11 Gene Expression: From Transcription to Translation Flashcards
2 general Functions of RNA polymerase
i. Digest incorrect nucleotides (proofreading)
ii. Polymerization (mRNA synthesis)
Function of rRNA
recognize other molecules, provide structural support; catalyze chemical reaction
Function of tRNA
tRNA translate information of mRNA to amino acids
RNA polymerase requires the help of ______ to recognize promoter
transcription factors, or general transcription factors (GTF)
Does RNA polymerase move from 3’ to 5’ or 5’ to 3’ along DNA? What is the direction of RNA transcription?
3’ to 5’; 5’ to 3’
Studying properties of RNA polymerase is hard True or False
True (from lecture 17)
RNA polymermase is said to be processive when….?
remain attached to DNA over long stretch
How many types of RNA polymerase are there in bacteria
1
How many subunits are there in bacteria RNA polymerase
5 subunits form core enzyme
What is sigma factor? in eukaryote or prokaryote?
aids core enzyme to bind to initiation sites for transcription; is loss as RNA chain is elongated
State the 3 RNA Eukaryotic Polymerase and their function
RNA polymerase 2 transcribes mRNA
RNA polymerase 1 transcribes rRNA
RNA polymerase 3 transcribes tRNA
What is GTF? if combined with RNA polymerase 2, what does it form?
GTF = General transcription factors; it forms PIC (preinitiation complex) with RNA polymerase 2
where is TATA box located?
promoter region
Why Thymine is used in DNA but Uracil is used in RNA
- Thymine is more energy expensive
2. Cytosine degrade to uracil; makes it hard to detect mutation of U is used in DNA
A the very beginning of mRNA transcription, what binds to TATA box
TBP - TATA binding Protein
What is TBP a subunit of?
TFIID
As long as __(GTF)___ is attached to DNA, additional RNA polymerase can attach to DNA and transcribe.
(Name the GTF) **IMPORTANT
TFIID
Function of TFIIA, TFIIB, TFIIE, TFIIF
TFIIA =Aids TBP, TFIIB = Bridges the gap E= DNA melting F= recruitment (Lec19)
2 ways TFIIH aid transcription
- Act as Kinase;Catalyse CTD phosphorylation
2. Acts as Helicase; unwinds DNA
Whats CTD
carboxyl terminal domain = 52 repeating 7-amino acid sequence attached to RNA polymerase
Serine in CTD can/cannot be phosphorylated ?
can
when transcribing, RNA polymerase is phosphorylated at where?
CTD
name 2 functions of CTD phosphorylation
- allows transcriptional machinery to separate from GTF
3. provide a docking site for RNA-processing proteins
what does pre-RNA stand for?
primary transcript ; pre-RNA usually attach to protein
Name 3 functions of 5’ methylguanosine cap
- Prevent mRNA degrading due to exonuclease
- assist mRNA transport out of nucleus
- initiate mRNA translation
Name 2 functions of 3’ Poly A tail
- prevent premature mRNA (hnRNA) from degrading
2. Docking site for protein
what is a split gene?
EUKARYOTIC genes containing intervening sequence
Name 2 functions of introns
- Alternate splcing (same DNA template; many protein isoforms)
- exon shuffling
NON-CODING DNA IS Functional!!!!
How does RNA transcription begin in prokaryote?
- RNA polymerase binds to either conserved regions (1.Pribnow box 2.-35 element) in upstream
How does RNA transcription end in prokaryote
- rho factors attachment
2. reach terminator sequence
Steps of RNA transcription initiation
- TFIID’s subunit TBP binds to TATA
- other GTP such as TFIIA, TFIIB binds the TDIID—> forms PIC
- RNA polymerase attach to the PIC
- TFIIH catalyzes phosphorylation
5, transcription is started
