), additional protein come and complete the Transcription Initiation Complex (include
transcription factors and regulatory elements), this provides stability and allows RNA polymerase II to start
transcription
Transcription factors AP1 (MAP kinase pathway)
Process of Transcription (Eukaryotes)
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Document Summary

Understand, describe and demonstrate the steps involved in transcribing dna to mrna. Be familiar with the elements comprised in a transcription initiation complex and its role. Compare and contrast rna transcription in prokaryotes vs eukaryotes. Know, describe and/or compare the different elements of control for gene expression in prokaryotes vs eukaryotes. Activators, repressors (enhancers, silencers), alternative splicing, operons. Ge(cid:374)es alig(cid:374) o(cid:374)e afte(cid:396) the othe(cid:396) (cid:449)ith i(cid:374)te(cid:396)ge(cid:374)i(cid:272) (cid:396)egio(cid:374)s; a (cid:272)h(cid:396)o(cid:373)oso(cid:373)e has (cid:373)a(cid:374)y diffe(cid:396)e(cid:374)t ge(cid:374)es a(cid:374)d they(cid:859)(cid:396)e (cid:374)ot all related to each other. Central dogma: flo(cid:449) of ge(cid:374)eti(cid:272) i(cid:374)fo(cid:396)(cid:373)atio(cid:374); (cid:272)ells (cid:272)a(cid:374)(cid:859)t take a(cid:374)y p(cid:396)otei(cid:374) a(cid:374)d de(cid:396)i(cid:448)e the ge(cid:374)es. Dna can replicate itself; transcription = dna to rna (rrna to ribosomes) Dna is directly transcribed to mrna in prokaryotes; it can occur anytime: only prokaryotes depend on rho protein to terminate rna transcription. Direction of transcription rna stra(cid:374)d is produced fro(cid:373) 5" pro(cid:373)oter sites a(cid:374)d e(cid:374)ds at.

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